Best Practices for Specific Chemicals
Aqua Regia is a fresh mixture of hydrochloric and nitric acids used to etch metals and clean glassware. It is very corrosive to skin and respiratory tract.
It needs to be mixed fresh for each use and evolves gasses which have caused many accidents and container ruptures. It should be used only when absolutely necessary. For detailed use instructions, you must develop your own standard operating procedure for your process by reviewing the Aqua Regia Chemical Factsheet.
Asbestos is a naturally occurring mineral fiber extensively used in building materials from the 1930s until the 1970s. It is resistant to heat, mechanical stress, and water. Asbestos fibers are only a hazard when they become airborne and can be inhaled.
Learn more about the Asbestos Program
Beryllium metal and its alloys are used in a wide variety of industrial products because they are light and resistant to heat, stress, and strain. Beryllium is highly toxic to the lungs and is a confirmed human carcinogen. All procedures that may be an exposure hazard should be evaluated by the EHS Office to insure that air concentrations are within acceptable levels. The ACGIH TLV for beryllium is 0.05 ug/m3. The OSHA PEL is 0.2 ug/m3.
All employees with potential for exposure can enroll in the annual medical surveillance program sponsored by the MIT Medical Department.
For additional information about safe work practices (including use of a respirator, gloves, clothing, etc), consult the MIT Beryllium Program and Procedures.
The inhalation of dust, fumes, or mists containing beryllium or beryllium compounds present a very serious health hazard. Laboratory processes that can produce fumes or inhalable dust include heating, grinding, and machining of beryllium and its alloys.
In humans, beryllium causes both acute and chronic lung disease and lung cancer. Acute beryllium disease has been seen after brief exposures to soluble beryllium compounds. Symptoms range from a mild inflammation of nasal passages to bronchitis and lung inflammation.
Chronic beryllium disease is characterized by lung fibrosis (scarring) and inflammation, causing breathlessness upon exertion, weakness, chest pain, enlarged heart, and ultimately death. Beryllium has been documented to cause lung cancer in industrial beryllium production facilities. Beryllium can also cause allergic skin reactions.
To work safely with beryllium, all labs and shops must do the following:
- All procedures that potentially generate beryllium particulates, such as heating or machining or aerosols of beryllium salts, must be evaluated by the EHS Office to insure that air levels are safe.
- All researchers working with beryllium in a manner that creates airborne exposure can enroll in the Beryllium Surveillance Program at MIT Medical by calling (617) 452-3477. The program is voluntary and free.
- Standard operating procedures for specific operations should be established before working with beryllium and its compounds. These will normally include the use of fume hoods or local exhaust ventilation.
- Prior to working with beryllium, employees must receive training from their supervisor. Beryllium users must also complete either Chemical Hygiene or Hazard Communication training and Managing Hazardous Waste training.
The following resources and detailed information is referred to in the Cryogen Safety web course (certificate required).
Best practice for dispensing liquid from a low pressure container to a dewar:
- Don a face shield and safety glasses, cryogenic gloves, long pants without cuffs, closed-toed shoes, and a laboratory coat.
- Next connect a transfer line to the liquid valve, if one is not already present, making sure the fittings match. Please note that the valve will be labeled. The transfer line should have a phase separator attached to reduce turbulence and the release of gas while filling.
- Check the pressure in the cylinder. It should read approximately 22 pounds per square inch. Position the Dewar on the floor at the base of the cylinder, or on some other support below waist level and insert the transfer line into the Dewar. The end of the transfer line should extend to the bottom, or just off the bottom, of the Dewar. Keep bystanders at least four feet away while filling in case of splashing.
- Open the liquid valve one half to three quarters of a turn to begin cooling down the transfer hose and adding the cryogen to the Dewar. The warm hose and Dewar will vaporize the cryogen as it cools and this could create splashing particularly if it is added too quickly. The pressure in the container will drive the liquid out through the valve.
- Once the hose and Dewar have cooled, open the liquid valve to obtain the desired rate of flow. However, if you fully open the valve, be sure to close it a quarter turn. A fully opened valve may freeze in that position causing a spill. A good flow rate is typically evident by a moderate vapor trail coming from the mouth of the Dewar. Listen for the change in sound as the Dewar fills – a higher pitch indicates the Dewar is getting full.
- When full, close the liquid valve. Remove the transfer line but be careful not to drop it or allow the phase separator to hit a solid object which will cause it to break. Watch out for any cryogen that continues to spill out of the transfer hose. Finally, place the top on the Dewar, pushing it all the way on and then pulling it up so that it is loose.
Best practice for dispensing gas from a high pressure container to equipment or system:
- Don cryogenic gloves, safety glasses, long pants without cuffs, closed-toed shoes, and a laboratory coat.
- Check the pressure in the cylinder. It should be approximately 230 pounds per square inch, but this will vary with the gas dispensed.
- Next connect the inlet of a suitable regulator to the gas use valve or a transfer line from this valve to an appropriate wall mounted regulator. Please note that the gas withdrawal valve will be labeled. The regulator should be designed for use with cryogens and adjustable over the desired pressure range.
- The outlet of the regulator is connected to the system receiving the gas using the appropriate transfer line – in this case it’s a dedicated gas line.
- Next close the regulator valve and open the gas use valve. Adjust the gas regulator to deliver the gas at the desired pressure, for example, 90 pounds per square inch. At this point you may begin withdrawing gas.
- In applications where large volumes of gas will be withdrawn from the container, the pressure building valve will be opened. This valve operates an internal circuit that allows more liquid to vaporize then would naturally occur through evaporation alone. The vendor supplying the container generally knows your application and opens or closes this valve when delivered.
The transportation of cryogenic containers in elevators represents a potential asphyxiation risk if researchers become trapped in an elevator with a container of cryogen. If a passenger elevator must be used, the first person rolls the container into the elevator, posts a clearly visible sign that warns staff and students not to enter the elevator. The first person pushes the elevator button for the appropriate floor and immediately gets off the elevator. The second person meets the elevator, removes the container and the sign.
This table lists the change in volume as the gas transitions from liquid to gas at room temperature. The resulting pressure that would be generated inside a container from trapped liquid under these conditions is also listed.
Helium | Nitrogen | Oxygen | CO2 | |
---|---|---|---|---|
Boiling point °F (1 @atm) | -452 | -321 | -297 | -108 |
Change in volume as liquid expands to gas at room temperature (liquid-to-gas expansion ratio) | 780 | 710 | 875 | 790 |
Pressure generated from trapped liquid allowed to warm to room temperature | 10,950 psig | 10,230 psig | Not Specified | Not Specified |
Note 1: Although CO2, which has a slightly higher boiling is technically not cryogenic liquid but has similar properties and is often included in this category. (Note: Source Argonne National Laboratory)
Resources / Additional Information
- LN2 Ice Cream Safety Plan Template
- Cryogenic Liquids SOP (certificate required)
- Cryogen Valve Diagrams
- Cryogen Safety Web Course Narrative
- Safetygram – Helium
- Safetygram – Oxygen
Cyanide salts (sodium and potassium) have a white crystalline or powder appearance. They are highly toxic by inhalation, ingestion, and can even be absorbed through the skin. As little as 50 mg can be fatal to a human being. Mixing dry salts with atmospheric moisture or with acids can release poisonous hydrogen cyanide gas which can be fatal.
MIT Procurement will not allow you to purchase cyanide salts unless the EHS Office approves your order. You must review and follow all the Cyanide Salts Safety Guidelines.
Formaldehyde is classified by OSHA as a Particularly Hazardous Substance, a probable carcinogen, and a respiratory and skin sensitizer. It has a strong odor detectable at 0.04 to 1 parts per million (ppm). The OSHA 8 hour Permissible Exposure Limit is 0.75 ppm. The 15 minute Short Term Exposure Limit is 2 ppm.
Formaldehyde can be used safely provided that the following precautions are followed:
- Use in a fume hood or other ventilated enclosure such as a dissection hood or ventilated downdraft table unless very dilute or small quantities.
- Wear gloves with good resistance to formaldehyde, such as the disposable nitrile Best NDex glove – Latex gloves provide short term splash resistance only and should generally not be worn for formaldehyde work.
- All formaldehyde waste should be collected and disposed of as hazardous waste.
- The Chemical Hygiene Lab Specific Training for your lab should cover formaldehyde hazards and safe use practices.
- Call the EHS Office (617-452-3477) if you can smell formaldehyde during your procedures.
- Make an appointment with the MIT Medical Department (617-253-4481) if you experience any symptoms of eye, nose, or throat irritation during your work with formaldehyde.
MIT must identify all laboratory activities that are above the OSHA action level or short term exposure level (STEL) through initial air monitoring and provide training, medical surveillance, and engineering and work practice controls if air levels warrant it. The Industrial Hygiene Program (IHP) in the EHS Office has performed extensive air sampling for formaldehyde during a variety of lab activities such as animal perfusion, dissections, and tissue fixation and found the results to be below OSHA levels provided that suitable exhaust ventilation is used.
With proper exhaust ventilation, you should not detect any odors from formaldehyde work nor experience any symptoms of exposure such as eye tearing or throat irritation. If you do, please contact EHS immediately at (617) 452-3477 for an evaluation.
EHS sends a questionnaire annually to laboratory EHS Representatives to survey formaldehyde use and conducts air sampling of procedures where there may be a potential for exposure. Notify EHS for an evaluation if your procedures change and you work with large quantities of formaldehyde, perform animal perfusions, or do extensive tissue dissection work.
Hydrofluoric acid (HF) is a particularly hazardous substance, like many acids, but has added dangers that make it especially dangerous. It is less dissociated than most acids and deeply penetrates the skin. Symptoms of exposure may be delayed for up to 24 hours, even with dilute solutions. HF burns affect deep tissue layers, are extremely painful and disfiguring. The highly reactive fluoride ion circulates throughout the body and can cause multiple organ toxicity, including heart arrhythmias and death, if not treated.
Any suspected skin exposures to HF should be immediately flooded with water, decontaminated with calcium gluconate gel, and be treated at MIT Medical”.
“In case of:
- Large area of skin exposure (greater than the palm of the hand) and the HF concentration is greater than 5%
- Eye exposure
- Inhalation exposure
- Ingestion
Immediately call 100 or 617-253-1212, ask for Advanced Life Support (ALS) Ambulance, follow appropriate irrigation protocol and go directly to the hospital.
All laboratories using HF must have unexpired calcium gluconate decontamination gel on hand. You may obtain it from the EHS Office by completing this form.
Calcium Gluconate Gel Request Form
All employees are required to be trained by the EHS Office before beginning work with HF. The training covers safe use, personal protective equipment, and decontamination procedures. The training can be taken on the web or in the classroom. Visit Atlas and select Learning Center to search and register for the training.
Isoflurane is an anesthetic gas that is widely used at MIT. Isoflurane is a halogenated anesthetic gas and one of the most commonly used inhalation anesthetics in experimental and veterinary animal procedures.
There are many different set-ups in laboratories that potentially will expose researchers and employees to isoflurane. Acute exposure with isoflurane includes headaches, dizziness, fatigue, temporary blurring of vision, and nausea. Chronic health effects include a slight increase in risk for miscarriages, liver and kidney disease, and possible reproductive effects. Currently, there is no established exposure limit specific to exposure to isoflurane. The MIT EHS Office is using 2 ppm as an 8-hour time-weighted average (TWA). For additional information about isoflurane safe work practices, please read the Standard Operating Guideline, Isoflurane Safety Guidelines (certificate required).
This document can also be located on the Forms & SOP’s page; search for “Isoflurane Safety Guidelines”.
Lead can be found in many places on campus including paint, solder, ceramic products, and water. Lead and its compounds are toxic and present a health hazard when ingested or inhaled. Once absorbed it is carried throughout the body by the bloodstream to other organs.
Excessive lead levels can result in damage to the brain, kidney, CNS, blood, and reproductive systems. Lead is extremely hazardous to children because it is easily absorbed into their bodies and interferes with the developing brain, central nervous systems, and other organs. Lead is excreted mainly through the urinary and GI tract. Not all the lead is excreted though; some is absorbed in the bones.
MIT is committed to providing students and employees with safe work environments free from any health hazards and we comply with pertinent Federal and State guidelines and regulations. Such regulations require the identification of lead-containing materials, maintaining painted surfaces, effective and proper abatement when necessary, and proper disposal of waste generated by the abatement project.
Lithium and sodium compounds include (but are not limited to): butyllithium, lithium aluminum hydride, lithium borohydride, lithium hydride, lithium nitride, sodium aluminum hydride, sodium borohydride, sodium hydride.
The EHS Office strongly recommends the use of a process safety procedure that identifies the appropriate personal protective equipment (PPE), engineering controls, waste management requirements, and emergency response steps to ensure those working with these reactive materials are aware of the hazards.
If your lab plans to, or currently uses, reactive lithium and / or sodium compounds it is recommended that you ensure the appropriate extinguishing agent (such as a Class D extinguisher, sand or a Met-L-X or Lith-X suppression material) are available.
For specific information, refer to Fire Safety. Please note that the list of compounds below is not inclusive. Refer to the Safety Data Sheet (SDS) and/or contact the EHS Office for assistance.
Upon completion of your experiment using lithium or sodium metals or powders, specifically, follow these guidelines or contact the EHS Office for assistance in preparing the waste or surplus materials for hazardous waste pick-up:
- Within the glove box or controlled environment, containerize your waste materials and submerge them in oil.
- Remove the container of waste from the glove box, label it with a red tag, spell out the constituents, indicate Ignitable/Reactive as the associated hazards, date the container, and place it in your lab’s SAA.
- Upon dating, place a waste collection pickup request online for removal from the lab within 3-days.
Mercury is a naturally occurring element that is found in air, water, and soil. It exists in several forms: elemental or metallic mercury, inorganic mercury compounds, and organic mercury compounds.
- When elemental mercury is spilled or a device containing mercury breaks, the exposed mercury volatilizes at room temperature and becomes an odorless toxic vapor. Mercury vapors will increase in warm or poorly-ventilated rooms or spaces.
- Mercury and its compounds penetrate the intact skin. Wear nitrile, PVC, or natural rubber gloves for elemental mercury. For organo-alkyl compounds, use Silver Shield or 4H gloves and an outer glove of heavy-duty nitrile or neoprene.
- The nervous system is very sensitive to all forms of mercury. Methylmercury and metallic mercury vapors are more harmful than other forms because more mercury in these forms reaches the brain.
- Exposure to high levels of metallic, inorganic, or organic mercury can permanently damage the brain, kidneys, and developing fetus.
Nanomaterials are defined by the American Society for Testing and Materials as a material with two or three dimensions between 1 to 100 nm. They can be composed of many different base materials such as carbon or silicon, and metals such as gold, cadmium, and selenium. They can also have different shapes: such as nanotubes, nanowires, or crystalline structures such as quantum dots and fullerenes.
Nanomaterials often exhibit very different properties from their respective bulk materials: greater strength, conductivity, and fluorescence, among other properties.
Nanoparticles are generally similar in size to proteins in the body and are considerably smaller than many cells in the body. Human alveolar macrophages are 24 um in diameter and red blood cells are 7-8 um in diameter. Cells growing in tissue culture will pick up most nanoparticles.
Particles in the nanometer size range do occur both in nature and as an incidental byproduct of existing industrial processes. Nanosized particles are part of the range of atmospheric particles generated by natural events such as volcanic eruptions and forest fires. They also form part of the fumes generated during welding, metal smelting, automobile exhaust, and other industrial processes. One concern about small particles that are less than 10 um is that they are respirable and reach the alveolar spaces of the lungs.
The ability to be taken up by cells is being used to develop nanosized drug delivery systems and does not inherently indicate toxicity.
Quantum Dots
Quantum dots are nanocrystals containing 1,000 to 100,000 atoms and exhibiting unusual “quantum effects” such as prolonged fluorescence. They are being investigated for use in immunostaining as alternatives to fluorescent dyes. The most commonly used material for the core crystal is cadmium-selenium, which exhibits bright fluorescence and high photostability. Both bulk cadmium and selenium are toxic to cells. One of the primary sites of cadmium toxicity in vivo is the liver.
Carbon Nanotubes
Carbon Nanotubes (CNT) can have either single or multiple layers of carbon atoms arranged in a cylinder. The dimensions of typical single-wall carbon nanotubes (SWCNT) are about 1-2 nm in diameter by 0.1 um in length. Multiple wall carbon nanotubes (MWCNT) are 20 nm in diameter and 1 mm long.
CNT may behave like fibers in the lung. They have properties very different from bulk carbon or graphite. They have great tensile strength and are potentially the strongest, smallest fibers known. CNT have been tested in short term animal tests of pulmonary toxicity and the results suggest the potential for lung toxicity though there are questions about the nature of the toxicity observed and the doses used.
Fullerenes
Fullerenes are another category of carbon-based nanoparticles. The most common type has a molecular structure of C60 which takes the shape of a ball-shaped cage of carbon particles arranged in pentagons and hexagons. Fullerenes have many potential medical applications as well as applications in industrial coatings and fuel cells, so a number of preliminary toxicology studies have been done with them.
The toxicity of most nanomaterials is currently unknown. Studies suggest that the levels of toxicity depend on the base material of the nanoparticle, its size and structure, and its substituents and coatings.
The preliminary conclusions to be drawn from the toxicology studies to date is that some types of nanomaterials can be toxic, if they are not bound up in a substrate and they are available to the body. Multiple government organizations are working to fund and assemble toxicology information on these materials. In the interim, MIT researchers must use procedures that prevent inhalation and dermal exposures because at this time nanotoxicology information is limited.
Handling Nanoparticles
Nanomaterials of uncertain toxicity can be handled using the same precautions currently used at MIT to handle toxic materials: use of exhaust ventilation (such as fume hoods and vented enclosures) to prevent inhalation exposure during procedures that may release aerosols or fibers and use of gloves to prevent dermal exposure. The EHS Office will continue to review health and safety information about nanomaterials as it becomes available and distribute it to the MIT community.
Changes in Technology
The current nanotechnology revolution differs from past industrial processes because nanomaterials are being engineered and fabricated from the “bottom-up”, rather than occurring as a byproduct of other activities. The nanomaterials being engineered have different and unexpected properties compared to those of the parent compounds. Since their properties are different when they are small, it is expected that they will have different effects on the body and will need to be evaluated separately from the parent compounds for toxicity.
Currently, nanomaterials have a limited commercial market. Some nanomaterials are used as catalyst supports in catalytic converters; nanosized titanium dioxide particles are used as a component of sunscreens; carbon nanotubes have been used to strengthen tennis rackets; components in silicon chips are reaching the 45 to 65 nm range.
Research and industrial labs are working at the intersection of engineering and biology to extend uses to medicine as well as all areas of engineering. The impact is expected to revolutionize these areas. Government agencies in the US and Europe are beginning to fund toxicology research to understand the hazards of these materials before they become widely available.
Translocation in the Body
Once in the body, some types of nanoparticles may have the ability to translocate and be distributed to other organs, including the central nervous system. Silver, albumin, and carbon nanoparticles all showed systemic availability after inhalation exposure.
Significant amounts of 13C labeled carbon particles (22-30 nm in diameter) were found in the livers of rats after 6 hours of inhalation exposure to 80 or 180 ug/m3 (Oberdorster et al. 2002). In contrast, only very small amounts of 192Ir particles (15 nm) were found systemically. Oberdorster et al. (2004) also found that inhaled 13 C labeled carbon particles reached the olfactory bulb and also the cerebrum and cerebellum, suggesting that translocation to the brain occurred through the nasal mucosa along the olfactory nerve to the brain.
The ability of nanomaterials to move about the body may depend on their chemical reactivity, surface characteristics, and ability to bind to body proteins.
Titanium Dioxide Nanoparticles
Nanoscale titanium dioxide has shown very different properties from the micron-scale material in tests of lung toxicity. In addition, 14 to 40 nm titanium dioxide produced lung cancer in rats at doses of 10 mg/m3; micron-sized dust produced cancer only at very high doses (250 mg/m3). Based on these results the National Institute of Occupational Safety and Health (NIOSH) issued a recommended safe occupational exposure limit of 0.1 mg/m3 for nanoscale material and 1.5 mg/m3 for micron size material.
The International Agency for Research on Cancer (IARC) has also determined that titanium dioxide is a category 2B carcinogen: possibly carcinogenic to humans. Last year Wang et al (2008) showed that nanoscale titanium dioxide when inhaled could travel to the brain by way of olfactory neurons. Once in the brain, it caused oxidative stress and neuronal degeneration in several areas, including the hippocampus which is involved with short-term memory.
Nanoscale titanium dioxide joins several other types of nanomaterials (manganese oxide, nanocarbon, and some viruses) that can enter the brain directly by means of the olfactory pathway from the nose.
Skin Penetration
There is currently no consensus about the ability of nanoparticles to penetrate through the skin. Particles in the micrometer range are generally thought to be unable to penetrate through the skin. The outer skin consists of a 10 um thick, tough layer of dead keratinized cells (stratum corneum) that is difficult to pass for particles, ionic compounds, and water soluble compounds. Tinkle et al. (2003) found that 0.5 and 1 um dextran spheres penetrated “flexed” human skin in an in vitro experiment.
Particles penetrated into the epidermis and a few entered the dermis only during flexing of the skin. Particles 2 and 4 um in diameter did not penetrate. Rymen-Rasmussen et al. (2006) also found that quantum dots penetrated through pig skin and into living dermis using an in vitro pig skin bioassay which is considered a good model for human skin.
Micronized titanium dioxide (40 nm) is currently being used in sunscreens and cosmetics as sun protection. The nm particles are transparent and do not give the cosmetics the white, chalky appearance that coarser preparations did. The nm particles have been found to penetrate into the stratum corneum and more deeply into hair follicles and sweat glands than um particles though they did not reach the epidermis layer and dermis layers (Laddeman et al., 1999).
There is also a concern that nm titanium dioxide particles have higher photo-reactivity than coarser particles and may generate free radicals that can cause cell damage. Some manufacturers have addressed this issue by coating the particles to prevent free radical formation. The FDA has reviewed available information and determined that nm titanium dioxide particles are not a new ingredient but a specific grade of the original product (Luther, 2004).
The MIT EHS Office considers nanoparticles that have the potential for release into the air to be handled as particularly hazardous substance because their toxicity is, for the most part, unknown and early studies have been suggestive of toxic effects. In the future, many types of nanoparticles may turn out to be of limited toxicity but precaution must be used until we know more. The following best practices should be followed:
- Work with nanoparticles that may release particles should be conducted in enclosures, fume hood, glove boxes, and other vented enclosures.
- All work should be done with gloves (at a minimum disposable nitrile gloves)
- Currently, nanoparticles and solutions containing them are being disposed of as hazardous waste. Label all containers of nanomaterials (including waste) with the designation “nano”.
- Before work, review the Best Practices for Handling Nanomaterials in Laboratories
- Review the checklist for developing your laboratory Standard Operating Procedure for nanomaterials work
- Call the EHS Office at 617-253-0344 for exposure evaluation of experimental setups and additional information.
EHS has developed a training, Nanomaterials Health and Safety Course, which includes information on the toxicity of different types of nanomaterials and laboratory practices to prevent exposures.
If you have any questions after reviewing these materials, contact the EHS Office at environment@mit.edu or 452-3477. An EHS Officer can also visit your lab for a review of your procedures.
Nanomaterials can be handled in fume hoods, biosafety cabinets, and other exhausted enclosures. However, these hoods often have high air velocities that can be disruptive to handling dry, lightweight nanomaterials.
Laboratories in Mechanical Engineering and Center for Materials Science and Engineering have purchased a specially designed type of enclosure for handling nanopowders. This type of enclosure differs from a traditional fume hood in that the slots for exhausted air are located above the floor of the unit. Therefore air currents do not disturb the handling of light, fluffy nanopowders or nanotubes. These units were originally developed to enclose sensitive balances but can be used either to weigh nanomaterials or manipulate samples.
Contact EHS for vendors who supply these enclosures.
As nanotechnology emerges and evolves, potential environmental applications and human health and environmental implications are under consideration by the EPA and local regulators.
EPA has a number of different offices coordinating its review of this rapidly evolving technology. The EPA is currently trying a voluntary approach to testing and developing a stewardship program. There are currently no guidelines from the EPA specifically addressing the disposal of waste nanomaterials. It seems that regulation at some level is inevitable. Some political subdivisions, including the City of Cambridge, are already evaluating local regulation.
MIT is taking a cautious approach to nano waste management. It is our belief that regulation is inevitable. In order to better understand the potential volumes and characteristics of these waste streams, we are advising that all waste materials potentially contaminated with nanomaterials be identified and evaluated or collected for special waste disposal.
The following waste management guidance applies to nanomaterial-bearing waste streams consisting of:
- Pure nanomaterials (e.g., carbon nanotubes)
- Items contaminated with nanomaterials (e.g., wipes/PPE)
- Liquid suspensions containing nanomaterials
- Solid matrixes with nanomaterials that are friable or have a nanostructure loosely attached to the surface such that they can reasonably be expected to break free or leach out when in contact with air or water, or when subjected to reasonably foreseeable mechanical forces.
The guidance does not apply to nanomaterials embedded in a solid matrix that cannot reasonably be expected to break free or leach out when they contact air or water, but would apply to dusts and fines generated when cutting or milling such materials.
DO NOT put material from nanomaterial – bearing waste streams into the regular trash or down the drain. Before disposal of any waste contaminated with nanomaterial, call the EHS Office (45(617) 452-3477) for a waste determination.
Collect paper, wipes, PPE, and other items with loose contamination in a plastic bag or other sealing container stored in the laboratory hood. When the bag is full, close it, take it out of the hood and place it into a second plastic bag or other sealing container. Label the outer bag with the laboratory’s proper waste label. On the Contents section, note that it contains nano-sized particles and indicate what they are.
Currently, the disposal requirements for the base materials should be considered first when characterizing these materials. If the base material is toxic, such as silver or cadmium, or the carrier is a hazardous waste, such as a flammable solvent or acid, clearly they should carry those identifiers. Many nanoparticles may also be otherwise joined with toxic metals of chemicals. Bulk carbon is considered a flammable solid, so even carbon-based nanomaterials should be collected for determination as hazardous waste characteristics.
The EHS Office regularly seeks out new information regarding nanomaterials and will alert the MIT community about additional toxicology studies as they become available. We also request that MIT researchers alert us about studies that they learn so we can distribute them to the MIT community.
We would like to observe handling procedures in different labs so we can share good practice information within the MIT community. Many of the articles listed below can be accessed electronically through the MIT Libraries if an electronic subscription is available. Web sites are also provided where available.
Additional MIT Guidance
- Best Practices for Handling Nanomaterials in Laboratories
- Checklist for Nanomaterials Standard Operating Procedures
Web Sites
- Gradient Corp. Monthly EH&S Nano News
- National Institute for Occupational Safety and Health (NIOSH)
- National Nanotechnology Infrastructure Network (NNIN)
- National Center for Biotechnology Information (NCBI) Pub Med – Search for articles on nanoparticle toxicity
- Safe Nano (UK) – Regularly updated wensite on health and safety risks of nanotechnology with comments by toxicologists and regulators
- Borm P JA, Robbins D, Haubold S et al. The potential risks of nanomaterials: a review carried out for ECETOC. Part Fiber Toxicol 3:11-35 2006.
- Colvin VL. The potential environmental impact of engineered nanmoaterials. Nature Biotechnology 21:1166-1170 2003. [Note: Excellent and succinct overview of nanotoxicology.
- Oberdorster G, Oberdorster E, Oberdorster J. Nanotoxicology: An Emrging Discipline Evolving from Studies of Ultrafine Particles. Environmental Health Perspectives 113:823-839 2005.
- Health and Safety Executive (UK). Health effects of particles produced for nanotechnologies. Document EH75/6. 35 pp. December 2004. Available at: www.hse.gov.uk. [Search for EH75/6]
- Health and Safety Executive (UK). Nanoparticles: an occupational hygiene review. Research Report 274. 100 pp. 2004. Available at: www.hse.gov.uk. [Search for RR274]
- BIA. Workshop on ultrafine aerosols at workplaces. Held August 2002 in Germany. 208 pp. Available at: https://www.cdc.gov/niosh/topics/nanotech/. [Go to Nanotechnology Topic Page. Report is listed in section Non-US Governmental Resources]
[Many articles are available electronically through MIT Libraries]
- Chen HH, Yu C, Ueng TH, Chen S et al. Acute and subacute toxicity study of water soluble polyalkylsulfonated C60 in rats. Toxicol Pathol 26:143-151 1998.
- Cui D, Tian F, Ozkan CS, Wang M, Gao H. Effect of single wall carbon nanotubes on human HEK293 cells. Toxicol Lett 155:73-85 2005.
- Derfus AM, Chan WC, Bhatia SN. Probing the cytotoxicity of semiconductor quantum dots. Nano Lett 4:11-18 2004.
- Donaldson K, Aitken R, Tran L, et al. Carbon nanotubes: a review of their properties in relation to pulmonary toxicology and workplace safety. Toxicol Sci 92:5-22 2006.
- Goodman CM, McCusker CD, Yilmaz T, Rotello VM. Toxicity of gold nanoparticles functionalized with cationic and anionic side chains. Bioconjugate Chem 15:897-900 2004.
- Helland A, Wick, P, Koehler A, Schmid K, Som, C. Reviewing the Environmental and Human Health Knowledge Base of Carbon Nanotubes. Env Hlth Perspec 115:1125-1131 2007
- Lademann J, Weigmann HJ, Rickmeyer C, Barthelmes H et al. Penetration of titanium dioxide microparticles in a sunscreen formulation into the horny layer and the follicular orifice. Skin Parmacol Appl Skin Physiol 12:247-256 1999.
- Lam CW, James JT, McCluskey R, Hunter RL Pulmonary toxicity of single-wall carbon nanotubes in mice 7 and 90 days after intratracheal instillation. Toxicol Sci 77:126-134 2004.
- Li Z, Hulderman T, Salmen R, Chapman R, et al. Cardiovascular effects of pulmonary exposure to single-wall carbon nanotubes. Environ Hlth Perspec 115:377-382 2007.
- Maynard AD, Baron PA, Foley M, Shvedova AA et al. Exposure to carbon nanotube material: aerosol release during the handling of unrefined single-walled carbon nanotube material. J Toxicol Environ Hlth, Part A, 67:87-107 2004.
- Monteiro-Riviere NA, Nemanich RJ, Inman AO, Wang YY et al. Multi-walled carbon nanotube interactions with human epidermal keratinocytes. Toxicol Lett 155:377-384 2005.
- Oberdorster E. Manufactured nanomaterials (fullerenes) induce oxidative stress in the brain of juvenile largemouth bass. Enn Hlth Perspec 112:1058-1062 2004.
- Oberdorster G, Ferin J, Lehnert BE. Correlation between particle size, in vivo particle persistence and lung injury. Env Hlth Perspec 102 (suppl 5):173-179 2004a.
- Oberdorster G, Sharp Z, Atudorei V, Elder A et al. Extrapulmonary translocation of ultrafine carbon particles following whole-body inhalation exposure of rats. J Toxicol Environ Hlth Part A 65:1531-1543 2002.
- Oberdorster G, Sharp Z, Atudonrei V, Elder A et al. Translocation of inhaled ultrafine particles to the brain. Inhal Toxicol 16:453-459 2004b.
- Poland CA et al. Carbon nanotubes introduced into the abdominal cabiety of mice show asbesotos-like pathogenicity in a pilot study. Nat Nanotech 3:423-428 2008.
- Rymen-Rasmussen JP, Riviere JE, Monteiro-Riviere NA. Penetration of intact skin by quantum dots with diverse physicochemical properties. Toxicol Sci 91:159-165 2006.
- Sayes CM, Fortner JD, Guo W, Lyon D et al. The differential cytotoxicity of water-soluble fullerenes. Nano Lett 4:1881-1887 2004
- Sayes CM, Liang F, Hudson JL et al. Functionalization density dependence of single-walled carbon nanotubes cytotoxicity in vitro. Toxicol Lett 161:135-142 2006
- Shvedova AA, Kisin ER, Mercer R, Murray AR, et al. Unusual inflammatory and fibrogenic pulmonary responses to single-walled carbon nanotubes in mice. Am J Physiol Lung Cell Mol Physiol 289:L698-L708 2005.
- Shvedova AA et al. Inhalation vs. aspiration of single-walled carbon nanotubes in C57BL/6 mice: inflammation, fibrosis, oxidative stress, and mutagenesis. Am J Physiol Lung Cell Mol Physiol 295:L552-L565 2008.
- Shiohara A, Hshino A, Hanaki K, Suzuki K, et al. On the cyto-toxicity caused by quantum dots. Microbiol Immunol 48:669-675 2004.
- Takagi A et al. Induction of mesothelioma in p53+/- mouse by intraperitoneal application of multi-wall carbon nanotube. J Toxicol Sci 33:105-116 2008.
- Tinkle SS, Antonini JM, Rich BA, Roberts JR et al. Skin as a route of exposure and sensitization in chronic beryllium disease. Env Hlth Perspec 111:1202-1208 2003.
- Wang J et al. Time dependent translocation and potential impairment on central nervous system by intranasally instilled TiO2 nanoparticles. Toxicol 254:82-90 2008
- Warheit DB, Laurence BR, Reed KL, Roach DH, et al. Comparative pulmonary toxicity assessment of single-wall carbon nanotubes in rats. Toxicol Sci 77:117-125 (2004)
- Warheit DB, Webb TR, Colvin VC, et al. Pulmonary bioassay studies with nanoscale and fine-quartz particles in rats: toxicity is not dependent upon particle size but on surface characteristics. Toxicol Sci 95:270-280 2007.
- Warheit DB, Webb TR, Sayes CM et al. Pulmonary instillation studies with nanoscale TiO2 rods and dots in rats: toxicity is not dependent upon particle size and surface area. Toxicol Sci 91:227-236 2006.
Perchloric acid is a clear odorless liquid that is stable at room temperature. It is highly corrosive to all tissues and a strong oxidizer that reacts violently with a wide variety of substances, including organic materials, alcohols, amines, strong acids, strong bases, etc. Contact with wood, paper, and other cellulose products may lead to explosions. Avoid heat as it may form explosive peroxides at elevated temperatures.
Warning: Heated Perchloric Acid can only be used in a fume hood with a functioning water washdown. EHS has one of these hoods and there are others on campus. Contact EHS at 617-452-3477 if you need access to such a hood.
Before working with perchloric acid, review the Standard Operating Procedure.
Decommissioning Fume Hoods: All fume hoods and related ductwork should be checked for explosive perchlorates before dismantling these systems. Call the EHS Office at 617-452-3477 to conduct this test.
General Information
- Peroxide forming chemicals include many common solvents and reagents which are known to form organic peroxides on exposure to air (THF, Ethers, IPA, Dioxanes, Styrene, 2-Hexanol, etc)
- Highly flammable, low-power explosives that are very sensitive to shock, sparks, elevated temperatures, light, strong oxidizing and reducing agents, and friction, such as a cap being twisted open
- Distillation, evaporation or other concentration of some peroxide-forming chemicals can present a high risk of explosion
- May be inhibited or uninhibited (this will likely be indicated on the chemical container)
- Inhibition slows, but does not eliminate peroxide formation
- BHT, hydroquinone and diphenylamine are frequently used inhibitors
- The Peroxide Forming Chemicals SOP (requires certificate login) includes key dates for safe usage of chemical & allowable peroxide levels for waste disposal (i.e. </=20ppm)
Before Purchase
- Read MIT EHS SOP on Peroxide Forming Chemicals (requires certificate login).
- Determine the Group of the chemical based on the potential of peroxide formation.
- Determine amount you need and check inventory before ordering.
- Order only what you need. They have a short shelf life.
- Determine if inhibited chemicals can be used.
Upon Receiving Chemical
- Check for manufacturer’s expiration date & inhibitor info on the container
- Put received date on container.
- Use Avery Label #5160 for small bottle labels
- Use Avery Label #5164 for large bottle labels
- Add information to inventory.
- Store away from light, in a flammable storage cabinet, a flammable storage refrigerator, or other appropriate location/container.
- Indicate at storage location the presence of peroxide formers. (best practice)
- Use or Dispose of opened product (without testing) by manufacturer’s expiration date, OR based on receive date, if this is reached first, as indicated below:
- within 24 hours for un-inhibited chemicals in Group C (SOP)
- within 1 year for inhibited chemicals in Group C (SOP)
- within 3 months for chemicals in Group A (SOP)
- within 1 year for all chemicals in Group B & D (SOP)
- within 5 years for 2-Propanol / Isopropanol (IPA)
- Use or Dispose of unopened product (without testing):
- by manufacturer’s expiration date, OR
- within 12 months of receive date for all chemical Groups in SOP, if this is reached first
- Test containers for peroxides if they are beyond the recommended dates or if no dates are indicated on bottles in inventory.
- Examine bottle. If solids or crystals have formed do not attempt to test. Contact EHS (617) 452-3477 or environment@mit.edu.
- No need to test waste streams prior to disposal request, provided the concentration is <25%, by volume, of total waste stream (not IPA streams)
- Peroxide test strips are available from JT Baker (4416-01) through VWR
- Examine bottle carefully for possible crystals or particles in bottle or around the cap
- Lab should test containers before use if the expiration dates have been reached or if containers are no longer wanted and if the waste stream is >25% by volume, concentration of a peroxide forming chemical (not applicable to IPA waste streams)
- If </= 20 ppm, place red tag on container, indicate peroxide levels, and request disposal or bring to MAA
- If > 20 ppm, contact EHS (617) 452-3477 or environment@mit.edu.
- If at any time a researcher does NOT feel comfortable testing the container they should not attempt this and should contact EHS for assistance.
Piranha solutions are strong oxidizers used to remove small amounts of organic residues from electronic components. The most commonly used solution at MIT is a 3:1 mixture of sulfuric acid and hydrogen peroxide. The solutions are mixed together just before use and the reaction is extremely exothermic. Solution temperatures quickly rise to greater than 100 degrees C and generate significant quantities of gasses.
Piranha solutions are incompatible with other acids and organic materials such as alcohols and photoresists. The solutions are very corrosive to eyes, skin, and respiratory tract.
There have been multiple incidents in MIT labs where containers have ruptured due to the use of non-venting caps or mixing spent piranha with incompatibles such as isopropanol. In one instance, the glass bottle exploded and scattered glass throughout the lab. Fortunately, there was no one in the lab at the time of the explosion.
Piranha solutions should never be used in airtight containers. Vented caps should always be used and are available at no charge from the EHS Office. Piranha waste should never be mixed with other chemicals.
Before using this material, consult the detailed Chemical Fact Sheet for Piranha Solutions.
Polychlorinated Biphenyl (PCBs) refer to a class of chemicals consisting of 2 aromatic hydrocarbon rings (phenyls), where each hydrogen position on the carbon ring can be substituted with a chlorine atom. As the number of chlorine atoms on the ring increase so does the stability and thermal resistance properties.
- PCBs have joined a class of regulated materials called PBTs: persistent, bio-accumulative, and toxic chemicals
- PCBs do not degrade readily in the environment (persistent)
- PCBs concentrate in the fatty tissues of organisms, and doses are amplified with each step in the food chain (bio-accumulative)
- PCBs can cause chloracne
Although MIT made a concerted effort to dispose of PCB containing items and electrical equipment in the late 1980s, it is possible that an item pre-dating 1980 may surface when a space is cleaned for a lab move or a renovation. If you are unsure of the date of manufacture of any oil-containing equipment, please contact EHS.
For a comprehensive review of pyrophoric and water reactives materials, please review the SOP (certificate required).
Pyrophoric substances are liquids, solids, or gases that will ignite spontaneously in air at or below 130°F. To receive the pyrophoric classification under GHS a chemical must ignite within 5 minutes in air. However, chemicals that ignite after 5 minutes also pose a significant risk to users and should be handled as pyrophoric.
Water-reactive substances are substances that react with water or moisture to release a gas that is either flammable or a health hazard. When water contacts a water-reactive substance, enough heat may be generated to cause spontaneous combustion or an explosion. The guidelines on this page refer to water-reactive substances that have a risk of igniting on contact with moisture, not those that only release toxic gases.
A laboratory specific SOP is required for use of pyrophoric materials. Contact your DLC’s EHS Coordinator or the EHS Office for assistance.
If your lab plans to, or currently uses, reactive lithium and / or sodium compounds it is recommended that you ensure the appropriate extinguishing agent is available; for example, a Class D extinguisher, sand or a Met-L-X or Lith-X suppression material.
Many factors must be considered when determining what controls are required, including but not limited to the specific pyrophoric chemical(s) being used, type of application, and other hazards. For example, semiconductor research can involve pyrophoric materials that are also highly toxic, requiring additional controls. Contact your EHS Coordinator or the EHS Office for more specific guidance on appropriate controls based on your lab’s research.
Depending on the materials and process, pyrophoric and water-reactive materials should be used in a chemical fume hood (over a spill tray) using techniques that prevent the material from contacting air or in an inert-atmosphere glove box according to the manufacturer’s recommendations.
Before using pyrophoric reagents refer to the Aldrich Technical Bulletins AL-164 and AL-134, which provide detailed instructions on using standard syringe and double-tipped needle transfer techniques to prevent contact with air. Some pyrophoric and water-reactive materials must be handled in a gas-tight syringe to prevent exposure to air.
Flame resistant (FR) lab coats are required when handling pyrophoric substances, including chemicals that release flammable gases that may ignite spontaneously and self-heating chemicals that may catch fire outside of a glove box. FR lab coats should also be worn when working with chemicals that react violently with water or release flammable gas, or when performing potentially vigorous reactions.
Protective eyewear is required when handling pyrophoric and water-reactive materials. Fully enclosed safety goggles or a face shield are preferred, as they offer greater facial protection than safety glasses.
Gloves are required when handling pyrophoric and water-reactive materials. It is recommended that Nomex gloves be worn between two pairs of nitrile gloves for fire protection purposes.
Clothing made from polyester and other synthetic fabrics and loose clothing should not be worn. Always wear long pants and closed toe shoes within the lab. Loose or long hair should be tied back to prevent ignition in the event of a flash fire.
The best way to determine if the substance you are working with is pyrophoric or water reactive is to review the Safety Data Sheet. Safety Data Sheets for all chemicals in a laboratory space must be immediately available. Safety Data Sheets should be updated, reviewed periodically, and used as part of lab specific training.
Common pyrophoric materials include metal hydrides, non metal hydrides, metal halides, alkali metals, metal carbonyls, and metal powders.Note that this list includes examples of pyrophoric and water-reactive materials but is not comprehensive.
Downloadable PDF with hazard details
Many metal powders present special storage and handling concerns when finely divided, including hazards such as air- or water-reactivity or explosive dust generation. Whether a given metal powder exhibits these properties depends on multiple factors, including but not limited to particle size, surface area, moisture level, purity, etc.
Please contact your EHS Coordinator or the EHS Office for assistance when working with small-particle-size metal powders.
Excess pyrophoric chemicals should be treated as hazardous waste. Due to their properties special procedures may be required for waste collection and labs may incur disposal fees based on factors outlined below.
Contact EHS if several bottles are removed from storage at one time, as a fee may be applied depending on the volume. The more toxic and hazardous the chemical and the larger the bottle, the higher the cost tends to be.
Nonreturnable pyrophoric gas cylinders will also incur a cost at the time of disposal. Contact EHS for disposal rates and information on the removal process.
Certain metal powders, such as fine aluminum powder, should be submerged in oil prior to waste collection from the lab. Debris with aluminum powder may be collected with a thin coating of oil and kept separate from other debris waste streams.
Reactive metals, such as lithium, potassium and magnesium, should also be submerged under oil and handled as hazardous waste. Contact EHS for additional guidance.
Best Practices for Specific Chemicals
Aqua Regia is a fresh mixture of hydrochloric and nitric acids used to etch metals and clean glassware. It is very corrosive to skin and respiratory tract.
It needs to be mixed fresh for each use and evolves gasses which have caused many accidents and container ruptures. It should be used only when absolutely necessary. For detailed use instructions, you must develop your own standard operating procedure for your process by reviewing the Aqua Regia Chemical Factsheet.
Asbestos is a naturally occurring mineral fiber extensively used in building materials from the 1930s until the 1970s. It is resistant to heat, mechanical stress, and water. Asbestos fibers are only a hazard when they become airborne and can be inhaled.
Learn more about the Asbestos Program
Beryllium metal and its alloys are used in a wide variety of industrial products because they are light and resistant to heat, stress, and strain. Beryllium is highly toxic to the lungs and is a confirmed human carcinogen. All procedures that may be an exposure hazard should be evaluated by the EHS Office to insure that air concentrations are within acceptable levels. The ACGIH TLV for beryllium is 0.05 ug/m3. The OSHA PEL is 0.2 ug/m3.
All employees with potential for exposure can enroll in the annual medical surveillance program sponsored by the MIT Medical Department.
For additional information about safe work practices (including use of a respirator, gloves, clothing, etc), consult the MIT Beryllium Program and Procedures.
The inhalation of dust, fumes, or mists containing beryllium or beryllium compounds present a very serious health hazard. Laboratory processes that can produce fumes or inhalable dust include heating, grinding, and machining of beryllium and its alloys.
In humans, beryllium causes both acute and chronic lung disease and lung cancer. Acute beryllium disease has been seen after brief exposures to soluble beryllium compounds. Symptoms range from a mild inflammation of nasal passages to bronchitis and lung inflammation.
Chronic beryllium disease is characterized by lung fibrosis (scarring) and inflammation, causing breathlessness upon exertion, weakness, chest pain, enlarged heart, and ultimately death. Beryllium has been documented to cause lung cancer in industrial beryllium production facilities. Beryllium can also cause allergic skin reactions.
To work safely with beryllium, all labs and shops must do the following:
- All procedures that potentially generate beryllium particulates, such as heating or machining or aerosols of beryllium salts, must be evaluated by the EHS Office to insure that air levels are safe.
- All researchers working with beryllium in a manner that creates airborne exposure can enroll in the Beryllium Surveillance Program at MIT Medical by calling (617) 452-3477. The program is voluntary and free.
- Standard operating procedures for specific operations should be established before working with beryllium and its compounds. These will normally include the use of fume hoods or local exhaust ventilation.
- Prior to working with beryllium, employees must receive training from their supervisor. Beryllium users must also complete either Chemical Hygiene or Hazard Communication training and Managing Hazardous Waste training.
The following resources and detailed information is referred to in the Cryogen Safety web course (certificate required).
Best practice for dispensing liquid from a low pressure container to a dewar:
- Don a face shield and safety glasses, cryogenic gloves, long pants without cuffs, closed-toed shoes, and a laboratory coat.
- Next connect a transfer line to the liquid valve, if one is not already present, making sure the fittings match. Please note that the valve will be labeled. The transfer line should have a phase separator attached to reduce turbulence and the release of gas while filling.
- Check the pressure in the cylinder. It should read approximately 22 pounds per square inch. Position the Dewar on the floor at the base of the cylinder, or on some other support below waist level and insert the transfer line into the Dewar. The end of the transfer line should extend to the bottom, or just off the bottom, of the Dewar. Keep bystanders at least four feet away while filling in case of splashing.
- Open the liquid valve one half to three quarters of a turn to begin cooling down the transfer hose and adding the cryogen to the Dewar. The warm hose and Dewar will vaporize the cryogen as it cools and this could create splashing particularly if it is added too quickly. The pressure in the container will drive the liquid out through the valve.
- Once the hose and Dewar have cooled, open the liquid valve to obtain the desired rate of flow. However, if you fully open the valve, be sure to close it a quarter turn. A fully opened valve may freeze in that position causing a spill. A good flow rate is typically evident by a moderate vapor trail coming from the mouth of the Dewar. Listen for the change in sound as the Dewar fills – a higher pitch indicates the Dewar is getting full.
- When full, close the liquid valve. Remove the transfer line but be careful not to drop it or allow the phase separator to hit a solid object which will cause it to break. Watch out for any cryogen that continues to spill out of the transfer hose. Finally, place the top on the Dewar, pushing it all the way on and then pulling it up so that it is loose.
Best practice for dispensing gas from a high pressure container to equipment or system:
- Don cryogenic gloves, safety glasses, long pants without cuffs, closed-toed shoes, and a laboratory coat.
- Check the pressure in the cylinder. It should be approximately 230 pounds per square inch, but this will vary with the gas dispensed.
- Next connect the inlet of a suitable regulator to the gas use valve or a transfer line from this valve to an appropriate wall mounted regulator. Please note that the gas withdrawal valve will be labeled. The regulator should be designed for use with cryogens and adjustable over the desired pressure range.
- The outlet of the regulator is connected to the system receiving the gas using the appropriate transfer line – in this case it’s a dedicated gas line.
- Next close the regulator valve and open the gas use valve. Adjust the gas regulator to deliver the gas at the desired pressure, for example, 90 pounds per square inch. At this point you may begin withdrawing gas.
- In applications where large volumes of gas will be withdrawn from the container, the pressure building valve will be opened. This valve operates an internal circuit that allows more liquid to vaporize then would naturally occur through evaporation alone. The vendor supplying the container generally knows your application and opens or closes this valve when delivered.
The transportation of cryogenic containers in elevators represents a potential asphyxiation risk if researchers become trapped in an elevator with a container of cryogen. If a passenger elevator must be used, the first person rolls the container into the elevator, posts a clearly visible sign that warns staff and students not to enter the elevator. The first person pushes the elevator button for the appropriate floor and immediately gets off the elevator. The second person meets the elevator, removes the container and the sign.
This table lists the change in volume as the gas transitions from liquid to gas at room temperature. The resulting pressure that would be generated inside a container from trapped liquid under these conditions is also listed.
Helium | Nitrogen | Oxygen | CO2 | |
---|---|---|---|---|
Boiling point °F (1 @atm) | -452 | -321 | -297 | -108 |
Change in volume as liquid expands to gas at room temperature (liquid-to-gas expansion ratio) | 780 | 710 | 875 | 790 |
Pressure generated from trapped liquid allowed to warm to room temperature | 10,950 psig | 10,230 psig | Not Specified | Not Specified |
Note 1: Although CO2, which has a slightly higher boiling is technically not cryogenic liquid but has similar properties and is often included in this category. (Note: Source Argonne National Laboratory)
Resources / Additional Information
- LN2 Ice Cream Safety Plan Template
- Cryogenic Liquids SOP (certificate required)
- Cryogen Valve Diagrams
- Cryogen Safety Web Course Narrative
- Safetygram – Helium
- Safetygram – Oxygen
Cyanide salts (sodium and potassium) have a white crystalline or powder appearance. They are highly toxic by inhalation, ingestion, and can even be absorbed through the skin. As little as 50 mg can be fatal to a human being. Mixing dry salts with atmospheric moisture or with acids can release poisonous hydrogen cyanide gas which can be fatal.
MIT Procurement will not allow you to purchase cyanide salts unless the EHS Office approves your order. You must review and follow all the Cyanide Salts Safety Guidelines.
Formaldehyde is classified by OSHA as a Particularly Hazardous Substance, a probable carcinogen, and a respiratory and skin sensitizer. It has a strong odor detectable at 0.04 to 1 parts per million (ppm). The OSHA 8 hour Permissible Exposure Limit is 0.75 ppm. The 15 minute Short Term Exposure Limit is 2 ppm.
Formaldehyde can be used safely provided that the following precautions are followed:
- Use in a fume hood or other ventilated enclosure such as a dissection hood or ventilated downdraft table unless very dilute or small quantities.
- Wear gloves with good resistance to formaldehyde, such as the disposable nitrile Best NDex glove – Latex gloves provide short term splash resistance only and should generally not be worn for formaldehyde work.
- All formaldehyde waste should be collected and disposed of as hazardous waste.
- The Chemical Hygiene Lab Specific Training for your lab should cover formaldehyde hazards and safe use practices.
- Call the EHS Office (617-452-3477) if you can smell formaldehyde during your procedures.
- Make an appointment with the MIT Medical Department (617-253-4481) if you experience any symptoms of eye, nose, or throat irritation during your work with formaldehyde.
MIT must identify all laboratory activities that are above the OSHA action level or short term exposure level (STEL) through initial air monitoring and provide training, medical surveillance, and engineering and work practice controls if air levels warrant it. The Industrial Hygiene Program (IHP) in the EHS Office has performed extensive air sampling for formaldehyde during a variety of lab activities such as animal perfusion, dissections, and tissue fixation and found the results to be below OSHA levels provided that suitable exhaust ventilation is used.
With proper exhaust ventilation, you should not detect any odors from formaldehyde work nor experience any symptoms of exposure such as eye tearing or throat irritation. If you do, please contact EHS immediately at (617) 452-3477 for an evaluation.
EHS sends a questionnaire annually to laboratory EHS Representatives to survey formaldehyde use and conducts air sampling of procedures where there may be a potential for exposure. Notify EHS for an evaluation if your procedures change and you work with large quantities of formaldehyde, perform animal perfusions, or do extensive tissue dissection work.
Hydrofluoric acid (HF) is a particularly hazardous substance, like many acids, but has added dangers that make it especially dangerous. It is less dissociated than most acids and deeply penetrates the skin. Symptoms of exposure may be delayed for up to 24 hours, even with dilute solutions. HF burns affect deep tissue layers, are extremely painful and disfiguring. The highly reactive fluoride ion circulates throughout the body and can cause multiple organ toxicity, including heart arrhythmias and death, if not treated.
Any suspected skin exposures to HF should be immediately flooded with water, decontaminated with calcium gluconate gel, and be treated at MIT Medical”.
“In case of:
- Large area of skin exposure (greater than the palm of the hand) and the HF concentration is greater than 5%
- Eye exposure
- Inhalation exposure
- Ingestion
Immediately call 100 or 617-253-1212, ask for Advanced Life Support (ALS) Ambulance, follow appropriate irrigation protocol and go directly to the hospital.
All laboratories using HF must have unexpired calcium gluconate decontamination gel on hand. You may obtain it from the EHS Office by completing this form.
Calcium Gluconate Gel Request Form
All employees are required to be trained by the EHS Office before beginning work with HF. The training covers safe use, personal protective equipment, and decontamination procedures. The training can be taken on the web or in the classroom. Visit Atlas and select Learning Center to search and register for the training.
Isoflurane is an anesthetic gas that is widely used at MIT. Isoflurane is a halogenated anesthetic gas and one of the most commonly used inhalation anesthetics in experimental and veterinary animal procedures.
There are many different set-ups in laboratories that potentially will expose researchers and employees to isoflurane. Acute exposure with isoflurane includes headaches, dizziness, fatigue, temporary blurring of vision, and nausea. Chronic health effects include a slight increase in risk for miscarriages, liver and kidney disease, and possible reproductive effects. Currently, there is no established exposure limit specific to exposure to isoflurane. The MIT EHS Office is using 2 ppm as an 8-hour time-weighted average (TWA). For additional information about isoflurane safe work practices, please read the Standard Operating Guideline, Isoflurane Safety Guidelines (certificate required).
This document can also be located on the Forms & SOP’s page; search for “Isoflurane Safety Guidelines”.
Lead can be found in many places on campus including paint, solder, ceramic products, and water. Lead and its compounds are toxic and present a health hazard when ingested or inhaled. Once absorbed it is carried throughout the body by the bloodstream to other organs.
Excessive lead levels can result in damage to the brain, kidney, CNS, blood, and reproductive systems. Lead is extremely hazardous to children because it is easily absorbed into their bodies and interferes with the developing brain, central nervous systems, and other organs. Lead is excreted mainly through the urinary and GI tract. Not all the lead is excreted though; some is absorbed in the bones.
MIT is committed to providing students and employees with safe work environments free from any health hazards and we comply with pertinent Federal and State guidelines and regulations. Such regulations require the identification of lead-containing materials, maintaining painted surfaces, effective and proper abatement when necessary, and proper disposal of waste generated by the abatement project.
Lithium and sodium compounds include (but are not limited to): butyllithium, lithium aluminum hydride, lithium borohydride, lithium hydride, lithium nitride, sodium aluminum hydride, sodium borohydride, sodium hydride.
The EHS Office strongly recommends the use of a process safety procedure that identifies the appropriate personal protective equipment (PPE), engineering controls, waste management requirements, and emergency response steps to ensure those working with these reactive materials are aware of the hazards.
If your lab plans to, or currently uses, reactive lithium and / or sodium compounds it is recommended that you ensure the appropriate extinguishing agent (such as a Class D extinguisher, sand or a Met-L-X or Lith-X suppression material) are available.
For specific information, refer to Fire Safety. Please note that the list of compounds below is not inclusive. Refer to the Safety Data Sheet (SDS) and/or contact the EHS Office for assistance.
Upon completion of your experiment using lithium or sodium metals or powders, specifically, follow these guidelines or contact the EHS Office for assistance in preparing the waste or surplus materials for hazardous waste pick-up:
- Within the glove box or controlled environment, containerize your waste materials and submerge them in oil.
- Remove the container of waste from the glove box, label it with a red tag, spell out the constituents, indicate Ignitable/Reactive as the associated hazards, date the container, and place it in your lab’s SAA.
- Upon dating, place a waste collection pickup request online for removal from the lab within 3-days.
Mercury is a naturally occurring element that is found in air, water, and soil. It exists in several forms: elemental or metallic mercury, inorganic mercury compounds, and organic mercury compounds.
- When elemental mercury is spilled or a device containing mercury breaks, the exposed mercury volatilizes at room temperature and becomes an odorless toxic vapor. Mercury vapors will increase in warm or poorly-ventilated rooms or spaces.
- Mercury and its compounds penetrate the intact skin. Wear nitrile, PVC, or natural rubber gloves for elemental mercury. For organo-alkyl compounds, use Silver Shield or 4H gloves and an outer glove of heavy-duty nitrile or neoprene.
- The nervous system is very sensitive to all forms of mercury. Methylmercury and metallic mercury vapors are more harmful than other forms because more mercury in these forms reaches the brain.
- Exposure to high levels of metallic, inorganic, or organic mercury can permanently damage the brain, kidneys, and developing fetus.
Nanomaterials are defined by the American Society for Testing and Materials as a material with two or three dimensions between 1 to 100 nm. They can be composed of many different base materials such as carbon or silicon, and metals such as gold, cadmium, and selenium. They can also have different shapes: such as nanotubes, nanowires, or crystalline structures such as quantum dots and fullerenes.
Nanomaterials often exhibit very different properties from their respective bulk materials: greater strength, conductivity, and fluorescence, among other properties.
Nanoparticles are generally similar in size to proteins in the body and are considerably smaller than many cells in the body. Human alveolar macrophages are 24 um in diameter and red blood cells are 7-8 um in diameter. Cells growing in tissue culture will pick up most nanoparticles.
Particles in the nanometer size range do occur both in nature and as an incidental byproduct of existing industrial processes. Nanosized particles are part of the range of atmospheric particles generated by natural events such as volcanic eruptions and forest fires. They also form part of the fumes generated during welding, metal smelting, automobile exhaust, and other industrial processes. One concern about small particles that are less than 10 um is that they are respirable and reach the alveolar spaces of the lungs.
The ability to be taken up by cells is being used to develop nanosized drug delivery systems and does not inherently indicate toxicity.
Quantum Dots
Quantum dots are nanocrystals containing 1,000 to 100,000 atoms and exhibiting unusual “quantum effects” such as prolonged fluorescence. They are being investigated for use in immunostaining as alternatives to fluorescent dyes. The most commonly used material for the core crystal is cadmium-selenium, which exhibits bright fluorescence and high photostability. Both bulk cadmium and selenium are toxic to cells. One of the primary sites of cadmium toxicity in vivo is the liver.
Carbon Nanotubes
Carbon Nanotubes (CNT) can have either single or multiple layers of carbon atoms arranged in a cylinder. The dimensions of typical single-wall carbon nanotubes (SWCNT) are about 1-2 nm in diameter by 0.1 um in length. Multiple wall carbon nanotubes (MWCNT) are 20 nm in diameter and 1 mm long.
CNT may behave like fibers in the lung. They have properties very different from bulk carbon or graphite. They have great tensile strength and are potentially the strongest, smallest fibers known. CNT have been tested in short term animal tests of pulmonary toxicity and the results suggest the potential for lung toxicity though there are questions about the nature of the toxicity observed and the doses used.
Fullerenes
Fullerenes are another category of carbon-based nanoparticles. The most common type has a molecular structure of C60 which takes the shape of a ball-shaped cage of carbon particles arranged in pentagons and hexagons. Fullerenes have many potential medical applications as well as applications in industrial coatings and fuel cells, so a number of preliminary toxicology studies have been done with them.
The toxicity of most nanomaterials is currently unknown. Studies suggest that the levels of toxicity depend on the base material of the nanoparticle, its size and structure, and its substituents and coatings.
The preliminary conclusions to be drawn from the toxicology studies to date is that some types of nanomaterials can be toxic, if they are not bound up in a substrate and they are available to the body. Multiple government organizations are working to fund and assemble toxicology information on these materials. In the interim, MIT researchers must use procedures that prevent inhalation and dermal exposures because at this time nanotoxicology information is limited.
Handling Nanoparticles
Nanomaterials of uncertain toxicity can be handled using the same precautions currently used at MIT to handle toxic materials: use of exhaust ventilation (such as fume hoods and vented enclosures) to prevent inhalation exposure during procedures that may release aerosols or fibers and use of gloves to prevent dermal exposure. The EHS Office will continue to review health and safety information about nanomaterials as it becomes available and distribute it to the MIT community.
Changes in Technology
The current nanotechnology revolution differs from past industrial processes because nanomaterials are being engineered and fabricated from the “bottom-up”, rather than occurring as a byproduct of other activities. The nanomaterials being engineered have different and unexpected properties compared to those of the parent compounds. Since their properties are different when they are small, it is expected that they will have different effects on the body and will need to be evaluated separately from the parent compounds for toxicity.
Currently, nanomaterials have a limited commercial market. Some nanomaterials are used as catalyst supports in catalytic converters; nanosized titanium dioxide particles are used as a component of sunscreens; carbon nanotubes have been used to strengthen tennis rackets; components in silicon chips are reaching the 45 to 65 nm range.
Research and industrial labs are working at the intersection of engineering and biology to extend uses to medicine as well as all areas of engineering. The impact is expected to revolutionize these areas. Government agencies in the US and Europe are beginning to fund toxicology research to understand the hazards of these materials before they become widely available.
Translocation in the Body
Once in the body, some types of nanoparticles may have the ability to translocate and be distributed to other organs, including the central nervous system. Silver, albumin, and carbon nanoparticles all showed systemic availability after inhalation exposure.
Significant amounts of 13C labeled carbon particles (22-30 nm in diameter) were found in the livers of rats after 6 hours of inhalation exposure to 80 or 180 ug/m3 (Oberdorster et al. 2002). In contrast, only very small amounts of 192Ir particles (15 nm) were found systemically. Oberdorster et al. (2004) also found that inhaled 13 C labeled carbon particles reached the olfactory bulb and also the cerebrum and cerebellum, suggesting that translocation to the brain occurred through the nasal mucosa along the olfactory nerve to the brain.
The ability of nanomaterials to move about the body may depend on their chemical reactivity, surface characteristics, and ability to bind to body proteins.
Titanium Dioxide Nanoparticles
Nanoscale titanium dioxide has shown very different properties from the micron-scale material in tests of lung toxicity. In addition, 14 to 40 nm titanium dioxide produced lung cancer in rats at doses of 10 mg/m3; micron-sized dust produced cancer only at very high doses (250 mg/m3). Based on these results the National Institute of Occupational Safety and Health (NIOSH) issued a recommended safe occupational exposure limit of 0.1 mg/m3 for nanoscale material and 1.5 mg/m3 for micron size material.
The International Agency for Research on Cancer (IARC) has also determined that titanium dioxide is a category 2B carcinogen: possibly carcinogenic to humans. Last year Wang et al (2008) showed that nanoscale titanium dioxide when inhaled could travel to the brain by way of olfactory neurons. Once in the brain, it caused oxidative stress and neuronal degeneration in several areas, including the hippocampus which is involved with short-term memory.
Nanoscale titanium dioxide joins several other types of nanomaterials (manganese oxide, nanocarbon, and some viruses) that can enter the brain directly by means of the olfactory pathway from the nose.
Skin Penetration
There is currently no consensus about the ability of nanoparticles to penetrate through the skin. Particles in the micrometer range are generally thought to be unable to penetrate through the skin. The outer skin consists of a 10 um thick, tough layer of dead keratinized cells (stratum corneum) that is difficult to pass for particles, ionic compounds, and water soluble compounds. Tinkle et al. (2003) found that 0.5 and 1 um dextran spheres penetrated “flexed” human skin in an in vitro experiment.
Particles penetrated into the epidermis and a few entered the dermis only during flexing of the skin. Particles 2 and 4 um in diameter did not penetrate. Rymen-Rasmussen et al. (2006) also found that quantum dots penetrated through pig skin and into living dermis using an in vitro pig skin bioassay which is considered a good model for human skin.
Micronized titanium dioxide (40 nm) is currently being used in sunscreens and cosmetics as sun protection. The nm particles are transparent and do not give the cosmetics the white, chalky appearance that coarser preparations did. The nm particles have been found to penetrate into the stratum corneum and more deeply into hair follicles and sweat glands than um particles though they did not reach the epidermis layer and dermis layers (Laddeman et al., 1999).
There is also a concern that nm titanium dioxide particles have higher photo-reactivity than coarser particles and may generate free radicals that can cause cell damage. Some manufacturers have addressed this issue by coating the particles to prevent free radical formation. The FDA has reviewed available information and determined that nm titanium dioxide particles are not a new ingredient but a specific grade of the original product (Luther, 2004).
The MIT EHS Office considers nanoparticles that have the potential for release into the air to be handled as particularly hazardous substance because their toxicity is, for the most part, unknown and early studies have been suggestive of toxic effects. In the future, many types of nanoparticles may turn out to be of limited toxicity but precaution must be used until we know more. The following best practices should be followed:
- Work with nanoparticles that may release particles should be conducted in enclosures, fume hood, glove boxes, and other vented enclosures.
- All work should be done with gloves (at a minimum disposable nitrile gloves)
- Currently, nanoparticles and solutions containing them are being disposed of as hazardous waste. Label all containers of nanomaterials (including waste) with the designation “nano”.
- Before work, review the Best Practices for Handling Nanomaterials in Laboratories
- Review the checklist for developing your laboratory Standard Operating Procedure for nanomaterials work
- Call the EHS Office at 617-253-0344 for exposure evaluation of experimental setups and additional information.
EHS has developed a training, Nanomaterials Health and Safety Course, which includes information on the toxicity of different types of nanomaterials and laboratory practices to prevent exposures.
If you have any questions after reviewing these materials, contact the EHS Office at environment@mit.edu or 452-3477. An EHS Officer can also visit your lab for a review of your procedures.
Nanomaterials can be handled in fume hoods, biosafety cabinets, and other exhausted enclosures. However, these hoods often have high air velocities that can be disruptive to handling dry, lightweight nanomaterials.
Laboratories in Mechanical Engineering and Center for Materials Science and Engineering have purchased a specially designed type of enclosure for handling nanopowders. This type of enclosure differs from a traditional fume hood in that the slots for exhausted air are located above the floor of the unit. Therefore air currents do not disturb the handling of light, fluffy nanopowders or nanotubes. These units were originally developed to enclose sensitive balances but can be used either to weigh nanomaterials or manipulate samples.
Contact EHS for vendors who supply these enclosures.
As nanotechnology emerges and evolves, potential environmental applications and human health and environmental implications are under consideration by the EPA and local regulators.
EPA has a number of different offices coordinating its review of this rapidly evolving technology. The EPA is currently trying a voluntary approach to testing and developing a stewardship program. There are currently no guidelines from the EPA specifically addressing the disposal of waste nanomaterials. It seems that regulation at some level is inevitable. Some political subdivisions, including the City of Cambridge, are already evaluating local regulation.
MIT is taking a cautious approach to nano waste management. It is our belief that regulation is inevitable. In order to better understand the potential volumes and characteristics of these waste streams, we are advising that all waste materials potentially contaminated with nanomaterials be identified and evaluated or collected for special waste disposal.
The following waste management guidance applies to nanomaterial-bearing waste streams consisting of:
- Pure nanomaterials (e.g., carbon nanotubes)
- Items contaminated with nanomaterials (e.g., wipes/PPE)
- Liquid suspensions containing nanomaterials
- Solid matrixes with nanomaterials that are friable or have a nanostructure loosely attached to the surface such that they can reasonably be expected to break free or leach out when in contact with air or water, or when subjected to reasonably foreseeable mechanical forces.
The guidance does not apply to nanomaterials embedded in a solid matrix that cannot reasonably be expected to break free or leach out when they contact air or water, but would apply to dusts and fines generated when cutting or milling such materials.
DO NOT put material from nanomaterial – bearing waste streams into the regular trash or down the drain. Before disposal of any waste contaminated with nanomaterial, call the EHS Office (45(617) 452-3477) for a waste determination.
Collect paper, wipes, PPE, and other items with loose contamination in a plastic bag or other sealing container stored in the laboratory hood. When the bag is full, close it, take it out of the hood and place it into a second plastic bag or other sealing container. Label the outer bag with the laboratory’s proper waste label. On the Contents section, note that it contains nano-sized particles and indicate what they are.
Currently, the disposal requirements for the base materials should be considered first when characterizing these materials. If the base material is toxic, such as silver or cadmium, or the carrier is a hazardous waste, such as a flammable solvent or acid, clearly they should carry those identifiers. Many nanoparticles may also be otherwise joined with toxic metals of chemicals. Bulk carbon is considered a flammable solid, so even carbon-based nanomaterials should be collected for determination as hazardous waste characteristics.
The EHS Office regularly seeks out new information regarding nanomaterials and will alert the MIT community about additional toxicology studies as they become available. We also request that MIT researchers alert us about studies that they learn so we can distribute them to the MIT community.
We would like to observe handling procedures in different labs so we can share good practice information within the MIT community. Many of the articles listed below can be accessed electronically through the MIT Libraries if an electronic subscription is available. Web sites are also provided where available.
Additional MIT Guidance
- Best Practices for Handling Nanomaterials in Laboratories
- Checklist for Nanomaterials Standard Operating Procedures
Web Sites
- Gradient Corp. Monthly EH&S Nano News
- National Institute for Occupational Safety and Health (NIOSH)
- National Nanotechnology Infrastructure Network (NNIN)
- National Center for Biotechnology Information (NCBI) Pub Med – Search for articles on nanoparticle toxicity
- Safe Nano (UK) – Regularly updated wensite on health and safety risks of nanotechnology with comments by toxicologists and regulators
- Borm P JA, Robbins D, Haubold S et al. The potential risks of nanomaterials: a review carried out for ECETOC. Part Fiber Toxicol 3:11-35 2006.
- Colvin VL. The potential environmental impact of engineered nanmoaterials. Nature Biotechnology 21:1166-1170 2003. [Note: Excellent and succinct overview of nanotoxicology.
- Oberdorster G, Oberdorster E, Oberdorster J. Nanotoxicology: An Emrging Discipline Evolving from Studies of Ultrafine Particles. Environmental Health Perspectives 113:823-839 2005.
- Health and Safety Executive (UK). Health effects of particles produced for nanotechnologies. Document EH75/6. 35 pp. December 2004. Available at: www.hse.gov.uk. [Search for EH75/6]
- Health and Safety Executive (UK). Nanoparticles: an occupational hygiene review. Research Report 274. 100 pp. 2004. Available at: www.hse.gov.uk. [Search for RR274]
- BIA. Workshop on ultrafine aerosols at workplaces. Held August 2002 in Germany. 208 pp. Available at: https://www.cdc.gov/niosh/topics/nanotech/. [Go to Nanotechnology Topic Page. Report is listed in section Non-US Governmental Resources]
[Many articles are available electronically through MIT Libraries]
- Chen HH, Yu C, Ueng TH, Chen S et al. Acute and subacute toxicity study of water soluble polyalkylsulfonated C60 in rats. Toxicol Pathol 26:143-151 1998.
- Cui D, Tian F, Ozkan CS, Wang M, Gao H. Effect of single wall carbon nanotubes on human HEK293 cells. Toxicol Lett 155:73-85 2005.
- Derfus AM, Chan WC, Bhatia SN. Probing the cytotoxicity of semiconductor quantum dots. Nano Lett 4:11-18 2004.
- Donaldson K, Aitken R, Tran L, et al. Carbon nanotubes: a review of their properties in relation to pulmonary toxicology and workplace safety. Toxicol Sci 92:5-22 2006.
- Goodman CM, McCusker CD, Yilmaz T, Rotello VM. Toxicity of gold nanoparticles functionalized with cationic and anionic side chains. Bioconjugate Chem 15:897-900 2004.
- Helland A, Wick, P, Koehler A, Schmid K, Som, C. Reviewing the Environmental and Human Health Knowledge Base of Carbon Nanotubes. Env Hlth Perspec 115:1125-1131 2007
- Lademann J, Weigmann HJ, Rickmeyer C, Barthelmes H et al. Penetration of titanium dioxide microparticles in a sunscreen formulation into the horny layer and the follicular orifice. Skin Parmacol Appl Skin Physiol 12:247-256 1999.
- Lam CW, James JT, McCluskey R, Hunter RL Pulmonary toxicity of single-wall carbon nanotubes in mice 7 and 90 days after intratracheal instillation. Toxicol Sci 77:126-134 2004.
- Li Z, Hulderman T, Salmen R, Chapman R, et al. Cardiovascular effects of pulmonary exposure to single-wall carbon nanotubes. Environ Hlth Perspec 115:377-382 2007.
- Maynard AD, Baron PA, Foley M, Shvedova AA et al. Exposure to carbon nanotube material: aerosol release during the handling of unrefined single-walled carbon nanotube material. J Toxicol Environ Hlth, Part A, 67:87-107 2004.
- Monteiro-Riviere NA, Nemanich RJ, Inman AO, Wang YY et al. Multi-walled carbon nanotube interactions with human epidermal keratinocytes. Toxicol Lett 155:377-384 2005.
- Oberdorster E. Manufactured nanomaterials (fullerenes) induce oxidative stress in the brain of juvenile largemouth bass. Enn Hlth Perspec 112:1058-1062 2004.
- Oberdorster G, Ferin J, Lehnert BE. Correlation between particle size, in vivo particle persistence and lung injury. Env Hlth Perspec 102 (suppl 5):173-179 2004a.
- Oberdorster G, Sharp Z, Atudorei V, Elder A et al. Extrapulmonary translocation of ultrafine carbon particles following whole-body inhalation exposure of rats. J Toxicol Environ Hlth Part A 65:1531-1543 2002.
- Oberdorster G, Sharp Z, Atudonrei V, Elder A et al. Translocation of inhaled ultrafine particles to the brain. Inhal Toxicol 16:453-459 2004b.
- Poland CA et al. Carbon nanotubes introduced into the abdominal cabiety of mice show asbesotos-like pathogenicity in a pilot study. Nat Nanotech 3:423-428 2008.
- Rymen-Rasmussen JP, Riviere JE, Monteiro-Riviere NA. Penetration of intact skin by quantum dots with diverse physicochemical properties. Toxicol Sci 91:159-165 2006.
- Sayes CM, Fortner JD, Guo W, Lyon D et al. The differential cytotoxicity of water-soluble fullerenes. Nano Lett 4:1881-1887 2004
- Sayes CM, Liang F, Hudson JL et al. Functionalization density dependence of single-walled carbon nanotubes cytotoxicity in vitro. Toxicol Lett 161:135-142 2006
- Shvedova AA, Kisin ER, Mercer R, Murray AR, et al. Unusual inflammatory and fibrogenic pulmonary responses to single-walled carbon nanotubes in mice. Am J Physiol Lung Cell Mol Physiol 289:L698-L708 2005.
- Shvedova AA et al. Inhalation vs. aspiration of single-walled carbon nanotubes in C57BL/6 mice: inflammation, fibrosis, oxidative stress, and mutagenesis. Am J Physiol Lung Cell Mol Physiol 295:L552-L565 2008.
- Shiohara A, Hshino A, Hanaki K, Suzuki K, et al. On the cyto-toxicity caused by quantum dots. Microbiol Immunol 48:669-675 2004.
- Takagi A et al. Induction of mesothelioma in p53+/- mouse by intraperitoneal application of multi-wall carbon nanotube. J Toxicol Sci 33:105-116 2008.
- Tinkle SS, Antonini JM, Rich BA, Roberts JR et al. Skin as a route of exposure and sensitization in chronic beryllium disease. Env Hlth Perspec 111:1202-1208 2003.
- Wang J et al. Time dependent translocation and potential impairment on central nervous system by intranasally instilled TiO2 nanoparticles. Toxicol 254:82-90 2008
- Warheit DB, Laurence BR, Reed KL, Roach DH, et al. Comparative pulmonary toxicity assessment of single-wall carbon nanotubes in rats. Toxicol Sci 77:117-125 (2004)
- Warheit DB, Webb TR, Colvin VC, et al. Pulmonary bioassay studies with nanoscale and fine-quartz particles in rats: toxicity is not dependent upon particle size but on surface characteristics. Toxicol Sci 95:270-280 2007.
- Warheit DB, Webb TR, Sayes CM et al. Pulmonary instillation studies with nanoscale TiO2 rods and dots in rats: toxicity is not dependent upon particle size and surface area. Toxicol Sci 91:227-236 2006.
Perchloric acid is a clear odorless liquid that is stable at room temperature. It is highly corrosive to all tissues and a strong oxidizer that reacts violently with a wide variety of substances, including organic materials, alcohols, amines, strong acids, strong bases, etc. Contact with wood, paper, and other cellulose products may lead to explosions. Avoid heat as it may form explosive peroxides at elevated temperatures.
Warning: Heated Perchloric Acid can only be used in a fume hood with a functioning water washdown. EHS has one of these hoods and there are others on campus. Contact EHS at 617-452-3477 if you need access to such a hood.
Before working with perchloric acid, review the Standard Operating Procedure.
Decommissioning Fume Hoods: All fume hoods and related ductwork should be checked for explosive perchlorates before dismantling these systems. Call the EHS Office at 617-452-3477 to conduct this test.
General Information
- Peroxide forming chemicals include many common solvents and reagents which are known to form organic peroxides on exposure to air (THF, Ethers, IPA, Dioxanes, Styrene, 2-Hexanol, etc)
- Highly flammable, low-power explosives that are very sensitive to shock, sparks, elevated temperatures, light, strong oxidizing and reducing agents, and friction, such as a cap being twisted open
- Distillation, evaporation or other concentration of some peroxide-forming chemicals can present a high risk of explosion
- May be inhibited or uninhibited (this will likely be indicated on the chemical container)
- Inhibition slows, but does not eliminate peroxide formation
- BHT, hydroquinone and diphenylamine are frequently used inhibitors
- The Peroxide Forming Chemicals SOP (requires certificate login) includes key dates for safe usage of chemical & allowable peroxide levels for waste disposal (i.e. </=20ppm)
Before Purchase
- Read MIT EHS SOP on Peroxide Forming Chemicals (requires certificate login).
- Determine the Group of the chemical based on the potential of peroxide formation.
- Determine amount you need and check inventory before ordering.
- Order only what you need. They have a short shelf life.
- Determine if inhibited chemicals can be used.
Upon Receiving Chemical
- Check for manufacturer’s expiration date & inhibitor info on the container
- Put received date on container.
- Use Avery Label #5160 for small bottle labels
- Use Avery Label #5164 for large bottle labels
- Add information to inventory.
- Store away from light, in a flammable storage cabinet, a flammable storage refrigerator, or other appropriate location/container.
- Indicate at storage location the presence of peroxide formers. (best practice)
- Use or Dispose of opened product (without testing) by manufacturer’s expiration date, OR based on receive date, if this is reached first, as indicated below:
- within 24 hours for un-inhibited chemicals in Group C (SOP)
- within 1 year for inhibited chemicals in Group C (SOP)
- within 3 months for chemicals in Group A (SOP)
- within 1 year for all chemicals in Group B & D (SOP)
- within 5 years for 2-Propanol / Isopropanol (IPA)
- Use or Dispose of unopened product (without testing):
- by manufacturer’s expiration date, OR
- within 12 months of receive date for all chemical Groups in SOP, if this is reached first
- Test containers for peroxides if they are beyond the recommended dates or if no dates are indicated on bottles in inventory.
- Examine bottle. If solids or crystals have formed do not attempt to test. Contact EHS (617) 452-3477 or environment@mit.edu.
- No need to test waste streams prior to disposal request, provided the concentration is <25%, by volume, of total waste stream (not IPA streams)
- Peroxide test strips are available from JT Baker (4416-01) through VWR
- Examine bottle carefully for possible crystals or particles in bottle or around the cap
- Lab should test containers before use if the expiration dates have been reached or if containers are no longer wanted and if the waste stream is >25% by volume, concentration of a peroxide forming chemical (not applicable to IPA waste streams)
- If </= 20 ppm, place red tag on container, indicate peroxide levels, and request disposal or bring to MAA
- If > 20 ppm, contact EHS (617) 452-3477 or environment@mit.edu.
- If at any time a researcher does NOT feel comfortable testing the container they should not attempt this and should contact EHS for assistance.
Piranha solutions are strong oxidizers used to remove small amounts of organic residues from electronic components. The most commonly used solution at MIT is a 3:1 mixture of sulfuric acid and hydrogen peroxide. The solutions are mixed together just before use and the reaction is extremely exothermic. Solution temperatures quickly rise to greater than 100 degrees C and generate significant quantities of gasses.
Piranha solutions are incompatible with other acids and organic materials such as alcohols and photoresists. The solutions are very corrosive to eyes, skin, and respiratory tract.
There have been multiple incidents in MIT labs where containers have ruptured due to the use of non-venting caps or mixing spent piranha with incompatibles such as isopropanol. In one instance, the glass bottle exploded and scattered glass throughout the lab. Fortunately, there was no one in the lab at the time of the explosion.
Piranha solutions should never be used in airtight containers. Vented caps should always be used and are available at no charge from the EHS Office. Piranha waste should never be mixed with other chemicals.
Before using this material, consult the detailed Chemical Fact Sheet for Piranha Solutions.
Polychlorinated Biphenyl (PCBs) refer to a class of chemicals consisting of 2 aromatic hydrocarbon rings (phenyls), where each hydrogen position on the carbon ring can be substituted with a chlorine atom. As the number of chlorine atoms on the ring increase so does the stability and thermal resistance properties.
- PCBs have joined a class of regulated materials called PBTs: persistent, bio-accumulative, and toxic chemicals
- PCBs do not degrade readily in the environment (persistent)
- PCBs concentrate in the fatty tissues of organisms, and doses are amplified with each step in the food chain (bio-accumulative)
- PCBs can cause chloracne
Although MIT made a concerted effort to dispose of PCB containing items and electrical equipment in the late 1980s, it is possible that an item pre-dating 1980 may surface when a space is cleaned for a lab move or a renovation. If you are unsure of the date of manufacture of any oil-containing equipment, please contact EHS.
For a comprehensive review of pyrophoric and water reactives materials, please review the SOP (certificate required).
Pyrophoric substances are liquids, solids, or gases that will ignite spontaneously in air at or below 130°F. To receive the pyrophoric classification under GHS a chemical must ignite within 5 minutes in air. However, chemicals that ignite after 5 minutes also pose a significant risk to users and should be handled as pyrophoric.
Water-reactive substances are substances that react with water or moisture to release a gas that is either flammable or a health hazard. When water contacts a water-reactive substance, enough heat may be generated to cause spontaneous combustion or an explosion. The guidelines on this page refer to water-reactive substances that have a risk of igniting on contact with moisture, not those that only release toxic gases.
A laboratory specific SOP is required for use of pyrophoric materials. Contact your DLC’s EHS Coordinator or the EHS Office for assistance.
If your lab plans to, or currently uses, reactive lithium and / or sodium compounds it is recommended that you ensure the appropriate extinguishing agent is available; for example, a Class D extinguisher, sand or a Met-L-X or Lith-X suppression material.
Many factors must be considered when determining what controls are required, including but not limited to the specific pyrophoric chemical(s) being used, type of application, and other hazards. For example, semiconductor research can involve pyrophoric materials that are also highly toxic, requiring additional controls. Contact your EHS Coordinator or the EHS Office for more specific guidance on appropriate controls based on your lab’s research.
Depending on the materials and process, pyrophoric and water-reactive materials should be used in a chemical fume hood (over a spill tray) using techniques that prevent the material from contacting air or in an inert-atmosphere glove box according to the manufacturer’s recommendations.
Before using pyrophoric reagents refer to the Aldrich Technical Bulletins AL-164 and AL-134, which provide detailed instructions on using standard syringe and double-tipped needle transfer techniques to prevent contact with air. Some pyrophoric and water-reactive materials must be handled in a gas-tight syringe to prevent exposure to air.
Flame resistant (FR) lab coats are required when handling pyrophoric substances, including chemicals that release flammable gases that may ignite spontaneously and self-heating chemicals that may catch fire outside of a glove box. FR lab coats should also be worn when working with chemicals that react violently with water or release flammable gas, or when performing potentially vigorous reactions.
Protective eyewear is required when handling pyrophoric and water-reactive materials. Fully enclosed safety goggles or a face shield are preferred, as they offer greater facial protection than safety glasses.
Gloves are required when handling pyrophoric and water-reactive materials. It is recommended that Nomex gloves be worn between two pairs of nitrile gloves for fire protection purposes.
Clothing made from polyester and other synthetic fabrics and loose clothing should not be worn. Always wear long pants and closed toe shoes within the lab. Loose or long hair should be tied back to prevent ignition in the event of a flash fire.
The best way to determine if the substance you are working with is pyrophoric or water reactive is to review the Safety Data Sheet. Safety Data Sheets for all chemicals in a laboratory space must be immediately available. Safety Data Sheets should be updated, reviewed periodically, and used as part of lab specific training.
Common pyrophoric materials include metal hydrides, non metal hydrides, metal halides, alkali metals, metal carbonyls, and metal powders.Note that this list includes examples of pyrophoric and water-reactive materials but is not comprehensive.
Downloadable PDF with hazard details
Many metal powders present special storage and handling concerns when finely divided, including hazards such as air- or water-reactivity or explosive dust generation. Whether a given metal powder exhibits these properties depends on multiple factors, including but not limited to particle size, surface area, moisture level, purity, etc.
Please contact your EHS Coordinator or the EHS Office for assistance when working with small-particle-size metal powders.
Excess pyrophoric chemicals should be treated as hazardous waste. Due to their properties special procedures may be required for waste collection and labs may incur disposal fees based on factors outlined below.
Contact EHS if several bottles are removed from storage at one time, as a fee may be applied depending on the volume. The more toxic and hazardous the chemical and the larger the bottle, the higher the cost tends to be.
Nonreturnable pyrophoric gas cylinders will also incur a cost at the time of disposal. Contact EHS for disposal rates and information on the removal process.
Certain metal powders, such as fine aluminum powder, should be submerged in oil prior to waste collection from the lab. Debris with aluminum powder may be collected with a thin coating of oil and kept separate from other debris waste streams.
Reactive metals, such as lithium, potassium and magnesium, should also be submerged under oil and handled as hazardous waste. Contact EHS for additional guidance.