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Environmental Health & Safety


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  2. Many chemicals or processes in laboratories present physical hazards to staff that need to be recognized and controlled.  Serious injuries or death have occurred when certain chemical reactions release dangerous by-products (toxic gases) or result in a fire or an explosion. The Laboratory Safety Unit recommends the PI/supervisor train personnel for the safe use of these chemicals.  Many of these chemicals should be handled following a written SOP.

    1. Common Chemical Reactive Hazards
    2. Aluminum Chloride (AlCl3): Dangerous material if moisture is present.  Decomposition can produce hydrogen chloride gas (HCl) and build up pressure in a container.  When opening a bottle of aluminum chloride, always cover the top with a heavy towel.

      Ammonia: Reacts with iodine to form nitrogen tri-iodide (a contact explosive).  Reacts with hypochlorites to produce chlorine.  Do not mix with bleach.  Ammonia mixed with organic halides can react violently when heated under pressure.  Ammonia gas needs to be stored and used in an operational ventilated gas cabinet with the gas line extending into an operational chemical fume hood.  Concentrated ammonium hydroxide solutions need to be used in an operational chemical fume hood.

      Aqua Regia:  This mixture of nitric acid and hydrochloric acid is sometimes used to dissolve nanomaterials, noble metals or as a gas cleaner.  This agent should be used only when other agents fail to dissolve the materials of concern or clean the intended glass item(s).  Storage of this agent in a closed container can cause the container to rupture/fail.  When the nitric acid in Aqua Regia begins to reduce, it evolves toxic nitrogen dioxide gas.  Therefore, all uses of Aqua Regia need to be carried out in an operational chemical fume hood.

      Benzoyl Peroxide (C6H5CO2)2: Easily ignited and sensitive to shock.  Spontaneously decomposes at temperatures above 50C.  Hazard can be minimized by the addition of 20% (V/V) water.

      Carbon Disulfide (CS2): Highly toxic and highly flammable.  If open to the atmosphere, its vapors can be ignited by heat exceeding 80C (from a hot plate, "hot" light bulb, steam bath, etc.).  Handle this agent in an operating chemical fume hood.

      Catalysts (Palladium or Platinum with carbon, Platinum oxide, Raney nickel, etc.): When catalysts are used to generate certain catalytic hydrogenation reactions, such catalysts exposed to the air will ignite spontaneously.  Keep such catalysts covered with water.  When recovering a catalyst, place the material into a water bath immediately after completion of any filtration.

      Chlorine (Cl2):  Reacts violently with hydrogen or with hydrocarbons in the presence of sunlight.  Chlorine needs to be stored and used in an operational ventilated gas cabinet with the gas line extending into an operational chemical fume hood.

      Diazomethane (CH2N2) and Many Diazo Compounds: These agents are very toxic and the pure form of the compounds explode readily.  Solutions in ether are "safer". Solutions can be rendered harmless by the drop-wise addition of acetic acid.

      Diethylzinc (C2H5)2Zn: Because this agent is such a violent pyrophoric (air-reactive), water-reactive, and light-sensitive, it is normally sold in a mixture of toluene, hexane, or other organic solvent.  Do not attempt to concentrate (keep the concentration below 1.1 molar) this agent by allowing the solvent to evaporate.  Fires of this agent require the use of a Class D (dry powder) fire extinguisher or the use of soda ash or lime.

      Dimethyl Sulfoxide (CH3)2SO:  Decomposed violently in the presence of halogen compounds.  Explosions have been reported when this chemical is mixed with metal halides.  Because this chemical readily penetrates the skin, it can carry any other chemical present through the skin as well.

      Dinitrophenols (NO2)2C6H3OH:  These compounds are sensitive to friction, shock and light and should never be allowed to dry.  2,4-dinitrophenol reacts with alkalis and ammonia to form explosive salts.  Because dinitrophenols are explosive, they are subject to ATF regulations.  EH&S must be contacted for the possession of dinitrophenol materials to ensure proper storage and quantity storage.  Decomposition of these compounds can produce nitrogen oxides that can cause pulmonary edema and/or genetic changes.

      Dry Ice (CO2, solid carbon dioxide):  Dry ice can produce severe skin burns.  Dry ice will sublimate at room temperature to carbon dioxide gas.  Do not store in walk-in cold rooms because sufficient gas can be generated to cause an oxygen-deficient atmosphere.  Do not store in ultra-low freezers because the loss of power can result in the release of sufficient carbon dioxide gas to cause a pressure buildup that could result in a mechanical explosion.  For additional information, consult

      Fulminic Acid (HCNO):  Compounds containing the fulminate ion are highly unstable and are friction-sensitive explosive substances.  These compounds are subject to ATF regulations.  The Laboratory Safety Unit must be contacted for the possession of mercury fulminate, silver fulminate, and fulminic acid to ensure proper storage and quantity storage.

      Grignard Reagents (R-Mg-X): These alkyl- and aryl- magnesium halides are highly reactive with oxygen and carbonyls compounds.  Exposure to moist air can result in spontaneous ignition.  Handle Grignard reagents under inert atmospheres (argon or nitrogen) or in solvents such as ethyl ether or tetrahydrofuran.

      Halogenated Compounds:  Violent explosions can result when halogenated compounds (chloroform, methylene chloride, carbon tetrahydrofuran) are dried with sodium, potassium or other active metals.

      Hydrofluoric Acid HF:  Hydrofluoric acid exposures can result in severe, deeply penetrating burns to the eyes, lungs and skin.  The concentrated form of these compounds can cause a burning sensation. Exposure to dilute solutions may not result in a burn sensation for several hours.  This time delay between exposure recognition and treatment can lead to burns that are difficult to treat or other systemic complications.  NEVER store hydrofluoric acid or its solutions in glass containers (always use polyethylene containers).  Check containers annually and dispose of old container of the acid upon first indication of aging (hairline fractures in the plastic).

      Hydrogen Peroxide (H2O2):  Solutions of 30% or greater of hydrogen peroxide can cause severe skin burns.  30% hydrogen peroxide can decompose violently if mixed or become contaminated with iron, copper, chromium or their metal salts.

      Liquid Nitrogen:  Approximately one liter of liquid nitrogen will expand to roughly 700 liters.  Because of the thermal expansion, good general ventilation is mandatory when handling cryogenic materials to ensure oxygen-deficient atmosphere is not generated. Contact with skin tissue can result in severe burns in a very short period of time.  Personnel must wear a face shield and thermal gloves.

      Lithium Aluminum Hydride (LiALH4):  Do not use this chemical to dry methyl ethers or tetrahydrofurans or a fire may occur. An explosion can occur if mixed with carbon dioxide.  Therefore, do not use a carbon dioxide fire extinguisher to put out a lithium aluminum hydride fire.  Rather, use sand or a Class D fire extinguisher.

      Nitric Acid (NHO3):  Because nitric acid is such a strong oxidizer, do not store nitric acid with organic acids (i.e., acetic acid or formic acid).  Nitric acid will react explosively with organic substances (for example, acetic anhydride, acetone, acetonitrile, alcohols, benzene, methylene chloride, etc.).  Nitric acid will react violently with bases, reducing agents alkali metals, copper, phosphorous, and ammonia.  Nitric acid can react on wood surfaces causing the wood to char.

      Nitrocellulose (C6H7O11N3)4: Dry nitrocellulose (Guncotton, Parlodion, Pyroxylin) is explosive when subject to sudden shock or when heated.  This agent needs to be maintained in moistened state.

      Nitroglycerin C5H3(NO3)3:Nitroglycerin in the dry state is a high explosive. Any nitroglycerin that may be present in a lab must be kept moist, usually by the addition of alcohol.  This agent is subject to ATF regulations.  The Laboratory Safety Unit is to be notified for the possession of this agent.

      Oxygen:  Oil or grease on either fittings or threads of an oxygen tank or a regulator can result in an explosion should the oxygen be turned on from an oxygen tank.  Personnel are to inspect the threads of an oxygen tank and the regulator connection before mounting the regulator onto the tank.  To minimize potential grease/oils on these surfaces, personnel are to wear disposable gloves.  Do not use a soap solution to check for a gas leak from any connections.

      Ozone: Ozone may be generated in a lab when certain ultraviolet sources are used.  Such sources should be vented into a local exhaust system (fume hood, slot hood, canopy hood).

      Perchlorates:  Perchlorates when in contact with metals can result in an explosion hazard. Perchloric acid digestions must be carried out in a special perchlorate hood, equipped with wash down capabilities.  Frequent washing of these hoods is needed to minimize the potential build up of perchlorates in the duct.  Heated (boiling) 70% perchloric acid in the presence of organic material will readily oxidize the organic material and could lead to an explosion.  Do not use perchlorates as a drying agent or concentrate perchloric acid to concentrations greater than 70%.

      Permanganates:  Permanganates in the presence of sulfuric acid become explosive.  Always keep permanganates separate from sulfuric acid in storage and in use.

      Peroxides:  Explosive mixtures are generated when inorganic peroxides come into contact with or are mixed with combustible materials, barium, sodium, or potassium.

      Phosphorus:  Explosive mixtures are generated when either red or white phosphorus come into contact with or are mixed with oxidizing agents.  Because white (yellow) phosphorus is pyrophoric, it needs to be stored under water.  Phosphine, a highly toxic gas, is generated if phosphorus contacts or mixes with aqueous hydroxides.

      Phosphorus trichloride PCL3: Phosphine, a highly toxic gas, can be generated if phosphorus trichloride reacts with water.  Eye protection, a face shield and gloves must be worn when opening containers of phosphorus trichloride.

      Picric Acid (dinitrophenol) and related compounds (dipicrylamine):  These compounds form explosive compounds when they come into contact with or are mixed with combustible materials.  These compounds are relatively stable provided they are saturated with water.  Should they dry (less than 10% water by weight), they are high explosive and the containers must not be touched/disturbed except by a bomb squad.  If these materials are stored in metal containers, highly explosive metal picric salts are generated.

      Piranha Solution:  Piranha solutions are prepared by mixing sulfuric acid and hydrogen peroxide and when made, can generate heat over 100C.  It is used to remove organic material from surfaces.  Make only what is needed for immediate use and discard (as hazardous waste) any remaining and the used solution.  NEVER STORE UNUSED SOLUTION.

      Potassium:  Potassium ignites quickly on exposure to humid air.  Handle under the surface of mineral oil or kerosene (like sodium).  Destroy any scraps of potassium by reacting them with n-butanol.  Use a sand or Class D fire extinguisher on alkali fires (do NOT use a CO2 extinguisher).

      Sodium:  Sodium reacts violently with water to form hydrogen.  The heat that is released can cause ignition.  Keep sodium stored under kerosene, toluene, or mineral oil.  Destroy any scraps of sodium by reacting them with n-butanol.  Use a sand or Class D fire extinguisher on alkali fires (do NOT use a CO2 extinguisher).

      Sodium Azide NaN3:  Sodium azide, even trace quantities, reacts with copper and lead to form explosive copper or lead azide.  NEVER drain dispose solutions containing azide compounds.  Rather, dispose of these solutions as hazardous waste.  Sodium azide is highly toxic.  Sodium azide can decompose explosively due to heat, shock, or friction.  Sodium azide should never be mixed with nitric or sulfuric acid.

      Tertiary Butyl Lithium (CH3)3CLi:  Tert-butyl lithium is the most reactive of commercially available organolithium reagents.  It is a pyrophoric chemical – it will spontaneously catch on fire when exposed to air.  A dry chemical fire extinguisher is needed in the event of a t-butly lithium fire.  A written SOP must be followed for handling this agent.

      Trichloroethylene Cl2CCHCl: Trichloroethylene is toxic.  NEVER use this agent as a degreasing solvent.  Mixture of trichloroethylene hydroxide (sodium or potassium) can spontaneously ignite in the air.

    3. Physical Hazards in Laboratories
    4. Autoclaves:  Steam sterilization of materials is a dependable procedure for the destruction of microbial life. The hot, pressurized steam that autoclaves use presents a serious burn hazard to users.  These hazards and the precautions for the safe use of an autoclave can be found at

      Centrifuges:  Although centrifuges are typically used for the separation of biological materials, a number of chemicals are used with centrifuges.  The use of cesium chloride gradients can present a hazard to the user should the load not be balanced or the rotors are used above the recommended speed for the density of the materials.

      Cold Rooms:  Because cold rooms do NOT have ventilation, personnel need to limit their use to about 2 hours per day to minimize the buildup of carbon dioxide.  Compressed gases and solvents are not to be used in cold rooms.  For additional information consult

      Electrical Hazards:  Electrically powered lab equipment pose a significant hazard to personnel.  Even currents of 6 milliamps can be painful and ventricular fibrillation can occur at 1000 milliamps. Damaged electric cords/appliance must be taken out of service for repair by an electrician.  Check outlets within 6’ of a sink to verify outlets are GRI protected.

      Glassware:  Check all glassware before use for cracks/damage.  If damaged, discard immediately into a glass waste container.

      Hot Surfaces:  Continuously operating hot plates pose a burn hazard to personnel.  Post a hazard sign to warn personnel of the hot surface.

      Lasers:  In addition to the intense coherent, collimated, and monochromatic light lasers generate, lasers can also present eye/skin damage, release particulates into the air, create potential exposures to carcinogens (laser dyes, present intense noise, and can present electrical shock hazards to personnel. For additional information on lasers, consult

      Liquid Nitrogen Cooled Traps:  Should these traps become open to the atmosphere, atmospheric oxygen can condense within the trap resulting in the glass to shatter.  If the trap contains organic materials, an explosion could occur.

      Magnetic Fields:  Intense magnetic fields can present a hazard to personnel with implanted medical devices.  Signage will indicate locations that have a static magnetic field of 1.5 Tesla or a spatial gradient field of 1000 Gauss/cm.

      Parr Bombs:  Handle all bomb calorimeters as high-stress equipment.  Such handling includes working with the unit while protected by a bench shield and while wearing eye protection

      Pinch Points:  Belt driven equipment, such as vacuum pimps, must have a guard in place to prevent fingers/clothes from becoming entangled in the moving parts.

      Tubing:  Tubing (Tygon and rubber) provide some flexibility when used.  When tubing is used for hazardous gases (gas anesthesia or natural gas) check all connections for possible leakage.

      UV Light:  Exposure to UV light can result in adverse health effects that include erythema (sunburn), photokeratitis (a feeling of sand in the eyes), skin cancer, melanoma, cataracts, and retinal burns.  UV lights may be found in germicidal lamps, biological safety cabinets, and transilluminators.  See the hazards and precautions as listed in

      Vacuum Distillation Residues: Explosions can occur when a vacuum distillation still is vented to the air before the material has cooled.  Always vent stills with nitrogen, allow the equipment to cool to room temperature, before venting.

QUESTIONS or COMMENTS? Contact EH&S at (585) 275-3241 or e-mail EH&S Questions.

This page last updated 7/30/2015. Disclaimer.