Environmental Health and Safety

Laboratory Safety Manual - 2011

IV. Basic Guidelines for Working with Hazardous Materials

  1. General Rules
  2. Working with Allergens
  3. Working with Embryotoxins
  4. Working with Chemicals of Moderate Chronic or High Acute Toxicity
  5. Working with Substances of High Chronic Toxicity

1. General Rules

  1. Laboratory Protocol
    Everyone in the lab is responsible for their own safety and the safety of others.

    Before starting any work in the lab, personnel should be familiar with the procedures and equipment being used.  Lab personnel should be aware of the chemical hazards before working with them.  Personnel who are unfamiliar with the hazardous material or a new procedure should consult their supervisor.

    MSDS information available here: http://www.utexas.edu/safety/ehs/msds/

    The following guidelines are recommendations for working safely in a lab:

    Personal Safety Practices
  • Lab coats, gloves and safety glasses should be worn as appropriate in all laboratories.   
  • Do not wear shorts, sandals, or open-toed shoes in lab.
  • Minors or personal pets are not permitted in laboratories.
  • Do not mouth pipette.
  • Secure any dangling jewelry, restrain loose clothing, and tie back long hair that might get caught in equipment before starting work.
  • Food and drink should not be consumed in the lab.
  • Do not store food and drinks in laboratory refrigerators.

    photo of refrigerator sign
    Refrigerator sign

  • Avoid working alone in the lab. If you must work alone, make someone (such as a supervisor) aware of your location.
  • Wash your hands frequently throughout the day and before leaving the lab.
  • Do not wear lab coats, gloves, or other personal protective clothing outside of lab areas. This clothing may have become contaminated and you could spread the contamination.
  • Cell phones and use of music headphones should be avoided while working in the lab. They can be distracting and thereby increase the potential for an accident to occur. They can also become contaminated if handled while working with hazardous materials.

    photo of person talking on a cell phone in the lab
    Cell phones should not be used while working in the lab

Housekeeping and Decontamination

  • Work areas must be kept clean and free of unnecessary chemicals. Clean the work area throughout the day and before leaving the lab for the day.
  • If necessary, clean equipment after use to avoid the possibility of exposing the next person who uses it.
  • Keep all aisles and walkways in the lab clear to provide a safe walking surface and an unobstructed exit. Do not block doors.
  • Do not block access to emergency equipment (i.e. fire extinguishers, eyewashes, etc.), emergency shut-offs, and utility controls (i.e. electrical panels).

    photo of cluttered workspace
    Cluttered workspace. Emergency eyewash obstructed.
    photo of blocked fire extinguisher
    Blocked fire extinguisher

  1. Accidents and Spills
    See the Emergency Procedures section for detailed procedures.  Do not clean up spills unless trained to do so.

    Supplies for cleaning up minor spills should be readily available.  In case of release, promptly clean up spills using appropriate personal protective equipment (PPE).

    Spill Response Equipment
    Supplies for a chemical spill should include:
  • An inert absorbent such as kitty litter or vermiculite or a 50/50 mixture of the two or a commercial absorbent
  • A plastic (non-sparking) scoop, plastic bags for the spilled material
  • Chemical resistant gloves
  • Goggles
  • Sodium bicarbonate to neutralize acids.

    photo of items in a spill kit
    Items that should be included in a spill kit

Note: All spent spill clean-up materials should be disposed of in the same manner as the spilled chemical or biological material.  Spill clean-up supplies should be checked and re-stocked as necessary.  Dispose of clean-up material through the EHS waste disposal program.

  1. Steps to Prevent Routine Exposure
  • Develop and encourage safe habits
  • Avoid unnecessary exposure to chemicals by any route
  • Do not smell or taste chemicals
  • Vent any apparatus which may discharge toxic chemicals (e.g., vacuum pumps, distillation columns) into local exhaust devices such as fume hoods
  • Inspect gloves and test glove boxes before use
  • Do not allow release of toxic substances in cold rooms or warm rooms, since these have contained, re-circulated air
  1. Equipment and Glassware
    EHS recommends the following guidelines for the use and care of glassware and other laboratory equipment:

Glassware and Glass Bottles

photo of bottle carrier
Bottle carrier
  • Inspect all glassware before use. Discard any broken, cracked, or chipped glassware.
  • Tape or shield glass vacuum vessels to prevent flying glass in the case of an implosion. Also, tape or shield glass vacuum desiccators.
  • Transport all glass chemical containers in rubber or polyethylene bottle carriers when leaving one lab area to enter another. Use a cart if transporting more than two bottles. 
  • Fire-polish all cut glass tubing and rods before use.
  • Practice the following when inserting glass tubes or rods into stoppers:
    • Be certain that the diameter of the tube is compatible with the diameter of the stopper.
    • Fire-polish the end of the glass tube.
    • Lubricate the glass with water or glycerol.
    • Wear heavy gloves and hold the glass not more than two inches from the end to be inserted.
    • Insert the glass carefully with a twisting motion.
    • Remove stuck tubes by slitting the stopper with a sharp knife.

Assembly of Laboratory Apparatus

  • Firmly clamp apparatus and set up away from the edge of the lab bench.
  • Only use equipment that is free from cracks, chips, or other defects.
  • If possible, place a pan under a reaction vessel or other container to contain liquid if the glassware breaks.
  • Do not allow burners or any other ignition sources nearby when working with
    flammable liquids.
  • Lubricate glass stopcocks.
  • Properly support and secure condensers and water hoses with clamps and wires.
    Be sure to direct the water hoses so that any drips that come off the hoses do
    not splash down onto any electrical wires.
  • Position apparatus that is attached to a ring stand with the center of gravity over the base and not to one side.
  • Assemble the apparatus so that burners or baths can be removed quickly.
  • Use an appropriate vapor trap and confine the setup to a fume hood if there is a
    possibility of hazardous vapors.
  • Put the setup in a fume hood whenever conducting a reaction that could result in an implosion or explosion. Keep the sash pulled down. If it is not possible to use a fume hood, use a standing shield that is stabilized and secured.

Centrifuges

  • Securely anchor tabletop centrifuges and place in a location where the vibration will not cause lab equipment to fall off the bench top.
  • Keep the centrifuge lid closed while operating and do not leave the centrifuge until you are certain it is running safely without vibration.
  • If the centrifuge starts vibrating, stop and check the load balances.
  • Regularly clean rotors and buckets with a non-corrosive cleaning solution.
  • Use sealed safety cups while centrifuging hazardous materials.

    photo of a centrifuge
    Sealed safety cups being used in a centrifuge

untraviolet light symbol

Ultraviolet Lamps

  • Wear ultraviolet absorbing protective safety glasses while working with ultraviolet light.
  • Protect your skin from potential burns due to ultraviolet light.
  • Shield any project in which ultraviolet light is used to prevent escape of the direct beam or scattered radiation.

laser symbol

Lasers

  • Always wear goggles that protect against the specific wavelength of the laser.
  • Never look directly at the beam.
  • Do not allow any reflective materials in or along the path of the beam.
  • Post warning signs in all laser areas. If required, use a flashing light at the lab entrance to indicate when a laser is in use.

    photo of laser warning sign
    Laser warning sign
    photo of laser warning light
    Laser warning light

  • Consult the EHS Laser Safety Manual for more information or contact the Laser Safety Officer at EHS.

Separatory Funnels

  • Use extreme caution if the temperature of the materials is elevated.
  • When a volatile solvent is used, swirl the unstoppered separatory funnel first to
    allow some solvent to vaporize and to release pressure.
  • Close the funnel and invert it with the stopper held in place, then immediately open the stopcock to release pressure.
  • Do not vent the separatory funnel near a flame or any other ignition source.
  • Do not point the funnel at a co-worker.   Be aware of nearby co-workers.
  • Vent the separatory funnel into a fume hood.
  • Close the stopcock, swirl the funnel, then immediately open the stopcock with the funnel in an inverted position to vent the vapors again.

Cryogens, Cooling Baths and Cold Traps

  • Always use caution when working with cryogenic coolants.
  • Use temperature resistant gloves and a face shield while slowly immersing an
    object to be cooled.
  • Do not pour cold liquid onto the edge of a glass Dewar flask when filling because
    the flask may break and implode. 
  • Never lower your head into a dry ice chest; no oxygen is present.
  • Wear temperature resistant gloves while handling dry ice. If no protection is used, severe burns can result.
photo of bottle carrier
Vacuum pump

Vacuum Pumps

Mechanical vacuum pumps used in laboratories pose many hazards. There are mechanical hazards associated with the moving parts. There are chemical hazards of contaminating the pump oil with volatile substances and subsequently releasing them into the lab. There are also fire hazards when pumps malfunction or overheat and ignite nearby flammable or combustible materials.

Follow these guidelines for safe pump operation:

Physical (injuries/fires)

  • Ensure that pumps have belt guards in place during operation to prevent hands or loose clothing from getting caught in the belt pulley.
  • Ensure that electrical cords and switches are free from defects.
  • Do not place pumps in an enclosed, unventilated cabinet allowing heat and exhaust to build up.
  • Do not operate pumps near containers of flammable chemicals, flammable chemical wastes, or combustible materials such as paper or cardboard.
  • Use correct vacuum tubing (thick walls) not thin Tygon-type hoses.
  • Replace old tubing; crumbly tubing can degrade performance.
  • Use the shortest length of tubing that reaches where needed.

Chemical

  • Do not use solvents which might damage the pump.
  • Always close the valve between the vacuum vessel and the pump before shutting off the pump to avoid sucking vacuum oil into the system.
  • Place a pan under pumps to catch oil drips.
  • Check oil levels and change oil when necessary. Replace and properly dispose of vacuum pump oil that is contaminated with condensate. Used pump oil must be disposed as hazardous waste.
  • With oil rotary pumps many vapors condense in the pump oil. Solvents in the oil degrade its performance (and eventually ruin the pump), create a chemical hazard when the oil is changed, and are emitted in an oil mist vented from the system. Other vapors pass directly into the exhaust stream. To avoid these problems:
    • Trap evaporated materials with a cold trap before they reach the pump. Depending on the material that is to be trapped, this can be a filtration flask either at room temperature or placed in an ice bath. For more volatile solvents more sophisticated options exist (e.g. dry ice trap).
    • Vent the pump exhaust properly.

Personnel

  • Conduct all vacuum operations behind a table shield or in a fume hood and always wear safety glasses, lab coat, and gloves.
  • Keep a record for each pump to record oil change dates and to keep track of the maintenance schedule.

Electrical

  • Examine all electrical cords periodically for signs of wear and damage. If damaged electrical cords are discovered, unplug the equipment and have it repaired.
  • Properly ground all electrical equipment.
  • If sparks are noticed while plugging or unplugging equipment or if the cord feels
    hot, do not use the equipment until it can be serviced by an electrician.
  • Do not run electrical cords along the floor where they will be a tripping hazard and be subject to wear. If a cord must be run along the floor, protect it with a cord cover.
  • Do not run electrical cords above the ceiling. The cord must be visible at all times to ensure it is in good condition.
  • Do not plug too many items into a single outlet. Cords that enable you to plug more than one item in at a time should not be used.
  • Multi-plug strips can be used if they are protected with a circuit breaker.  Do not overuse or daisy-chain in a series.

    photo of overused multi-plug strip
    Overused multi-plug strip
    photo of daisy-chained electrical cords
    Electrical cords daisy-chained

  • Do not use extension cords for permanent wiring. If you must use extension cords
    throughout the lab, then it is time to have additional outlets installed.
  1. Personal Protective Equipment (PPE)
    The most important thing to remember about protective clothing is that it only protects you if you wear it. The lab supervisor must ensure that appropriate personal protective equipment is worn by all persons, including visitors, in areas where chemicals are stored or handled.

    Material Safety Data Sheets or other references should be consulted for information on the type of protective clothing required for the particular work you are performing.

    In general, when working in an area with hazardous materials, your skin should be covered from shoulders to toes.

Protective Eyewear

eye protection required symbol
  • Goggles provide the best protection against chemical splashes, vapors, dusts, and mists.
  • Goggles that have indirect vents or are non-vented provide the most protection, and an anti-fog agent can be applied.
  • Standard safety glasses provide protection against impact.
  • Remember, prescription glasses do not provide adequate protection in a laboratory setting. Prescription safety glasses can be purchased from most opticians.
  • Alternatively, safety glasses and goggles designed to fit over prescription glasses are available through commercial vendors.

Face shields

face shield required symbol
  • Face shields can protect against impact, dust, particulates, and splashes to the face, eyes, and throat. However, always wear protective eyewear such as goggles underneath a face shield. Chemical vapors and splashes can still travel under and around a face shield.
  • If scratches or cracks are noticed in the face shield, replace the window.

Protective Gloves

gloves required symbol
  • Any glove can be permeated by chemicals. The rate at which this occurs depends on the composition of the glove, the chemicals present and their concentration, and the exposure time to the glove. If you are not certain which type of glove provides you with the protection you need, contact the manufacturer and ask for specifics on that glove.
  • Chemical Compatibility Guides
  • If direct chemical contact occurs, replace gloves regularly throughout the day. Wash hands regularly and remove gloves before answering the telephone or opening doors to prevent the spread of contamination.
  • Check gloves for tears, holes and cracks.
  • Butyl, neoprene, and nitrile gloves are resistant to most chemicals, e.g., alcohols, aldehydes, ketones, most inorganic acids, and most caustics.
  • Disposable latex and vinyl gloves protect against some chemicals, most aqueous solutions, and microorganisms and reduce risk of product contamination.
  • Leather and some knit gloves will protect against cuts, abrasions, and scratches, but not against chemicals.
  • Temperature-resistant gloves protect against cryogenic liquids, flames, and high temperatures such as autoclaves.

Note: Latex gloves should not be worn if a person has or suspects a latex allergy.

Lab Coats and Aprons

lab coat required symbol  apron required symbol
  • The primary purpose of a lab coat is to protect against splashes and spills. A lab coat should be nonflammable, where necessary, and should be easily removed.  Other types of lab coats such as flame resistant coats are available.
  • Lab coats should be buttoned when in use.
  • Rubber coated aprons can be worn to protect against chemical splashes and may be worn over a lab coat for additional protection.

Shoes

closed toed shoes required symbol
  • Shoes that fully cover the feet should always be worn in a lab. If work is going to be performed that includes moving large and heavy objects, steel-toed shoes should be worn.
respirator required symbol  respiratory protectin required symbol

Respirators
Contact EHS if you are conducting research that necessitates the need for a respirator.  EHS will evaluate whether there is a need for a respirator and what type of respirator is needed.  Occupational Health will conduct fit-testing and a medical respiratory protection evaluation.


  1. Unattended Operations
    Leave lights on, place an appropriate sign on the door, and provide for containment of toxic substances in the event of failure of a utility service (such as cooling water) to an unattended operation.
  2. Use of Fume Hoods
    Use a fume hood for all procedures that might result in the release of hazardous chemical vapors or dust.
  • Confirm that the hood is working before use by holding a Kimwipe®, or other lightweight paper, up to the opening of the hood.
  • The paper should be pulled inward.
  • Leave the hood "on" when it is not in active use if toxic substances are stored inside or if it is uncertain whether adequate general laboratory ventilation will be maintained when it is "off."

Proper Use of Fume Hoods

  • Equipment and other materials should be placed at least six inches behind the sash, preferably in the middle of the hood. This will reduce the exposure of personnel to chemical vapors that may escape into the lab due to air turbulence.
  • When the hood is not in use, pull the sash all the way down. While personnel are working at the hood, pull down the sash as far as is practical. The sash is constructed of safety glass to protect users against fire, splashes, and explosions.

    photo of the fume hood with sash down as far as possible
    Work with the fume hood sash down as far as practical
    photo of improper use of the fume hood
    Improper use of the fume hood

  • Fume hood sash should be at or below 18 inches.
  • Do not keep loose papers, paper towels, or tissues (e.g., Kimwipes®) in the hood. These materials can be drawn into the blower and adversely affect the performance of the hood.
  • Do not use a fume hood as a storage cabinet for chemicals.

    photo of chemicals and othe items in the fume hood
    Do not store chemicals or other items in the fume hood

  • Excessive storage of chemicals and other items will disrupt the designed airflow in the hood. In particular, do not store chemicals against the baffle at the back of the hood, because this will interfere with the laminar airflow across the hood.
  • If large equipment must be kept in a fume hood, raise it 1.5 inches off the work surface to allow air to flow underneath. This dramatically reduces the turbulence within the hood and increases its efficiency.
  • Do not place objects directly in front of a fume hood (such as refrigerators or lab coats hanging on the manual controls) as this can disrupt the airflow and draw contaminants out of the hood.
  • Keep in mind that modifications made to a fume hood system, e.g., adding a snorkel, can render the entire system ineffective. Modifications should not be done without proper authorization.
  • Minimize the amount of foot traffic immediately in front of a hood. Walking past hoods causes turbulence that can draw contaminants out of the hood and into the room.
  1. Storage of Chemicals in the Lab
    Refer to the section on laboratory chemical storage in Chapter C.1.

2. Working with Allergens

A wide variety of substances can illicit skin and lung hypersensitivity. Examples include common substances such as; diazomethane, chromium, nickel, bichromates, formaldehyde, isocyanates, and certain phenols. Because of this variety and the varying response of individuals, suitable gloves should be used whenever there is potential for contact with chemicals that may cause skin irritation.

3. Working with Embryotoxins

Embryotoxins are substances that cause adverse effects on the developing fetus in pregnant women. These effects may include embryolethality (death of the fertilized egg, the embryo, or the fetus), malformations (teratogenic effects), retarded growth, and postnatal function deficits.
A few substances have been demonstrated to be embryotoxic in humans.

These include:

Benzene
Heavy Metals
Carbon Tetrachloride
Chloroform

Azo dyes
Propylene glycol
Xylene
Formaldehyde

Nitrous oxide
Toluene

Many substances, some as common as sodium chloride, have been shown to be embryotoxic to animals at some exposure level, but usually this is at a considerably higher level than is encountered in the course of normal laboratory work. However, some substances do require special controls due to embryotoxic properties. One common example is formamide: women of childbearing potential should handle this substance only in a hood and should take precautions to avoid skin contact with the liquid because of the ease with which it passes through the skin.

Because the period of greatest susceptibility to embryotoxins is the first 8-12 weeks of pregnancy, which includes a period when a woman may not know that she is pregnant; women of childbearing potential should take care to avoid skin contact with all chemicals. The following procedures are recommended to be followed routinely by women of childbearing potential in working with chemicals requiring special control because of embryotoxic properties:

4. Working with Chemicals of Moderate Chronic or High Acute Toxicity

Before beginning a laboratory operation, each worker is strongly advised to learn about the substances to be used. The precautions and procedures described in this section should be followed if any of the substances used in significant quantities are known to be moderately or highly toxic (if any of the substances used are known to be highly toxic, it is recommended that two people be present in the area at all times).

These procedures should also be followed if the toxicological properties of any of the substances used or prepared are unknown. If any of the substances to be used or prepared are known to have high, chronic toxicity (e.g., compounds of heavy metals and other potent carcinogens), then the directions and procedures described below should be supplemented with additional precautions to aid in containing and ultimately destroying the substances having high chronic toxicity. Some examples of potent carcinogens (substances known to have high chronic toxicity), along with their corresponding chemical class, are:

Alkylating Agents:
α -Halo Ethers
   Bis(Chloromethyl) Ether
   Methyl Chloromethyl Ether

Aziridines
   Ethylene Imine
   2-Methylaziridine

Diazo, Azo, and Azoxy Compounds
   4-Dimethylaminoazobenzene

Electrophilic Alkenes and Alkynes
   Acrylonitrile
   Acrolein
   Ethyl Acrylate

Epoxides
   Ethylene Oxide
   Diepoxybutane
   Epichlorohydrin
   Propylene Oxide
   Styrene Oxide

Sulfonates
   Diethyl Sulfate
   Dimethyl Sulfate
   Ethyl Methanesulfonate
   Methyl Methanesulfonate
   Methyl Trifluoromethanesulfonate
   1,3-Propanesultone
   1,4-Butanedioldimethanesulfonate

Acylating Agents:
   β –Butyrolactone
   β -Propiolactone
   Dimethylcarbamoyl Chloride

Aromatic Amines:
   4-Aminobiphenyl
   Aniline
   o-Anisidine
   Benzidine
   o-Toluidine

Organohalogen Compounds:
   1,2-Dibromo-3-Chloropropane
   Bis(2-Chloroethyl) Sulfide
   Vinyl Chloride
   Chloroform
   Methyl Iodide
   2,4,6-Trichlorophenol
   Carbon Tetrachloride
   Hexachlorobenzene
   1,4-Dichlorobenzene

Natural Products:
   Adriamycin
   Aflatoxins
   Bleomycin
   Progesterone
   Reserpine
   Safrole

Inorganic Compounds:
   Cisplatin

The overall objective of the procedures outlined in this section is to minimize exposure of the laboratory worker to toxic substances by taking all reasonable precautions. Thus, the general precautions outlined in Section D.1 should normally be followed whenever a toxic substance is being transferred from one container to another or is being subjected to some chemical or physical manipulation. The following precautions should always be followed:

  1. Protect the hands and forearms by wearing either gloves and a laboratory coat or suitable long gloves to avoid contact of the toxic material with the skin.
  2. Procedures involving volatile toxic substances and those involving solid or liquid toxic substances that may result in the generation of aerosols should be conducted in a fume hood or other suitable containment device.
  3. After working with toxic materials, wash the hands and arms immediately. Never eat, drink, chew gum or tobacco, apply cosmetics or contact lenses, take medicine, or store foods in areas where toxic substances are being used.

These standard precautions will provide laboratory workers with good protection from most toxic substances. In addition, records that include amounts of material used and names of workers involved should be kept as part of the laboratory notebook record of the project. To minimize hazards from accidental breakage of apparatus or spills of toxic substances in the fume hood, containers of such substances should be stored in pans or trays made of polyethylene or other chemically resistant material and apparatus should be mounted above trays of the same type of material.

Alternatively, the working surface of the hood can be fitted with a removable liner of adsorbent plastic-backed paper. These materials will contain spilled toxic substances in a pan, tray, or absorbent liner and greatly simplifies subsequent cleanup and disposal. Any material that comes in contact with toxic substances should be disposed of as a toxic substance. Vapors that are discharged from the apparatus should be trapped or condensed to avoid adding substantial amounts of toxic vapor to the hood exhaust air. Areas where toxic substances are being used and stored must have restricted access, and warning signs must be posted if a special toxicity hazard exists.

The general waste disposal procedures described in the EHS Waste Disposal manual must be followed for these types of chemicals. In general, the waste materials and solvents containing toxic substances must be stored in closed, impervious containers so that personnel handling the containers will not be exposed to their contents.

The laboratory worker must be prepared for potential accidents or spills involving toxic substances. Lab workers must be trained in handling toxic materials and spill clean-up before beginning work with toxic substances.

If a toxic substance contacts the skin, the area should be washed with water. If there is a major spill outside of the hood, the room or appropriate area should be evacuated and necessary measures should be taken to prevent exposure of other workers. Spills must be cleaned by personnel wearing suitable personal protective apparel. If a spill of a toxic material occurs outside the hood, an air-supplied full-face respirator may be needed. Immediately contact EHS for assistance.

In addition to the precautions described in this section, researchers should develop written standard operating procedures intended to establish a concise, step-by-step method for carrying out routine laboratory operations with the substance in question and train lab personnel on these procedures.

5. Working with Substances of High Chronic Toxicity

highly toxic symbol

All of the procedures and precautions described in the previous section should be followed when working with substances known to have high chronic toxicity. In addition, when such substances are used in quantities exceeding a few milligrams to a few grams, depending on the hazards posed by the particular substance, the additional precautions described in this section should be followed. Each laboratory worker’s plan for project work and for disposing of waste materials must be approved by the laboratory supervisor.

Consultation with the departmental Lab Safety Coordinator or EHS is recommended to ensure that the toxic material is effectively contained during the project and that waste materials are disposed of in a safe manner. Substances in this high chronic toxicity category include certain heavy metal compounds (e.g., dimethylmercury and nickel carbonyl) and compounds normally classified as select carcinogens. Examples of compounds normally classified as select carcinogens include the following:

2-acetylaminofluorene
aflatoxin B1
benzo[a]pyrene
bis(chloromethyl) ether
7,12-dimethylbenz[a]anthracene
dimethylcarbamoyl chloride

hexamethylphosphoramide
3-methylcholanthrene
2-nitronaphthalene
propane sultone
various N-nitrosamides
various N-nitrosamines

Record of the amounts of substances of high chronic toxicity being stored and the amounts used, dates of use, and names of users. It is appropriate to keep such records as part of the record of project work in the laboratory workers’ research notebook, but it must be understood that the research supervisor is responsible for ensuring that accurate records are maintained.

Any volatile substances having high chronic toxicity must be stored in a ventilated storage area in a secondary tray or container having sufficient capacity to contain the material should the primary storage container fail. All containers of substances in this category should have labels that identify the contents and include a warning such as: WARNING! HIGHLY TOXIC OR SUSPECTED CARCINOGEN. Storage areas for substances in this category must have limited access, and special signs should be posted if a special toxicity hazard exists. Any area used for storage of substances of high chronic toxicity must be maintained under negative pressure with respect to the surroundings. Contact EHS if there is a problem with airflow in the storage areas.

All projects with and transfers of such substances or mixtures containing such substances must be done in a controlled area (i.e., a laboratory, or a portion of a laboratory, or a facility such as an exhaust hood or a glove box that is designated for the use of highly toxic substances. Its use need not be restricted to the handling of highly toxic substances if all personnel who have access to the controlled area are aware of the nature of the substances being used and the precautions that are necessary). When a glove box is used, the ventilation rate in the box should be at least two volume changes per hour, the pressure should be at least 0.5 inches of water lower than that of the surrounding environment, and the exhaust should be passed through a trap, charcoal or High Efficiency Particulate Air (HEPA) filter as appropriate.

Positive pressure glove boxes are normally used to provide an inert anhydrous atmosphere. If these glove boxes are used with highly toxic compounds, then the box should be thoroughly checked for leaks before use and the exit gases should be passed through a suitable trap or filter. Laboratory vacuum pumps used with substances having high chronic toxicity should be protected by high-efficiency scrubbers or HEPA filters and vented into an exhaust hood. Motor-driven vacuum pumps are recommended because they are easy to decontaminate.

Proper gloves must be worn when transferring or otherwise handling substances or solutions of substances having high chronic toxicity. In some cases, the laboratory worker or the research supervisor may deem it necessary to use other protective apparel, such as an apron of reduced permeability covered by a disposable coat. Additional precautions such as these might be taken, for example, when handling large amounts of certain heavy metals and their derivatives or known potent carcinogens.

Surfaces on which high chronic toxicity substances are handled must be protected from contamination by chemically resistant trays or pans that can be decontaminated after the project or by using dry, absorbent plastic-backed paper.

On leaving a controlled area, laboratory workers must remove any used PPE and thoroughly wash hands, forearms, face, and neck. If disposable apparel or absorbent paper liners have been used, these items must be placed in a closed and impervious container that should then be labeled in some manner such as: CAUTION: CONTENTS CONTAMINATED WITH SUBSTANCES OF HIGH CHRONIC TOXICITY (for waste disposal purposes, chemical names are required). Non-disposable protective apparel should be thoroughly washed, and containers of non reusable apparel and protective liners must be disposed of through EHS.

Wastes and residues must be placed in an impervious container and disposed of through EHS. In general, liquid wastes containing such compounds must be placed in a glass or polyethylene bottle half filled with vermiculite.

Normal laboratory work must not be resumed in a space that has been used as a controlled area until it has been adequately decontaminated. Work surfaces must be thoroughly washed and rinsed. If projects have involved the use of finely divided solid materials, dry sweeping should not be done. In such cases, surfaces must be cleaned by wet mopping or by use of a vacuum cleaner equipped with a HEPA filter. All equipment (e.g., glassware, vacuum pumps, and containers) that is known or suspected to have been in contact with substances of high chronic toxicity should be washed and rinsed before removing from the controlled area.

In the event of continued exposure to a substance of high chronic toxicity (i.e., if a worker regularly uses significant quantities of such a substance at least three times a week), Occupational Health should be consulted to determine whether it is advisable to establish a regular schedule of medical surveillance or biological monitoring.

In addition to the precautions described in this section, lab supervisors must develop written standard operating procedures intended to establish a concise, step-by-step method for carrying out routine laboratory operations with the substance in question. These procedures should be reviewed by a department laboratory safety coordinator or EHS.