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

Housekeeping and Decontamination

  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:

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
  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

Assembly of Laboratory Apparatus


untraviolet light symbol

Ultraviolet Lamps

laser symbol


Separatory Funnels

Cryogens, Cooling Baths and Cold Traps

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)




  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

Face shields

face shield required symbol

Protective Gloves

gloves required symbol

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


closed toed shoes required symbol
respirator required symbol  respiratory protectin required symbol

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.

Proper Use of Fume Hoods

  1. Storage of Chemicals in the Lab
    Refer to the section on laboratory chemical storage in Chapter C.1.
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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.

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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:

Heavy Metals
Carbon Tetrachloride

Azo dyes
Propylene glycol

Nitrous oxide

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:

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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

   Ethylene Imine

Diazo, Azo, and Azoxy Compounds

Electrophilic Alkenes and Alkynes
   Ethyl Acrylate

   Ethylene Oxide
   Propylene Oxide
   Styrene Oxide

   Diethyl Sulfate
   Dimethyl Sulfate
   Ethyl Methanesulfonate
   Methyl Methanesulfonate
   Methyl Trifluoromethanesulfonate

Acylating Agents:
   β –Butyrolactone
   β -Propiolactone
   Dimethylcarbamoyl Chloride

Aromatic Amines:

Organohalogen Compounds:
   Bis(2-Chloroethyl) Sulfide
   Vinyl Chloride
   Methyl Iodide
   Carbon Tetrachloride

Natural Products:

Inorganic Compounds:

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.

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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:

aflatoxin B1
bis(chloromethyl) ether
dimethylcarbamoyl chloride

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.

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