SECTION 7: Safe Work Practices and Procedures
As a matter of good practice, and to satisfy regulatory requirement, particularly
hazardous substances require additional planning and considerations.
A list of particularly hazardous substances is available in Appendix
A of this manual. This list is not exhaustive; consult the material
safety data sheet to determine whether a particular chemical may be considered
a carcinogen, reproductive hazard or substance with a high acute toxicity.
The OSHA Laboratory Standard defines particularly hazardous substances as:
- Carcinogens – A carcinogen is
a substance capable of causing cancer. Carcinogens are chronically
substances; that is, they cause damage after repeated or long-duration
exposure, and their effects may become evident only after a long
A chemical is considered a carcinogen, for the purpose of the Laboratory
Safety Manual, if it is included in any of the following carcinogen lists:
- OSHA-regulated carcinogens as listed in Subpart
Z of the OSHA standards. The current list of substances that OSHA regulates as carcinogens or potential carcinogens follows:
- Methyl chloromethyl ether
- 3,3'-Dichlorobenzidine (and its salts)
- bis-Chloromethyl ether
- Vinyl chloride
- Inorganic arsenic
- Coke oven emissions
- Ethylene oxide
- Methylene Chloride
- Under the category "known to be carcinogens" in the Annual Report
of Carcinogens published by the National
Toxicology Program (NTP)
- Group 1 ("carcinogenic to humans") of the International
Agency for Research on Cancer (IARC),
latest edition. Chemicals listed in Group 2A or 2B ("reasonably anticipated
to be carcinogens") that cause significant tumor incidence
in experimental animals under specified conditions are also
under the OSHA Laboratory Standard.
- Reproductive Toxins – Reproductive
toxins are substances that have adverse effects on various aspects
reproduction, including fertility, gestation, lactation, and general
reproductive performance. When a pregnant woman is exposed to a
chemical, the fetus may be exposed as well because the placenta is
poor barrier to chemicals. Reproductive toxins can affect both
women. Male reproductive toxins can in some cases lead to sterility.
- Substances with a High Acute Toxicity – High
acute toxicity includes any chemical that falls within any of the
following OSHA-defined categories:
- A chemical with a median lethal dose (LD50)
of 50 mg or less per kg of body weight when administered
orally to certain test populations.
- A chemical with an LD50 of 200 mg less per kg
of body weight when administered by continuous contact
for 24 hours to certain
- A chemical with a median lethal concentration (LC50)
in air of 200 parts per million (ppm) by volume or less
of gas or
vapor, or 2 mg per liter or less of mist, fume, or dust,
when administered to certain test populations by continuous inhalation
for one hour,
provided such concentration and/or condition are likely
be encountered by humans when the chemical is used in
any reasonably foreseeable
Laboratory workers planning to use a particularly hazardous substance must
first receive explicit written approval from their Principal Investigator
and/or Chemical Hygiene Officer, per the Departmental Chemical Hygiene Plan.
The following steps must be taken:
1. Laboratory workers must complete a Particularly
Hazardous Substance Use Approval form. Information required
on the form includes:
- Identity, physical characteristics, and health hazards of the
- Consideration of exposure controls such as fume hoods, glove
boxes and personal protective equipment
- Designation of an area (hood, glove box, portion of lab, entire
lab) specifically for experimental procedures with the substances
- Plans for storage and secondary containment
- Procedures for safe removal of contaminated waste
- Decontamination procedures
2. The laboratory worker submits the form to the Chemical Hygiene Officer
and/or Principal Investigator and receives approval.
3. The area where the PHS will be used is
posted as a designated area. Signs for this
purpose are available through EHS or may be made by the department or
laboratory worker, as long as it includes the following information:
for select carcinogens, reproductive toxins and high acute toxicity chemicals
AUTHORIZED PERSONNEL ONLY
4. The laboratory worker proceeds with the experiment, following
the practices outlined in the Particularly Hazardous Substance Use
Approval form, as well as the appropriate work practices included
in the remainder of the Safe Work Practices and Procedures section
of this manual. All work is conducted within the Designated Area.
5. The laboratory worker decontaminates all equipment
and disposes of waste promptly, as outlined in the Particularly Hazardous
Substance Use Approval form.
Working Safely with
Particularly Hazardous Substances
The increased hazard risk associated with Particularly Hazardous Substances
(PHS) calls for more strict operating procedures in the laboratory:
- There should be no eating, drinking, smoking, chewing of gum or
tobacco, application of cosmetics or storage of utensils, food or
in laboratory areas where PHS are used or stored.
- All personnel should wash their hands and arms immediately after
the completion of any procedure in which a PHS has been used and
they leave the laboratory.
- Each procedure should be conducted with the minimum amount of
the substance, consistent with the requirements of the work.
- The laboratory worker should keep records of the amounts of each
highly hazardous material used, the dates of use and the names of
- Work surfaces, including fume hoods, should be fitted with a removable
liner of absorbent plastic-backed paper to help contain spilled materials
and to simplify subsequent cleanup and disposal.
- PHS may require more stringent use of personal protective equipment.
Check the MSDS for information on proper gloves, lab clothing and
- Proper personal protective equipment must be worn at all times
when handling PHS.
- Lab clothing that protects street clothing, such as a fully fastened
lab coat or a disposable jumpsuit, should be worn when PHS are being
used. Laboratory clothing used while manipulating PHS should not
worn outside the laboratory area.
- When methods for decontaminating clothing are unknown or not applicable,
disposable protective clothing should be worn. Disposable gloves
be discarded after each use and immediately after overt contact
with a PHS.
- Most PHS work should be performed in a fume
hood, glove box, or other form of ventilation. If the chemical
may produce vapors, mists or fumes, or if the procedure may cause
of aerosols, use of a fume hood is required.
- A fume hood used for PHS must have an average face velocity of
between 95 and 125 feet per minute. This measurement is noted on
the hood survey
sticker. If the hood has not been inspected within the past year,
contact EHS at 8-5294 for re-inspection before using the hood.
- A glove box should be used if protection from atmospheric moisture
or oxygen is needed or when a fume hood may not provide adequate
from exposure to the substance; e.g., a protection factor of
10,000 or more is needed.
- Highly toxic gases must
be used and stored in a vented gas cabinet connected to a laboratory
Gas feed lines operating above atmospheric pressure must use
- Stock quantities of PHS should be stored in a designated storage
area or cabinet with limited access. Additional storage precautions
(i.e., a refrigerator, a hood, a flammable liquid storage cabinet)
be required for certain compounds based upon other properties.
- Containers must be clearly labeled.
- Double containment should also be considered. Double containment
means that the container will be placed inside another container
is capable of holding the contents in the event of a leak and
provides a protective outer covering in the event of contamination
of the primary
- Containers should be stored on trays or pans made of polyethylene
or other chemically resistant material.
- Persons transporting PHS from one location to another should use
double containment to protect against spills and breakage.
Lines and Services
- Each vacuum service, including water aspirators, should be protected
with an absorbent or liquid trap to prevent entry of any PHS into
- When using volatile PHS, a separate vacuum pump should be used.
The procedure should be performed inside a fume hood.
- Contaminated materials should either be decontaminated by procedures
that decompose the PHS to produce a safe product or be removed for
- All work surfaces must be decontaminated at the end of the procedure
or work day, whichever is sooner.
- Prior to the start of any laboratory activity involving a PHS,
plans for the handling and ultimate disposal of contaminated
wastes and surplus
amounts of the PHS should be completed. EHS can assist in selecting
the best methods available for disposal.
7I: Laboratory Equipment