Current through Register 2022 Notice Reg. No. 16, April 25, 2022
Recommendations Concerning Chemical Hygiene in
Table of Contents
Corresponding Sections of the Regulation and This
Minimize all Chemical Exposures
Avoid Underestimation of Risk
Provide Adequate Ventilation
Institute Chemical Hygiene Program
Observe the exposure limits and
Chief Executive Officer
Supervisor of Administrative Unit
Chemical Hygiene Officer
The Laboratory Facility
Components of the Chemical Hygiene
Basic Rules and Procedures
Chemical Procurement, Distribution, and
Housekeeping, Maintenance and
Personal Protective Apparel and
Signs and Labels
Spills and Accidents
Training and Information
General Procedures for Working With
General Rules for all Laboratory Work with
Allergens and Embryotoxins
Chemicals of Moderate Chronic or High Acute
Chemicals of High Chronic Toxicity
Animal Work with Chemicals of High Chronic
Safety Data Sheets
As guidance for each employer's development of an
appropriate laboratory Chemical Hygiene Plan, the following non-mandatory
recommendations are provided. They were extracted from "Prudent Practices for
Handling Hazardous Chemicals in Laboratories" (referred to below as "Prudent
Practices"), which was published in 1981 by the National Research Council and
is available from the National Academy Press, 2101 Constitution Ave., NW.,
Washington DC 20418.
"Prudent Practices" is cited because of its wide
distribution and acceptance and because of its preparation by members of the
laboratory community through the sponsorship of the National Research Council.
However, none of the recommendations given here will modify any requirements of
the laboratory regulation. This Appendix merely presents pertinent
recommendations from "Prudent Practices," organized into a form convenient for
quick reference during development and application of a Chemical Hygiene Plan.
Users of this appendix should consult "Prudent Practices" for a more extended
presentation and justification for each recommendation.
"Prudent Practices" deals with both safety and chemical
hazards while the laboratory regulation is concerned primarily with chemical
hazards. Therefore, only those recommendations directed primarily toward
control of toxic exposures are cited in this appendix, with the term "chemical
hygiene" being substituted for the word "safety." However, since conditions
producing or threatening physical injury often pose toxic risks as well, page
references concerning major categories of safety hazards in the laboratory are
given in section F.
The recommendations from "Prudent Practices" have been
paraphrased, combined, or otherwise reorganized, and headings have been added.
However, their sense has not been changed.
Corresponding Sections of the Regulation and this
The following table is given for the convenience of
those who are developing a Chemical Hygiene Plan which will satisfy the
requirements of subsection 5191(e). It indicates those sections of this
appendix which are most pertinent to each of the sections of subsection 5191(e)
and related paragraphs.
Paragraph and topic in
(e) (3) (A) Standard operating procedures
handling toxic chemicals.
C, D, E
(e) (3) (B) Criteria to be used for
of measures to reduce exposures.
(e) (3) (C) Fume hood performance
(e) (3) (D) Employee information and
(including emergency procedures).
(e) (3) (E) Requirements for prior approval of
(e) (3) (F) Medical consultation and medical
(e) (3) (G) Chemical hygiene
(e) (3) (H) Special precautions for work
particularly hazardous substances.
In this appendix, those recommendations directed
primarily at administrators and supervisors are given in sections A - D. Those
recommendations of primary concern to employees who are actually handling
laboratory chemicals are given in section E. (Reference to page numbers in
"Prudent Practices" are given in parentheses.)
General Principles for Work with Laboratory
In addition to the more detailed recommendations listed
below in sections B-E, "Prudent Practices" expresses certain general
principles, including the following:
1.It is prudent to minimize all chemical
exposures. Because few laboratory chemicals are without hazards, general
precautions for handling all laboratory chemicals should be adopted, rather
than specific guidelines for particular chemicals (2,10). Skin contact with
chemicals should be avoided as a cardinal rule (198).
2.Avoid underestimation of risk. Even for
substances of no known significant hazard, exposure should be minimized; for
work with substances which present special hazards, special precautions should
be taken (10, 37, 38). One should assume that any mixture will be more toxic
than its most toxic component (30, 103) and that all substances of unknown
toxicity are toxic (3, 34).
3.Provide adequate ventilation. The best way
to prevent exposure to airborne substances is to prevent their escape into the
working atmosphere by use of hoods and other ventilation devices (32,
4.Institute a chemical
hygiene program. A mandatory chemical hygiene program designed to minimize
exposures is needed; it should be a regular, continuing effort, not merely a
standby or short-term activity (6,11). Its recommendations should be followed
in academic teaching laboratories as well as by full-time laboratory workers
5.Observe the exposure limits
and TLVs. The Exposure limits of Cal/OSHA and the Threshold Limit Values of the
American Conference of Governmental Industrial Hygienists should not be
Chemical Hygiene Responsibilities
Responsibility for chemical hygiene rests at all levels
(6, 11, 21) including the:
executive officer, who has ultimate responsibility for chemical hygiene within
the institution and must, with other administrators, provide continuing support
for institutional chemical hygiene (7, 11).
2.Supervisor of the department or other
administrative unit, who is responsible for chemical hygiene in that unit
Chemical hygiene officers,
whose appointment is essential (7) and who must:
(a) Work with administrators and other
employees to develop and implement appropriate chemical hygiene policies and
procurement, use, and disposal of chemicals used in the lab (8).;
(c) See that appropriate audits are
(d) Help project
directors develop precautions and adequate facilities (10);
(e) Know the current legal requirements
concerning regulated substances (50); and
(f) Seek ways to improve the chemical hygiene
program (8, 11).
Laboratory supervisor, who has overall
responsibility for chemical hygiene in the laboratory (21) including
(a) Ensure that workers
know and follow the chemical hygiene rules, that protective equipment is
available and in working order, and that appropriate training has been provided
(b) Provide regular,
formal chemical hygiene and housekeeping inspections including routine
inspections of emergency equipment (21, 171);
(c) Know the current legal requirements
concerning regulated substances (50, 231);
(d) Determine the required levels of
protective apparel and equipment (156, 160, 162); and
(e) Ensure that facilities and training for
use of any material being ordered are adequate (215).
5.Project director or director of other
specific operation, who has primary responsibility for chemical hygiene
procedures for that operation (7).
Laboratory worker, who is responsible for:
(a) Planning and conducting each operation in
accordance with the institutional and chemical hygiene procedures (7, 21, 22,
(b) Developing good
personal chemical hygiene habits (22).
The Laboratory Facility
Design. The laboratory facility should
(a) An appropriate general ventilation
system (see C4 below) with air intakes and exhausts located so as to avoid
intake of contaminated air (194);
(b) Adequate, well-ventilated
stockrooms/storerooms (218, 219).
(c) Laboratory hoods and sinks (12,
(d) Other safety equipment
including eyewash fountains and drench showers (162, 169): and
(e) Arrangements for waste disposal (12,
Chemical-hygiene-related equipment (hoods, incinerator, etc.) should undergo
continual appraisal and be modified if inadequate (11, 12).
3.Usage. The work conducted (10) and its
scale (12) must be appropriate to the physical facilities available and,
especially, to the quality of ventilation (13).
General laboratory ventilation.
This system should; Provide a source of air for
breathing and for input to local ventilation devices (199); it should not be
relied on for protection from toxic substances released into the laboratory
(198); ensure that laboratory air is continually replaced, preventing increase
of air concentrations of toxic substances during the working day (194); direct
air flow into the laboratory from non-laboratory areas and out to the exterior
of the building (194).
Hoods. A laboratory hood with 2.5 linear feet of hood space per person should
be provided for every 2 workers if they spend most of their time working with
chemicals (199); each hood should have a continuous monitoring device to allow
convenient confirmation of adequate hood performance before use (200, 209). If
this is not possible, work with substances of unknown toxicity should be
avoided (13) or other types of local ventilation devices should be provided
(199). See pp. 201-206 for a discussion of hood design, construction, and
(c) Other local
ventilation devices. Ventilated storage cabinets, canopy hoods, snorkels, etc.
should be provided as needed (199). Each canopy hood and snorkel should have a
separate exhaust duct (207).
Special ventilation areas. Exhaust air from glove boxes and isolation rooms
should be passed through scrubbers or other treatment before release into the
regular exhaust system (208). Cold rooms and warm rooms should have provisions
for rapid escape and for escape in the event of electrical failure
(e) Modifications. Any
alteration of the ventilation system should be made only if thorough testing
indicates that worker protection from airborne toxic substances will continue
to be adequate (12, 193, 204).
Performance. Rate: 4-12 room air changes/hour is normally adequate general
ventilation if local exhaust systems such as hoods are used as the primary
method of control (194).
Quality. General air flow should not be turbulent and should be relatively
uniform throughout the laboratory, with no high velocity or static areas (194,
195); airflow into and within the hood should not be excessively turbulent
(200); hood face velocity should be adequate (typically 60-100 lfm) (200,
(h) Evaluation. Quality and
quantity of ventilation should be evaluated on installation (202), regularly
monitored (at least every 3 months) (6, 12, 14, 195), and reevaluated whenever
a change in local ventilation devices is made (12, 195, 207). See pp 195-198
for methods of evaluation and for calculation of estimated airborne contaminant
Components of the Chemical Hygiene Plan
1.Basic Rules and Procedures (Recommendations
for these are given in section E, below)
Chemical Procurement, Distribution, and
(a) Procurement. Before a substance
is received, information on proper handling, storage, and disposal should be
known to those who will be involved (215, 216). No container should be accepted
without an adequate identifying label (216). Preferably, all substances should
be received in a central location (216).
Stockrooms/storerooms. Toxic substances
should be segregated in a well-identified area with local exhaust ventilation
(221). Chemicals which are highly toxic (227) or other chemicals whose
containers have been opened should be in unbreakable secondary containers
(219). Stored chemicals should be examined periodically (at least annually) for
replacement, deterioration, and container integrity (218-19).
Stockrooms/storerooms should not be used as preparation
or repackaging areas, should be open during normal working hours, and should be
controlled by one person (219).
(c) Distribution. When chemicals are hand
carried, the container should be placed in an outside container or bucket.
Freight-only elevators should be used if possible (223).
(d) Laboratory storage. Amounts permitted
should be as small as practical. Storage on bench tops and in hoods is
inadvisable. Exposure to heat or direct sunlight should be avoided. Periodic
inventories should be conducted, with unneeded items being discarded or
returned to the storeroom/stockroom (225-6, 229).
Regular instrumental monitoring of airborne
concentrations is not usually justified or practical in laboratories but may be
appropriate when testing or redesigning hoods or other ventilation devices (12)
or when a highly toxic substance is stored or used regularly (e.g., 3
Housekeeping, Maintenance, and Inspections
(a) Cleaning. Floors should be cleaned
Formal housekeeping and chemical hygiene inspections should be held at least
quarterly (6, 21) for units which have frequent personnel changes and
semiannually for others; informal inspections should be continual
(c) Maintenance. Eye wash
fountains should be inspected at intervals of not less than 3 months (6).
Respirators for routine use should be inspected periodically by the laboratory
supervisor (169). Safety showers should be tested routinely (169). Other safety
equipment should be inspected regularly, (e.g., every 3-6 months) (6, 24, 171).
Procedures to prevent restarting of out-of-service equipment should be
Stairways and hallways should not be used as storage areas (24). Access to
exits, emergency equipment, and utility controls should never be blocked
(a) Compliance with regulations. Regular
medical surveillance should be established to the extent required by
surveillance. Anyone whose work involves regular and frequent handling of
toxicologically significant quantities of a chemical should consult a qualified
physician to determine on an individual basis whether a regular schedule of
medical surveillance is desirable (11, 50).
(c) First aid. Personnel trained in first aid
should be available during working hours and an emergency room with medical
personnel should be nearby (173). See pp. 176-178 for description of some
emergency first aid procedures.
Protective Apparel and Equipment. These
should include for each laboratory:
Protective apparel compatible with the required degree of protection for
substances being handled (158-161);
(b) An easily accessible drench-type safety
shower (162, 169);
(c) An eyewash
(d) A fire
Respiratory protection (164-9), fire alarm and telephone for emergency use
(162) should be available nearby; and
(f) Other items designated by the laboratory
supervisor (156, 160).
(a) Accident records should be written and
Hygiene Plan records should document that the facilities and precautions were
compatible with current knowledge and regulations (7).
(c) Inventory and usage records for high-risk
substances should be kept as specified in sections E3e below.
(d) Medical records should be retained by the
institution in accordance with the requirements of state and federal
Signs and Labels
Prominent signs and labels of the following types
should be posted:
telephone numbers of emergency personnel/facilities, supervisors, and
laboratory workers (28);
Identity labels, showing contents of containers (including waste receptacles)
and associated hazards (27, 48);
(c) Location signs for safety showers,
eyewash stations, other safety and first aid equipment, exits (27) and areas
where food and beverage consumption and storage are permitted (24);
(d) Warnings at areas or
equipment where special or unusual hazards exist (27).
Spills and Accidents
(a) A written emergency plan should be
established and communicated to all personnel; it should include procedures for
ventilation failure (200), evacuation, medical care, reporting, and drills
(b) There should be an alarm
system to alert people in all parts of the facility including isolation areas
such as cold rooms (172).
spill control policy should be developed and should include consideration of
prevention, containment, cleanup, and reporting (175).
(d) All accidents or near accidents should be
carefully analyzed with the results distributed to all who might benefit (8,
(a) Aim: To ensure that all
individuals at risk are adequately informed about the work in the laboratory,
its risks, and what to do if an accident occurs (5, 15).
(b) Emergency and Personal Protection
Training: Every laboratory worker should know the location and proper use of
available protective apparel and equipment (154, 169). Some of the full-time
personnel of the laboratory should be trained in the proper use of emergency
equipment and procedures (6). Such training as well as first aid instruction
should be available to (154) and encouraged for (176) everyone who might need
(c) Receiving and
stockroom/storeroom personnel should know about hazards, handling equipment,
protective apparel, and relevant regulations (217).
(d) Frequency of Training: The training and
education program should be a regular, continuing activity - not simply an
annual presentation (15).
Literature/Consultation: Literature and consulting advice concerning chemical
hygiene should be readily available to laboratory personnel, who should be
encouraged to use these information resources (14).
Waste Disposal Program.
(a) Aim: to ensure that minimal harm to
people, other organisms, and the environment will result from the disposal of
waste laboratory chemicals (5).
Content (14, 232, 233, 240): The waste disposal program should specify how
waste is to be collected, segregated, stored, and transported and include
consideration of what materials can be incinerated. Transport from the
institution must be in accordance with DOT regulations (244).
(c) Discarding Chemical Stocks: Unlabeled
containers of chemicals and solutions should undergo prompt disposal; if
partially used, they should not be opened (24, 27). Before a worker's
employment in the laboratory ends, chemicals for which that person was
responsible should be discarded or returned to storage (226).
(d) Frequency of Disposal: Waste should be
removed from laboratories to a central waste storage area at least once per
week and from the central waste storage area at regular intervals
Method of Disposal:
Incineration in an environmentally acceptable manner is the most practical
disposal method for combustible laboratory waste (14, 238, 241).
Indiscriminate disposal by pouring waste chemicals down
the drain (14, 231, 242) or adding them to mixed refuse for landfill burial is
Hoods should not be used as a means of disposal for
volatile chemicals (40, 200).
Disposal by recycling (233, 243) or chemical
decontamination (40, 230) should be used when possible.
Basic Rules and
Procedures for Working with Chemicals.
The Chemical Hygiene Plan should require that
laboratory workers know and follow its rules and procedures. In addition to the
procedures of the sub programs mentioned above, these should include the rules
The following should be used for essentially all
laboratory work with chemicals:
Accidents and spills - Eye Contact: Promptly flush eyes with water for a
prolonged period (15 minutes) and seek medical attention (33, 172).
Ingestion: This is one route of entry for which
treatment depends on the type and amount of chemical involved. Seek medical
Skin Contact: Promptly flush the affected area with
water (33, 172, 178). and remove any contaminated clothing (172, 178). If
symptoms persist after washing, seek medical attention (33).
Clean-up: Promptly clean up spills, using appropriate
protective apparel and equipment and proper disposal (24, 33). See pp., 233-237
for specific clean-up recommendations.
Avoidance of "routine" exposure: Develop
and encourage safe habits (23); avoid unnecessary exposure to chemicals by any
Do not smell or taste chemicals (32). Vent apparatus
which may discharge toxic chemicals (vacuum pumps, distillation columns, etc.)
into local exhaust devices (199).
Inspect gloves (157) and test glove boxes (208) before
Do not allow release of toxic substances in cold rooms
and warm rooms, since these have contained recirculated atmospheres
(c) Choice of
chemicals: Use only those chemicals for which the quality of the available
ventilation system is appropriate (13).
(d) Eating, smoking, etc.: Avoid eating,
drinking, smoking, gum chewing, or application of cosmetics in areas where
laboratory chemicals are present (22, 24, 32, 40); wash hands before conducting
these activities (23, 24). Avoid storage, handling, or consumption of food or
beverages in storage areas, refrigerators, glassware or utensils which are also
used for laboratory operations (23, 24, 226).
(e) Equipment and glassware: Handle and store
laboratory glassware with care to avoid damage; do not use damaged glassware
(25). Use extra care with Dewar flasks and other evacuated glass apparatus;
shield or wrap them to contain chemicals and fragments should implosion occur
(25). Use equipment only for its designed purpose (23, 26).
(f) Exiting: Wash areas of exposed skin well
before leaving the laboratory (23).
(g) Horseplay: Avoid practical jokes or other
behavior which might confuse, startle or distract another worker
(h) Mouth suction: Do not use
mouth suction for pipeting or starting a siphon (23, 32).
(i) Personal apparel: Confine long hair and
loose clothing (23, 158). Wear shoes at all times in the laboratory but do not
wear sandals, perforated shoes, or sneakers (158).
(j) Personal housekeeping: Keep the work area
clean and uncluttered, with chemicals and equipment being properly labeled and
stored; clean up the work area on completion of an operation or at the end of
each day (24).
protection: Assure that appropriate eye protection (154-156) is worn by all
persons, including visitors, where chemicals are stored or handled (22, 23, 33,
Wear appropriate gloves when the potential for contact
with toxic materials exists (157); inspect the gloves before each use, wash
them before removal, and replace them periodically (157). (A table of
resistance to chemicals of common glove materials is given p. 159).
Use appropriate (164-168) respiratory equipment when
air contaminant concentrations are not sufficiently restricted by engineering
controls (164-5), inspecting the respirator before use (169).
Use any other protective and emergency apparel and
equipment as appropriate (22, 157-162).
Avoid use of contact lenses in the laboratory unless
necessary; if they are used, inform supervisor so special precautions can be
Remove laboratory coats immediately on significant
Planning: Seek information and advice about hazards (7), plan appropriate
protective procedures, and plan positioning of equipment before beginning any
new operation (22, 23).
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 (27,
Use of hood: Use the hood
for operations which might result in release of toxic chemical vapors or dust
As a rule of thumb, use a hood or other local
ventilation device when working with any appreciably volatile substance with a
TLV of less than 50 ppm (13).
Confirm adequate hood performance before use; keep hood
closed at all times except when adjustments within the hood are being made
(200); keep materials stored in hoods to a minimum and do not allow them to
block vents or air flow (200).
Leave the hood "on" when it is not in active use if
toxic substances are stored in it or if it is uncertain whether adequate
general laboratory ventilation will be maintained when it is "off"
(o) Vigilance: Be
alert to unsafe conditions and see that they are corrected when detected
Waste disposal: Assure
that the plan for each laboratory operation includes plans and training for
waste disposal (230).
Deposit chemical waste in appropriately labeled
receptacles and follow all other waste disposal procedures of the Chemical
Hygiene Plan (22, 24).
Do not discharge to the sewer concentrated acids or
bases (231); highly toxic, malodorous, or lachrymatory substances (231); or any
substances which might interfere with the biological activity of waste water
treatment plants, create fire or explosion hazards, cause structural damage or
obstruct flow (242).
Working alone: Avoid working alone in a building; do not work alone in a
laboratory if the procedures being conducted are hazardous (28).
Working with Allergens and
(a) Allergens (examples:
diazomethane, isocyanates, bichromates): Wear suitable gloves to prevent hand
contact with allergens or substances of unknown allergenic activity
(examples: organomercurials, lead compounds, formamide): If you are a woman of
childbearing age, handle these substances only in a hood whose satisfactory
performance has been confirmed, using appropriate protective apparel
(especially gloves) to prevent skin contact.
Review each use of these materials with the research
supervisor and review continuing uses annually or whenever a procedural change
Store these substances, properly labeled, in an
adequately ventilated area in an unbreakable secondary container.
Notify supervisors of all incidents of exposure or
spills; consult a qualified physician when appropriate.
Work with Chemicals of Moderate
Chronic or High Acute Toxicity
Examples: diisopropylfluorophosphate (41), hydrofluoric
acid (43), hydrogen cyanide (45).
Supplemental rules to be followed in addition to those
mentioned above (Procedure B of "Prudent Practices," pp. 39-41):
(a) Aim: To minimize exposure to these toxic
substances by any route using all reasonable precautions (39).
(b) Applicability: These precautions are
appropriate for substances with moderate chronic or high acute toxicity used in
significant quantities (39).
Location: Use and store these substances only in areas of restricted access
with special warning signs (40, 229).
Always use a hood (previously evaluated to confirm
adequate performance with a face velocity of at least 60 linear feet per
minute) (40) or other containment device for procedures which may result in the
generation of aerosols or vapors containing the substance (39); trap released
vapors to prevent their discharge with the hood exhaust (40).
(d) Personal protection: Always avoid skin
contact by uses of gloves and long sleeves (and other protective apparel as
appropriate) (39). Always wash hands and arms immediately after working with
these materials (40).
Maintain records of the amounts of these materials on hand, amounts used, and
the manes of the workers involved (40, 229).
Prevention of spills and accidents: Be
prepared for accidents and spills (41).
Ensure that at least 2 people are present at all times
if a compound in use is highly toxic or of unknown toxicity (39).
Store breakable containers of these substances in
chemically resistant trays; also work and mount apparatus above such trays or
cover work and storage surfaces with removable, absorbent, plastic backed paper
If a major spill occurs outside the hood, evacuate the
area; assure that cleanup personnel wear suitable protective apparel and
Thoroughly decontaminate or incinerate contaminated clothing or shoes (41). If
possible, chemically decontaminate by chemical conversion (40).
Store contaminated waste in closed, suitably labeled,
impervious containers (for liquids, in glass or plastic bottles half-filled
with vermiculite) (40).
Work with Chemicals of High Chronic
Toxicity (Examples: dimethylmercury and nickel carbonyl (48), benzo-a-pyrene
(51), N-nitrosodiethylamine (54), other human carcinogens or substances with
high carcinogenic potency in animals (38).)
Further supplemental rules to be followed, in addition
to all these mentioned above, for work with substances of known high chronic
toxicity (in quantities above a few milligrams to a few grams, depending on the
substance) (47). (Procedure A of "Prudent Practices" pp, 47-50).
(a) Access: Conduct all transfers and work
with these substances in a "controlled area": a restricted access hood, glove
box, or portion of a lab, designated for use of highly toxic substances, for
which all people with access are aware of the substances being used and
necessary precautions (48).
Approvals: Prepare a plan for use and disposal of these materials and obtain
the approval of the laboratory supervisor (48).
Protect vacuum pumps against contamination by scrubbers or HEPA filters and
vent them into the hood (49). Decontaminate vacuum pumps or other contaminated
equipment, including glassware, in the hood before removing them from the
controlled area (49, 50). Decontaminate the controlled area before normal work
is resumed there (50).
On leaving a controlled area, remove any protective apparel (placing it in an
appropriate, labeled container) and thoroughly wash hands, forearms, face, and
(e) Housekeeping: Use a
wet mop or a vacuum cleaner equipped with a HEPA filter instead of dry sweeping
if the toxic substance was a dry powder (50).
(f) Medical surveillance: If using
toxicologically significant quantities of such a substance on a regular basis
(e.g., 3 times per week), consult a qualified physician concerning desirability
of regular medical surveillance (50).
(g) Records: Keep accurate records of the
amounts of these substances stored (229) and used, the dates of use, and names
of users (48).
(h) Signs and
labels: Assure that the controlled area is conspicuously marked with warning
and restricted access signs (49) and that all containers of these substances
are appropriately labeled with identity and warning labels (48).
(i) Spills: Assure that contingency plans,
equipment, and materials to minimize exposures of people and property in case
of accident are available (233-4).
(j) Storage: Store containers of these
chemicals only in a ventilated, limited access (48, 227, 229) area in
appropriately labeled, unbreakable, chemically resistant, secondary containers
(k) Glove boxes: For a
negative pressure glove box, ventilation rate must be at least 2 volume
changes/hour and pressure at least 0.5 inches of water (48). For a positive
pressure glove box, thoroughly check for leaks before each use (49). In either
case, trap the exit gases or filter them through a HEPA filter and then release
them into the hood (49).
Use chemical decontamination whenever possible; ensure that containers of
contaminated waste (including washings from contaminated flasks) are
transferred from the controlled area in a secondary container under the
supervision of authorized personnel (49, 50, 233).
Animal Work with Chemicals of High Chronic
(a) Access: For large scale studies,
special facilities with restricted access are preferable (56).
(b) Administration of the toxic substance:
When possible, administer the substance by injection or gavage instead of in
the diet. If administration is in the diet, use a caging system under negative
pressure or under laminar air flow directed toward HEPA filters (56).
(c) Aerosol suppression: Devise procedures
which minimize formation and dispersal of contaminated aerosols, including
those from food, urine, and feces (e.g., use HEPA filtered vacuum equipment for
cleaning, moisten contaminated bedding before removal from the cage, mix diets
in closed containers in a hood) (55, 56).
(d) Personal protection: When working in the
animal room, wear plastic or rubber gloves, fully buttoned laboratory coat or
jumpsuit and, if needed because of incomplete suppression of aerosols, other
apparel and equipment (shoe and head coverings, respirator) (56).
(e) Waste disposal: Dispose of contaminated
animal tissues and excreta by incineration if the available incinerator can
convert the contaminant to non-toxic products (238); otherwise, package the
waste appropriately for burial in an EPA-approved site (239).
The above recommendations from "Prudent Practices" do
not include those which are directed primarily toward prevention of physical
injury rather than toxic exposure. However, failure of precautions against
injury will often have the secondary effect of causing toxic exposures.
Therefore, we list below page references for recommendations concerning some of
the major categories of safety hazards which also have implications for
laboratory apparatus: (179-92)
3.Fires, explosions: (26, 57-74, 162-64,
174-5, 219-20, 226-7)
temperature procedures: (26, 88)
5.Pressurized and vacuum operations
(including use of compressed gas cylinders): (27, 75-101)
Safety Data Sheets
Safety data sheets are presented in "Prudent Practices"
for the chemicals listed below. (Asterisks denote that comprehensive safety
data sheets are provided).
*Acetyl peroxide (105)
Ammonia (anhydrous) (91)
*Bis(chloromethyl) ether (113)
Boron trichloride (91)
Boron trifluoride (92)
*Tert-butyl hydroperoxide (148)
*Carbon disulfide (116)
Carbon monoxide (92)
*Carbon tetrachloride (118)
Chlorine trifluoride (94)
*Diethyl ether (122)
Diisopropyl fluorophosphate (41)
*Dimethyl sulfate (125)
*Ethylene dibromide (128)
*Hydrazine and salts (132)
Hydrofluoric acid (43)
Hydrogen bromide (98)
Hydrogen chloride (98)
*Hydrogen cyanide (133)
*Hydrogen sulfide (135)
Mercury and compounds (52)
*Nickel carbonyl (99)
Nitrogen dioxide (100)
*Peracetic acid (141)
*Sodium azide (145)
*Sodium cyanide (147)
Sulfur dioxide (101)
*Vinyl choride (150)