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* NIOSH POCKET GUIDE TO CHEMICAL HAZARDS *
* *
* Produced by: US National Institute for Occupational Safety and Health *
* Provided by: Canadian Centre for Occupational Health and Safety *
* * * * * * * * * * * * * * * * * * * * * * * Issue : 99-2 (May, 1999) *
CHEMICAL NAME : Benzene
SYNONYMS : Benzol
Phenyl hydride
CAS REGISTRY NUMBER : 71-43-2
RTECS NUMBER : CY1400000
DOT/NAERG NUMBERS : 1114 / 130
CCOHS RECORD NUMBER : 49
MOLECULAR FORMULA : C6H6
DESCRIPTION : Colorless to light-yellow liquid with an aromatic odor.
DESCRIPTION NOTE : A solid below 42 deg F.
*** EXPOSURE LIMITS ***
CONVERSION FACTOR :
1 ppm = 3.19 mg/m3 at 25 deg C and 1 atmosphere
NIOSH RECOMMENDED EXPOSURE LIMITS (REL)
TIME WEIGHTED AVERAGE (TWA) : 0.1 ppm
SHORT TERM EXPOSURE LIMIT (STEL) : 1 ppm
NOTE : See Appendix A
OSHA CURRENT PERMISSIBLE EXPOSURE LIMITS (PEL)
[1910.1028]
TIME WEIGHTED AVERAGE (TWA) : 1 ppm
SHORT TERM EXPOSURE LIMIT (STEL) : 5 ppm
NOTE : See Appendix F
OSHA 1989 (VACATED) PERMISSIBLE EXPOSURE LIMITS (PEL)
[1910.1028]
TIME WEIGHTED AVERAGE (TWA) : 1 ppm
SHORT TERM EXPOSURE LIMIT (STEL) : 5 ppm
NOTE : See Appendix F
IDLH CONCENTRATION : Potential NIOSH carcinogen.
[500 ppm]
*** RESPIRATORY PROTECTION ***
RECOMMENDATIONS FOR RESPIRATOR SELECTION
BASED ON NIOSH REL
AT CONCENTRATIONS ABOVE THE NIOSH REL, OR WHERE THERE IS NO REL, AT ANY DETECTABLE CONCENTRATION:
Any self-contained breathing apparatus that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode (APF = 10,000)
OR Any supplied-air respirator that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode in combination with an auxiliary self-contained breathing apparatus operated in pressure-demand or other positive-pressure mode (APF = 10,000)
ESCAPE:
Any air-purifying, full-facepiece respirator (gas mask) with a chin-style, front- or back-mounted organic vapor canister (APF = 50)
OR Any appropriate escape-type, self-contained breathing apparatus
*** PERSONAL PROTECTION AND SANITATION ***
SKIN PROTECTION :
Wear appropriate personal protective clothing to prevent skin contact.
EYE PROTECTION :
Wear appropriate eye protection to prevent eye contact.
SKIN CLEAN-UP :
The worker should immediately wash the skin when it becomes contaminated.
CLOTHING/PPE REMOVAL :
Work clothing that becomes wet should be immediately removed due to its flammability hazard (i.e., for liquids with a flash point <100 deg F).
CLOTHING/PPE CHANGE :
No recommendation is made specifying the need for the worker to change clothing after the workshift.
PPE FACILITIES :
Eyewash fountains should be provided in areas where there is any possibility that workers could be exposed to the substances; this is irrespective of the recommendation involving the wearing of eye protection., Facilities for quickly drenching the body should be provided within the immediate work area for emergency use where there is a possibility of exposure.
*** HEALTH HAZARDS AND FIRST AID ***
POTENTIAL ROUTES OF EXPOSURE :
Inhalation; Skin absorption; Ingestion; Skin and/or eye contact
POTENTIAL SYMPTOMS OF EXPOSURE :
Irritation eyes, skin, nose, respiratory system; giddiness; headache, nausea, staggered gait; fatigue, anorexia, lassitude (weakness, exhaustion); dermatitis; bone marrow depressant/depression; potential occupational carcinogen
TARGET ORGANS :
Eyes, skin, respiratory system, blood, central nervous system, bone marrow
POTENTIAL OCCUPATIONAL CARCINOGEN :
leukemia
EYES - FIRST AID :
If this chemical contacts the eyes, immediately wash the eyes with large amounts of water, occasionally lifting the lower and upper lids. Get medical attention immediately. Contact lenses should not be worn when working with this chemical.
SKIN - FIRST AID :
If this chemical contacts the skin, immediately wash the contaminated skin with soap and water. If this chemical penetrates the clothing, immediately remove the clothing, wash the skin with soap and water, and get medical attention promptly.
INHALATION - FIRST AID :
If a person breathes large amounts of this chemical, move the exposed person to fresh air at once. If breathing has stopped, perform mouth-to-mouth resuscitation. Keep the affected person warm and at rest. Get medical attention as soon as possible.
INGESTION - FIRST AID :
If this chemical has been swallowed, get medical attention immediately.
*** PHYSICAL AND CHEMICAL PROPERTIES ***
MOLECULAR WEIGHT : 78.1
BOILING POINT : 176 deg F
FREEZING POINT : 42 deg F
SOLUBILITY : 0.07 percent
VAPOR PRESSURE : 75 mmHg
SPECIFIC GRAVITY : 0.88
FLASH POINT : 12 deg F
LOWER EXPLOSIVE LIMIT : 1.2 percent
UPPER EXPLOSIVE LIMIT : 7.8 percent
IONIZATION POTENTIAL : 9.24 eV
FLAMMABILITY CLASS :
Class IB Flammable Liquid
INCOMPATIBILITIES AND REACTIVITIES :
Strong oxidizers, many fluorides & perchlorates, nitric acid
MEASUREMENT METHOD :
Charcoal tube; Carbon disulfide; Gas chromatography with flame ionization detection; NIOSH Manual of Analytical Methods (NMAM), 4th edition [#1500, Hydrocarbons] [Also #3700, #1501]
*** EXPOSURE LIMIT APPENDICES ***
NIOSH REL NOTES
Appendix A:
New Policy
For the past 20 plus years, NIOSH has subscribed to a carcinogen policy
that was published in 1976 by Edward J. Fairchild, II, Associate Director
for Cincinnati Operations, which called for "no detectable exposure levels
for proven carcinogenic substances" (Annals of the New York Academy of
Sciences, 271:200-207, 1976). This was in response to a generic OSHA
rulemaking on carcinogens. Because of advances in science and in
approaches to risk assessment and risk management, NIOSH has adopted a more
inclusive policy. NIOSH recommended exposure limits (RELs) will be based
on risk evaluations using human or animal health effects data, and on an
assessment of what levels can be feasibly achieved by engineering controls
and measured by analytical techniques. To the extent feasible, NIOSH will
project not only a no-effect exposure, but also exposure levels at which
there may be residual risks. This policy applies to all workplace hazards,
including carcinogens, and is responsive to Section 20(a)(3) of the
Occupational Safety and Health Act of 1970, which charges NIOSH to ". .
.describe exposure levels that are safe for various periods of employment,
including but not limited to the exposure levels at which no employee will
suffer impaired health or functional capacities or diminished life
expectancy as a result of his work experience."
.
The effect of this new policy will be the development, whenever possible,
of quantitative RELs that are based on human and/or animal data, as well as
on the consideration of technological feasibility for controlling workplace
exposures to the REL. Under the old policy, RELs for most carcinogens were
non-quantitative values labeled "lowest feasible concentration (LFC)."
[Note: There are a few exceptions to LFC RELs for carcinogens (e.g., RELs
for asbestos, formaldehyde, benzene, and ethylene oxide are quantitative
values based primarily on analytical limits of detection or technological
feasibility). Also, in 1989, NIOSH adopted several quantitative RELs for
carcinogens from OSHA's permissible exposure limit (PEL) update.]
.
Under the new policy, NIOSH will also recommend the complete range of
respirators (as determined by the NIOSH Respirator Decision Logic) for
carcinogens with quantitative RELs. In this way, respirators will be
consistently recommended regardless of whether a substance is a carcinogen
or a non-carcinogen.
.
Old Policy
In the past, NIOSH identified numerous substances that should be treated as
potential occupational carcinogens even though OSHA might not have
identified them as such. In determining their carcinogenicity, NIOSH used
the OSHA classification outlined in 29 CFR 1990.103, which states in part:
.
"Potential occupational carcinogen means any substance, or combination or
mixture of substances, which causes an increased incidence of benign and/or
malignant neoplasms, or a substantial decrease in the latency period
between exposure and onset of neoplasms in humans or in one or more
experimental mammalian species as the result of any oral, respiratory or
dermal exposure, or any other exposure which results in the induction of
tumors at a site other than the site of administration. This definition
also includes any substance which is metabolized into one or more potential
occupational carcinogens by mammals."
.
When thresholds for carcinogens that would protect 100 percent of the
population had not been identified, NIOSH usually recommended that
occupational exposures to carcinogens be limited to the lowest feasible
concentration. To ensure maximum protection from carcinogens through the
use of respiratory protection, NIOSH also recommended that only the most
reliable and protective respirators be used. These respirators include (1)
a self-contained breathing apparatus (SCBA) that has a full facepiece and
is operated in a positive-pressure mode, or (2) a supplied-air respirator
that has a full facepiece and is operated in a pressure-demand or other
positive-pressure mode in combination with an auxiliary SCBA operated in a
pressure-demand or other positive-pressure mode.
OSHA PEL NOTES
Appendix F: The final Benzene standard in 1910.1028 applies to all occupational exposures to benzene except some subsegments of
industry where exposures are consistently under the action level (i.e., distribution and sales of fuels, sealed containers and
pipelines, coke production, oil and gas drilling and production, natural gas processing, and the percentage exclusion for liquid
mixtures); for the excepted subsegments, the benzene limits in Table Z-2 apply (i.e., an 8-hour TWA of 10 ppm, an acceptable
ceiling of 25 ppm, and 50 ppm for a maximum duration of 10 minutes as an acceptable maximum peak above the acceptable ceiling).
*** END OF RECORD ***