## OCCUPATIONAL SAFETY AND HEALTH GUIDELINE FOR BENZENE POTENTIAL HUMAN CARCINOGEN

INTRODUCTION
This guideline summarizes pertinent information about ben

### zene for workers, employers, and occupational safety and health professionals who may need such information to conduct effective occupational safety and health programs. Recommendations may be superseded by new developments in these fields; therefore, readers are advised to regard these recommendations as general guidelines. 

### SUBSTANCE IDENTIFICATION

• Formula: C 6H6 

### • Structure: 

# 0

• Synonyms: Benzol, benzole, benzolene, bicarburet ofhydrogen, carbon oil, coal naphtha
• Identifiers: CAS 71-43-2; RTECS C¥1400000; DOT 1114, label required: "Flammable Liquid"


### • Appearance and odor: Colorless liquid with an aromatic odor 

### CHEMICAL AND PHYSICAL PROPERTIES

• Physical data I. Molecular weight: 78.12 2. Boiling point (at 760 mmHg): 80.1 °C (176°F) 3. Specific gravity (water 

## = 1): 0.88 4. Vapor density (air = I at boiling point ofbenzene): 2.7 5. Melting point: 5.5°C (42 °F) 6. Vapor pressure at 20°C (68°F): 75 mmHg 7. Solubility in water, g/100 g water at 20°C (68°F): 0.06 8. Evaporation rate (butyl acetate = 1): 5.1 9. Saturation concentration in air (approximate) at 25

## oc (7rF): 12.5% (125,000 ppm) 10. Ionization potential: 9.25 eV


### • Reactivity Incompatibilities: Benzene reacts with strong oxidizers including chlorine, oxygen, and bromine with iron. 2. Hazardous decomposition products: Toxic vapors and gases (e.g., carbon monoxide) may be released in a fire involving benzene. 3. Caution: Benzene will attack some forms ofplastics, coatings, and rubber.
• Flammability I. Flash point: -II.I°C (12°F) (closed cup) 2. Autoignition temperature: 498

# oc (928°F) 

### 3. Flammable limits in air, % by volume: Lower, 1.4; upper, 7.1 4. Extinguishant: Alcohol foam, carbon dioxide, and dry chemical extinguishants are effective. Water may be an ineffective extinguishant but may be used to cool fire-exposed containers. 5. Class IB Flammable Liquid (29 CFR 1910.106), Flammability Rating 3 (NFPA) 6. Unusual fire and explosion hazards: Benzene liquid is flammable, and its vapors can easily form explosive mixtures. Flashbacks may occur along a vapor trail.


### • Warning properties I. Odor threshold: 12 ppm 2. Eye irritation levels: 3,000 ppm for 0.5-1 hour 3. Other information: 3,000 ppm may irritate nose and respiratory tract. 4. Evaluation ofwarning properties for respirator selection: Warning properties are not considered in recommending respirators for use with carcinogens. 

### EXPOSURE LIMITS
The current Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) for benzene is I part ofbenzene per million parts ofair (PPM) as a time-weighted average (TWA) concentration over an 8-hour workshift; the short-termexposure limit is 5 ppm in any 15-minute sampling period. The National Institute for Occupational Safety and Health (NIOSH) recommendsthatbenzene be controlled and handled as a potential humancarcinogen in the workplace and that exposure be reduced to the lowest feasible limit. The NIOSH recommended exposure limit (REL) is 0.1 ppm [0.32 milligrams ofbenzene per cubic meter ofair (mg/m3)] as an 8-hour TWA and I ppm (3.2 mg/m3) as a ceiling in any 15-minute sampling period. The NIOSH REL is the lowest con

### U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES Public Health Service Centers for Disease Control National Institute for Occupational Safety and Health Division of Standards Development and Technology Transfer



### 1988 Benzene 1centration detectable by current NIOSH-validated sampling and analytical methods. The American ConferenceofGovernmental Industrial Hygienists (ACGIH) has designated benzene
as an A2 substance (suspected human carcinogen) having an assigned threshold limitvalue (TLV"') of 10 ppm (30 mg/m3) as a TWA for a normal 8-hour workday and a 40-hour workweek.



## Table 1.-0ccupationalexposure limits for benzene

OSHA PEL TWA



### Short-term exposure limit (15 min) NIOSH REL (Ca)* TWA

Ceiling (15 min) ACGIH TLV"' TWA (A2)t 

### Exposure limits ppm mglm'

5 0.1 I 10 0.32 3.2 30

* (Ca): NIOSH recommendstreating as a potentialhumancarcinogen. t(A2): Suspected human carcinogen.



### HEALTH HAZARD INFORMATION

• Routes ofexposure Benzene may cause adverse health effects following exposure via inhalation, ingestion, or dermal or eye contact. 

### • Summary oftoxicology I. Effects on animals: Acute inhalation ofbenzene by rats, mice, 

### or rabbits caused narcosis, spontaneous heart contractions (ventricular fibrillation), and death due to respiratory paraly

### sis. Subchronic inhalation of benzene by 

### rats produced decreased white blood cell counts, decreased bonemarrow cell activity, increased redbloodcell activity, and cataracts. In rats, chronic inhalation ororal administration ofbenzeneproduced cancers ofthe liver, mouth, and Zymbal gland. Inhalation of benzene by pregnant rats caused retardation offetal development and increased fetal mortality. 2. 

### Effects on humans: Acute inhalation exposure ofbenzene has caused nerve inflammation (polyneuritis), central nervous system depression, and cardiac sensitization. Chronicexposure tobenzene has produced anorexia and irreversibleinjury tothe blood-forming organs; effects include aplastic anemia and leukemia.


### • Signs and symptoms ofexposure 1. 

### Short-term (acute): Exposure to benzene can cause dizziness, euphoria, giddiness, headache, nausea, staggeringgait, weakness, drowsiness, respiratory irritation, pulmonaryedemaandpneumonia, gastrointestinal irritation, convulsions, and paralysis. Benzene can also cause irritation to the skin, eyes, and mucous membranes. 2. wng-term (chronic): Exposureto benzenecancause futigue, nervousness, irritability, blurred vision, and labored breath

### 2 Benzene ing. Repeated skin contact can cause redness, blistering, and dry, scaly dermatitis.



### RECOMMENDED MEDICAL PRACTICES

• Medical surveillance program Workers with potential exposures to chemical hazards should be monitored in a systematic programofmedical surveillance intended to prevent orcontrol occupational injury and disease. The program should include education ofemployers and workers about work-related hazards, placement ofworkers injobs that do notjeopardize their safety and health, earliest possibledetection ofadverse health effects, and referral ofworkers for diagnostic confirmation and treatment. The occurrence of disease (a "sentinel health event," SHE) orotherwork-related adverse health effects should prompt immediate evaluation of primary preventive measures (e.g., industrial hygiene monitoring, engineeringcontrols, and personal protectiveequipment). A medical surveillanceprogram is intended to supplement, not replace, such measures. A medical surveillance program should include systematic collection andepidemiologic analysis ofrelevant environmental and biologic monitoring, medical screening, morbidity, and mortality data. This analysis may provide information about the relatedness ofadverse health effects and occupational exposure that cannot be discerned from results in individual workers. Sensitivity, specificity, and predictive values ofbiologic monitoring and medical screeningtests shouldbeevaluated on an industry-wide basis priorto application in any given worker group. Intrinsic to a surveillance program is the dissemination of summary data to those who need to know, including employers, occupational health professionals, potentiallyexposed workers, and regulatory and public health agencies.


### • Preplacement medical evaluation Priorto placing a worker in ajob with a potential for exposure to benzene, the physician should evaluate and document the worker's baselinehealth status with thorough medical, environmental, and occupational histories, a physical examination, and physiologic and laboratory tests appropriate for the anticipated occupational risks. These shouldconcentrate on the function and integrity of the eyes, skin, liver, and respiratory, nervous, andhematopoietic (blood-cell-forming) systems. The physician should obtain baseline values for the completeblood count and a stained differential count ofall blood cell types. Medical surveillance for respiratory disease shouldbeconducted by using the principles and methods recommended by NIOSH and the American Thoracic Society (ATS). A preplacement medical evaluation is recommended in order to detect and assess preexisting orconcurrentconditions which may be aggravated or result in increased risk when a worker is exposed to benzene at or below the NIOSH REL. The examining physician shouldconsiderthe probable frequency, intensity, and duration of exposure, as well as the nature and degree ofthe condition, in placing such a worker. Such conditions, which should not be regarded as absolute contraindi

### 1988cations to job placement, include a history of chronic skin 

### disease, concurrentdermatitis, ormild non-hemolytic anemia (e.g., mild iron-deficiency anemia).


### • Periodic medical screening and/or biologic monitoring Occupational health interviews and physical examinations should beperformed atregular intervals. Additional examinations may 

### be necessary should a worker report symptomsthat may be attributed to exposure to benzene. The interviews, examinations, and appropriate medical screening and/orbiologic monitoring tests should be directed at identifying an excessive decrease oradverse trend in the integrity and physiologic func

### tion of the skin, liver, and respiratory, nervous, and hematopoietic (blood-cell-forming) systems as compared to the 

### baseline status ofthe individual worker orto expected values for a suitable reference population. The following tests should be used and interpreted according to standardizedprocedures and evaluation criteriarecommendedby NIOSH and the ATS: 

### standardized questionnaires and tests of lung function.


### • Medical practices recommendedatthetimeof jobtrans

### fer or termination. The medical, environmental, and occupational history interviews, the physical examination, and selected physiologic and laboratory tests which were conducted atthe timeofplacement should be repeated at the time ofjob transfer or termination. Any changes in the worker'shealth status shouldbe compared tothose expected for a suitable reference population. Because 

### occupational exposure to benzene may cause diseases of prolonged induction-latency, the need for medical surveillance may extend well beyond termination of employment.


### • Sentinel health events 1. Acute SHE's include: Acute myeloid leukemia and contact 

### and/or allergic dermatitis. 

### 2. Delayed-onset SHE'sinclude: Decrease in the number (neutropenia) or absence (agranulocytosis) ofcertain white blood 

### cells in the peripheral circulation and/or in the bone marrow (aplastic anemia) and cancer ofthe red blood cells (erythroleukemia). 

### MONITORING AND MEASUREMENT PROCEDURES

• TWA 

### exposure evaluation Measurements to determine worker exposure to benzene shouldbe taken sothatthe TWA exposure is based on a single 

### entire workshift sampleoran appropriate number ofconsecutive samplescollectedduring the entire workshift. Undercer

### tain conditions, it may be appropriate to collect several short-term interval samples (up to 30 minutes each) to determine the average exposure level. Air samples should betaken 

### in the worker's breathing zone (airthat most nearly represents that inhaled by the worker).


### • Ceiling concentration evaluation Measurementsto determine workerexposure shouldbe taken duringperiodsofmaximum expected airborneconcentrations ofbenzene. Each measurementto determine the NIOSH REL (ceiling exposure) in theworker'sbreathing zone (airthat most nearly represents that inhaled 

### by the worker) should consist 

### of a 15-minute sample. A minimum ofthree measurements



### 1988 should be taken during one workshift, and the highest of all 

### measurements taken is an estimate ofthe worker's exposure. If

### the periods ofmaximum exposure are not clearly defined,
a statistical procedure which can be used as a peak exposure detection strategy is given in the OccupationalExposure Sampling Strategy Manual.


### • Method Sampling and analysis may be performed by collecting benzene vapors with charcoal tubes followed by desorption with carbon disulfide and analysis by gaschromatography. Direct

### reading devices calibratedto measure benzene may also 

### be used ifavailable. A detailed sampling and analytical method for benzene may be found in the N/OSHManual of AnalyticalMethods (method number 1500). 

### PERSONAL PROTECTIVE EQUIPMENT
Chemical protective clothing (CPC) should be selected after 

### utilizing available performance data, consulting with the manufucturer, and then evaluating the clothing under actual use 

### conditions. Workers should be provided with and required to use CPC, 

### gloves, and other appropriate protective clothing necessary to prevent skin contact with benzene. 

### SANITATION Clothing which is contaminated with benzene should be removed immediately and placed in sealed containers for storage 

### until it can be discarded or until provision is made for the removal ofbenzene from the clothing. Ifthe clothing is to be 

### laundered or cleaned, the person performing the operation should be informed ofbenzene's hazardous properties. Reusable clothing and equipment should be checked for residual 

### contamination before reuse or storage. A change room with showers, washing facilities, and lockers that permit separation of street and work clothes should be provided. Workers should be required to shower following a workshift and priorto putting on streetclothes. Clean workclothes should be provided daily. Skin that becomes contaminated with benzene should be promptly washed with soap and water. Workers whohandle benzene should wash their fuces, hands, and forearms thoroughly with soap and water before eating, 

### smoking, or using toilet facilities. The storage, preparation, dispensing, orconsumption offood or beverages, the storage or application of cosmetics, the storage or use ofsmoking materials, orthe storage or use of products for chewing should be prohibited in work areas. 

### COMMON OPERATIONS AND CONTROLS
Common operations in which exposure to benzene may occur and control methods which may be effective in each case are listed in Table 2.



### Benzene 3

## Table 2.-0perations and methods of control for benzene Operations Duringthe manufacture and processing ofbenzene; during use as a raw material in 

### the production of aromatic compounds and derivatives Duringthe use ofchemicals in which benzene may be an impurity (e.g., naphthas, toluene, xylene) Duringthe manufacture and use ofmotor fuel blends in which benzene is used as an ingredient; during use as an extracting solvent During the preparation and 

### use of paint and varnish removers, rubber cements, 

### and lacquers Controls Process enclosure, local ex

### haust ventilation, personal protective equipment

Process enclosure, local ex

### haust ventilation, personal protective equipment

Process enclosure (when possible), local exhaust ventilation, personal protective equipment, material substitution


### Process enclosure (when possible), local exhaust ventilation, personal protective equipment, material substitution



### EMERGENCY FIRST AID PROCEDURES

In the eventofan emergency, remove the victim from further exposure, send for medical assistance, and initiate emergency procedures.



### • Eye exposure Wherethereis any possibility ofa worker'seyes beingexposed to benzene, an eye-wash fountain should be provided within the immediate work area for emergency use. 

### Ifbenzene gets into the eyes, flush themimmediately with large amounts ofwater for 15 minutes, lifting the lower and upper lids occasionally. Get medical attention as soon as possible. 

### Contact lenses should not be worn when working with this chemical.

• Skin exposure Wherethere is any possibility ofa worker'sbody being exposed to benzene, fucilities for quick drenching ofthe body should be provided withinthe immediateworkareafor emergency use. 

### Ifbenzene gets onthe skin, wash it immediately with soapand water. Ifbenzenepenetratestheclothing, remove theclothing immediatelyand wash the skinwith soapand water. Get medical attention promptly.



### • Rescue If

### a workerhas been incapacitated, move the affected worker 

### from the hazardous exposure. Put 

### into effect the established emergency rescue procedures. Donotbecomea casualty. Understandthefucility's emergency rescueproceduresand know 

### the locations ofrescue equipment before the need arises.



### 4 Benezene 

### SPILLS AND LEAKS
Workers not wearingprotectiveequipmentandclothing should berestrictedfrom areasofspills orleaks until cleanuphas been completed. 

### Ifbenzene is spilled or leaked, the following steps should he taken: 

### 1. Remove all ignition sources. 2. Ventilate area of spill or leak. 3. For small quantities ofliquids containing benzene, absorb
on paper towels and place in an appropriate container. 4. Large quantities ofliquids containing benzene may he absorbed in vermiculite, dry sand, earth, or a similar material and placed in an appropriate container. 5. Liquids containing benzene may he collected by vacuuming with an appropriate system. Ifa vacuum system is used, there should be no sources ofignition in the vicinity ofthe spill, and flashback prevention devices should be provided.



### WASTE REMOVAL AND DISPOSAL
U.S. Environmental ProtectionAgency, DepartmentofTransportation, and/or state and local regulations shall be followed to assure that removal, transport, and disposal are in accordance with existing regulations.



### RESPIRATORY PROTECTION
It must be stressed that the use of respirators is the least preferred method ofcontrolling worker exposure and should not normally be used as the only means of preventing or minimizing exposure during routine operations. However, there are some exceptions for which respirators may be used tocontrolexposure: whenengineering andworkpracticecontrols are not technically feasible, when engineering controls
arein theprocess ofbeing installed, orduringemergencies and certain maintenance operations including those requiring confined-space entry (Table 3). In additionto respirator selection, a complete respiratory protection program shouldbeinstituted which as a minimumcomplies with the requirements found in the OSHA Safety and Health Standards, 29 CFR 1910.134. A respiratory protection program should include as a minimum an evaluation of the worker's ability to perform the workwhile wearing a respirator, the regular training ofpersonnel, fit testing, periodic environmental monitoring, maintenance, inspection, and cleaning. The implementation ofan adequate respiratory protection program, including selection ofthe correctrespirators, requires that a knowledgeable personbe in charge ofthe program and that the program he evaluated regularly. Only respirators that have been approved by the Mine Safety and Health Administration (MSHA, formerly Mining Enforcement and Safety Administration) and by NIOSH should he used. Remember! Air-purifying respirators will not protect from oxygen-deficient atmospheres.


### 1988

### BIBLIOGRAPHY

• American Conference of Governmental Industrial 

### Hygienists: 

### JLVs® ThresholdLimit 11JluesandBiologicalExposure Indicesfor !9/J7-88, Cincinnati, 1987. • American Industrial Hygiene Association: "Benzene" (rev. 1978), Hygienic Guide Series, Detroit, 1978. • American Lung Association of San Diego and Imperial 

### Counties: "Taking the Occupational History," Annals ofInternal Medicine, 99:641-651, November 1983. • Amoore, J.E., and Hautala, E.: "Odoras a Chemical Safety Factor: Odor Thresholds Compared with Threshold Limit Values and Volatilities for 214Industrial Chemicals in Airand Water Dilution," Journal of Applied Toxicology, 3:272-290, !983. • Baier, E.J., Deputy Director, National Institute for Occupational Safety and Health, Center for Disease Control, Public Health Service, Department of Health, Education, and Welfare: StatementbeforetheDepartmentof Labor, Occupation

### al Safety and Health, Public Hearing on the Occupational Standardfor Benzene, July 25-26, 1977. • Clayton, G.D., and Clayton, 

### F.E. (eds.): Toxicology, Vol. liB ofPatty's IndustrialHygiene and Toxicology(3rd rev. ed.),John Wiley & 

### Sons, Inc., New York, 1981. • Code of FederalRegulations, U.S. Department ofLabor, Occupational Safety and Health Administration, 29 CFR 1910.106, 1910.134, 1910.1000, OSHA 2206, revised July I, 1986. • Code of FederalRegulations, U.S. DepartmentofTransportation, 49 CFR 172.101, Transportation49, revised October I. 

### 1982. • Goldman, R.H., and Peters, J.M.: "The Occupational and Environmental Health History," Journal of theAmericanMedicalAssociation, 246:2831-2836, 1981. • Halperin, W.E., Ratcliffe, J., Frazier, T.M., Wilson, L., 

### Becker, S.P., and Shulte, P.A.: "Medical Screening in the Workplace: Proposed Principles," Journal ofOccupational Medicine, 28(8):547-552, 1986.
• Hankinson, J.L.: "Pulmonary Function Testing in the Screening of Workers: Guidelines for Instrumentation, Performance, and Interpretation,''

### JourtUJ! of OccupationalMedicine, 28(10):1081-1092, 1986. • Hawley, G.G.: The Condensed Chemical Dictionary (lOth ed.), Litton Educational Publishing Inc., New York, 1981. • International Agency for Research on Cancer: !ARCMonographs on the Evaluation of the CarcinogenicRiskofChemicals to Humans, Some Industrial ChemicalsandDyestuffs, Vol. 29, Lyon, France, 1982. • Leidei, N.A., Busch, K.A., and Lynch, J.R.: Occupational Exposure Sampling Strategy Manual, U.S. Department of



### 1988 Health, Education, and Welfare, Public Health Service, Center for Disease Control, National Institute for Occupational Safety and Health, DHEW (NIOSH) Publication No. 77-173, Cincinnati, 1977. • Levy, B.S., and Wegman, 

### D.H. (eds.): OccupationalHealth: Recognizing and Preventing l!Vrk-Related Disease, Little, Brown and Company, Boston, 1983. • National Fire Protection Association: 

### NationalFire Codes®, (Vol. 13), Quincy, Massachusetts, 1983. • National Institute for Occupational Safety and Health, U.S. DepartmentofHealth, Education, and Welfare, Public Health Service, Center for Disease Control: 

### Criteriafor a Recommended Standard
....Occupational Exposure to Benzene, HSM (NIOSH) Publication No. 74-137, Cincinnati, 1974. • National Institute for Occupational Safety and Health, U.S. DepartmentofHealth, Education, and Welfare, Public Health Service, Center for Disease Control: RevisedRecommenda

### tionforan OccupationalExposure Standard for Benzene, Cincinnati, 1976. • National Institute for Occupational Safety and Health, U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control: N/OSHManual ofAnalytical Methods (3rd ed., Vol. 1), Eller, P.M. (ed.), DHHS (NIOSH) Publication No. 84-100, Cincinnati, 1984. • National Institute for Occupational Safety and Health, U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control: 

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ChemicalSubstances (Microfiche Edition). Sweet, D.V., and Lewis, R.J. (eds.), Cincinnati, April 1985.
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### National Affairs, Washington, DC, 1984. • Rutstein, D.D., Mullan, R.J., Frazier, T.M., Halperin. W.E., Melius, J.M., and Sestito, J.P.: "Sentinel Health Events (Occupational): A Basis for Physician Recognition and Public Health Surveillance," AmericanJournalof Public Health, 

### 73:1054-1062, 1983. • Sax, N.l. (ed.): Dangerous PropeniesoflndustrialMaterials (6th ed.), Van Nostrand Reinhold Company, New York, 1984. • U.S. Department ofTransportation, Coast Guard: CHRIS Hazardous Chemical Data, GPO Stock No. 050-012-00147-2. 1978. • Weast, R.C. (ed.): CRC Handbook of Chemistry andPhysics (64th ed.), CRC Press, Inc., Boca Raton, Florida, 1983. • Windholz. M. (ed.): The Merck Index (lOth ed.), Merck & 

### Co., Inc., Rahway, New Jersey, 1983.



### Benzene 5

## Thble 3.-Respiratory protection for benzene Condition Minimum respiratory protection• Any detectable concentration Any self-containedbreathingapparatus with a full facepiece and operated in a pressure-demand 

### or other positive pressure mode

Planned or emergency entry into environments containing unknown or any detectable 

### concentration

Firefighting

Escape only Any supplied-air respirator with a full facepiece and operated in a pressure-demand or other positivepressure mode in combinationwith anauxiliary self-containedbreathingapparatus operated in a pressure-demand or other positive pressure mode Any self-containedbreathingapparatus with a full facepiece and operated in a pressure-demand 

### or other positive pressure mode Any supplied-air respirator with a full facepiece and operated in a pressure-demand or other positivepressure mode in combinationwith an auxiliary self-containedbreathing apparatus operated in a pressure-demand or other positive pressure mode Any self-containedbreathing apparatus with a full facepiece and operated in a pressure-demand
or other positive pressure mode Any air-purifying full facepiece respirator (gas mask) with a chin-styleorfront- orback-mounted 

### organic canister Any appropriate escape-type self-contained breathing apparatus 

## * Only NIOSH/MSHA-approved equipment should be used.



### 6 Benzene 1988