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Chemical Fact Sheet

Chemical Abstract Number (CAS #) 71432
CASRN 71-43-2
SynonymsBenzene
Cyclohexatriene
Benzol
Analytical Methods EPA Method 502.2
EPA Method 503.1
EPA Method 524.2
EPA Method 602
EPA Method 624
EPA Method 8021
EPA Method 8260
Molecular FormulaC6H6

Link to the National Library of Medicine's Hazardous Substances
Database for more details on this compound.

Use MFR MEDICINAL CHEM, DYES, ORG CMPD, ARTIFICIAL LEATHER, LINOLEUM, OIL CLOTH, VARNISHES, LACQUERS; SOLVENT FOR WAXES, RESINS, OILS USE AS SOLVENT IS NOW DISCOURAGED Used for printing & lithography, paint, rubber, dry cleaning, adhesives & coatings, detergents Extraction and rectification; preparation and use of inks in the graphic arts industries; as a thinner for paints; as a degreasing agent CHEM INT FOR ETHYLBENZENE, CUMENE, CYCLOHEXANE, NITROBENZENE, MALEIC ANHYDRIDE, CHLOROBENZENES, DETERGENT ALKYLATE, ANTHRAQUINONE, BENZENE HEXACHLORIDE, BENZENE SULFONIC ACID, BIPHENYL, HYDROQUINONE, & RESORCINOL /Benzol for pesticidal uses has been cancelled. It was in use alone or in formulations for screwworm control on animals. It was an ingredient of some early grain fumigants In the tire industry (McMichael et al, 1975), & in shoe factories (Aksoy et al, 1974), benzene is used extensively. Used primarily as a raw material in the synthesis of styrene (polystyrene plastics and synthetic rubber), phenol (phenolic resins), cyclohexane (nylon), aniline, maleic anhydride (polyester resins), alkylbenzenes (detergents), chlorobenzenes, and other products used in the production of drugs, dyes, insecticides, and plastics.
Consumption Patterns Consumption by chemical industry in USA, 1977: 1.4 billion gallons annually. CHEM INT FOR ETHYLBENZENE, 49.1%; CHEM INT FOR CUMENE, 18.4%; CHEM INT FOR CYCLOHEXANE, 15.1%; CHEM INT FOR NITROBENZENE, 4.5%; CHEM INT FOR MALEIC ANHYDRIDE, 2.8%; CHEM INT FOR CHLOROBENZENES, 2.5%; CHEM INT FOR DETERGENT ALKYLATE, 2.4%; EXPORTS, 2.7%; OTHER USES, 2.5% (1981 NON-GASOLINE USES) Demand: (1980) 1,586 Million Gal; Projected demand for (1984): 1,708 Million Gal BENZENE RANKED 17TH IN 1981 & 1982 IN THE TOP 50 CHEMICAL PRODUCTION: BILLIONS OF LB: 7.87 (1982), 9.61 (1981). Ethylbenzene/styrene, 52%; cumene/phenol, 22%; clyclohexane, 15%; nitrobenzene/aniline, 4.5%; detergent alkylate, 2.5%; chlorobenzenes, maleic anhydride and other, 3%; exports, 1% (1984) USA benzene demand is projected to climb from 3.8% in 1987, to 5.7 million tons, and reach 6 million tons in 1990 (1987 and 1990) In future, coal will increasingly replace petroleum & natural gas as a source of hydrocarbons both for fuel & petrochemicals. Processes such as USA Steel Corporation's Clean Coke process, which yields 38% coke & 20% chemical by-products compared to 73% coke & 2% chemical by-products in conventional coking technology, should soon be used commercially. New coking, liquefaction, & gasification processes for coal are all potential sources of benzene. CHEMICAL PROFILE: Benzene. Ethylbenzene/styrene, 55%; cumene/phenol, 21%; cyclohexane, 14%; nitrobenzene/aniline, 5%; detergent alkylate, 3%; chlorobenzenes, exports and others, 2%. CHEMICAL PROFILE: Benzene. Demand: 1986: 1,603 million gal; 1987: 1,667 million gal; 1991 projected/: 1,790 million gal. (Includes imports; 155 million gal were imported in 1986.)
Apparent Color CLEAR, COLORLESS LIQ ; RHOMBIC PRISMS
Odor AROMATIC ODOR
Boiling Point 80.1 DEG C
Melting Point 5.5 DEG C
Molecular Weight 78.11
Density 0.8787 AT 15 DEG C/4 DEG C
Odor Threshold Concentration BENZENE HAS DISTINCTIVE SRP: AROMATIC ODOR HOWEVER /WARNING PROPERTIES ARE INADEQUATE SINCE 100 PPM HAS IRRITATION RATING OF 0 & ODOR INTENSITY BETWEEN 1 & 2. 4.68 PPM In air: 4.9 mg/cu m (characteristic odor), in water: 2.0 mg/l.
Sensitivity Data Benzene is irritant to skin
Environmental Impact Benzene will enter the atmosphere primarily from fugitive emissions and exhaust connected with its use in gasoline. Another important source is emissions associated with its production and use as an industrial intermediate. In addition, there are discharges into water from industrial effluents and losses during spills. If benzene is released to soil, it will be subject to rapid volatilization near the surface and that which does not evaporate will be highly to very highly mobile in the soil and may leach to groundwater. It may be subject to biodegradation based on reported biodegradation of 24% and 47% of the initial 20 ppm benzene in a base-rich para-brownish soil in 1 and 10 weeks, respectively. It may be subject to biodegradation in shallow, aerobic groundwaters, but probably not under anaerobic conditions. If benzene is released to water, it will be subject to rapid volatilization; the half-life for evaporation in a wind-wave tank with a moderate wind speed of 7.09 m/sec was 5.23 hrs; the estimated half-life for volatilization of benzene from a model river one meter deep flowing 1 m/sec with a wind velocity of 3 m/sec is estimated to be 2.7 hrs at 20 deg C. It will not be expected to significantly adsorb to sediment, bioconcentrate in aquatic organisms or hydrolyze. It may be subject to biodegradation based on a reported biodegradation half-life of 16 days in an aerobic river die-away test. In a marine ecosystem biodegradation occurred in 2 days after an acclimation period of 2 days and 2 weeks in the summer and spring, respectively, whereas no degradation occurred in winter. According to one experiment, benzene has a half-life of 17 days due to photodegradation which could contribute to benzene's removal in situations of cold water, poor nutrients, or other conditions less conductive to microbial degradation. If benzene is released to the atmosphere, it will exist predominantly in the vapor phase. Gas-phase benzene will not be subject to direct photolysis but it will react with photochemically produced hydroxyl radicals with a half-life of 13.4 days calculated using an experimental rate constant for the reaction. The reaction time in polluted atmospheres which contain nitrogen oxides or sulfur dioxide is accelerated with the half-life being reported as 4-6 hours. Products of photooxidation include phenol, nitrophenols, nitrobenzene, formic acid, and peroxyacetyl nitrate. Benzene is fairly soluble in water and is removed from the atmosphere in rain. The primary routes of exposure are inhalation of contaminated air, especially in areas with high traffic, and in the vicinity of gasoline service stations and consumption of contaminated drinking water.
Environmental Fate TERRESTRIAL FATE: If benzene is released to soil it will be subject to rapid volatilization near the surface. That which does not evaporate will be highly to very highly mobile in soil and may leach to groundwater. The effective half-lives for volatilization without water evaporation from soil to benzene uniformly distributed to 1 and 10 cm in soil were 7.2 and 38.4 days, respectively . It may be subject to biodegradation based on reported biodegradation of 24% and 47% of the initial 20 ppm benzene in a based-rich para-brownish soil in 1 and 10 weeks, respectively . It may be subject to biodegradation in shallow, aerobic groundwaters, but probably not under anaerobic conditions. AQUATIC FATE: If benzene is released to water, it will be subject to rapid volatilization; the half-life for evaporation in a wind-wave tank with a wind speed of 7.09 m/sec was 5.23 hrs ; the estimated half-life for volatilization of benzene from a model river one meter deep flowing 1 m/sec with a wind velocity of 3 m/sec is estimated to be 2.7 hrs at 20 deg C. It will not be expected to significantly adsorb to sediment, bioconcentrate in aquatic organisms or hydrolyze. It may be subject to biodegradation based on a reported biodegradation half-life of 16 days in an aerobic river die-away test . In a marine ecosystem, biodegradation occurred in 2 days after an acclimation period of 2 days and 2 weeks in the summer and spring, respectively, whereas no degradation occurred in winter . AQUATIC FATE: Evaporation was the primary loss mechanism in winter in a mesocosm experiment which simulated a northern bay where the half-life was 13 days . In spring and summer the half-lives were 23 and 3.1 days, respectively . In these cases biodegradation plays a major role and takes about 2 days . However, acclimation is critical and this takes much longer in the colder water in spring . According to one experiment, benzene has a half-life of 17 days due to photegradation which could contribute to benzene's removal. In situations of cold water, poor nutrients, or other conditions less conducive to microbial, photolysis will play a important role in degradation. ATMOSPHERIC FATE: If benzene is released to the atmosphere, it will exist predominantly in the vapor phase . Gas-phase benzene will not be subject to direct photolysis but it will react with photochemically produced hydroxyl radicals with a half-life of 13.4 days calculated using an experimental rate constant for the reaction. The reaction time in polluted atmospheres which contain nitrogen oxides or sulfur dioxide is accelerated with the half-life being reported as 4-6 hours . Products of photooxidation include phenol, nitrophenols, nitrobenzene, formic acid, and peroxyacetyl nitrate. Benzene is fairly soluble in water and is removed from the atmosphere in rain .
Drinking Water Impact DRINKING WATER: 113 public supplies, 1976, 7 sites pos, avg of positive sites <0.2 ppb . 5 USA cities, 1974-5, 0-0.3 ppb . Contaminated drinking water wells in NY, NJ, CT, 30-300 ppb; highest concn in drinking water from surface source, 4.4 ppb . 3 surveys of community water supplies: 0 of 111 pos; 7 of 113 pos, mean 4 ppb; 4 of 16 pos (0.95 ppb-max) . USA Groundwater Supply Survey (GWS, 1982, finished drinking water), 466 samples selected at random from 1000 in survey, 0.6% pos, 3 ppb median, 15 ppb max . Wisconsin drinking water wells, data through Jun 1984, 1174 community wells, 0.34% pos, 617 private wells, 2.9% pos(6). GROUNDWATER: Chalk Aquifer (UK), 210 m from petrol storage, 1-10 ppb; Chalk Aquifer (UK), 120 m from petrol storage, >250 ppb; Chalk Aquifer (UK), 10 m from petrol storage, 1250 ppb; distances refer to benzene movement in groundwater . SURFACE WATER: 14 heavily industrialized with basins, 1975-1976, 20% samples >1 ppb and between 1 and 7 ppb . Lake Erie, 1975-6, 0-1 ppb, 1 of 2 sites positive; Lake Michigan, 1975-6, 0-7 ppb, 5 of 7 sites positive . 700 random sites in US, 1975, 5.4 ppb avg . US EPA STORET database, 1,271 samples, 15.0% pos, 5.0 ppb median . SEAWATER: 5-15 parts per trillion Gulf of Mexico, 1977, unpolluted areas; 5-175 parts per trillion, Gulf of Mexico, 1977, anthropogenic influence . RAIN/SNOW: Detected in rainwater in Japan and in the UK (87.2 ppb)(1,2). Benzene occurs in both ground water and surface public water supplies with higher levels occurring in ground water supplies. Based upon Federal drinking water surveys, approximately 1.3% of all ground water systems are estimated to contain benzene at levels greater than 0.5 ug/l. The highest level reported in the surveys for ground water was 80 ug/l. Approximately 3% of all surface water system are estimated to be contaminated at levels higher than 0.5 ug/l. None of the systems are expected to contain levels higher than 5 ug/l. EFFL: Wastewater from coal preparation plants, 0.3-48 ppb ; wastewater from plants which manufacture or use benzene <1-179 parts per trillion ; stack emissions from coking plants (Czechoslovakia), 15-50 ppm ; stack emission estimates from chemical plants using emissions and worst case modeling at 150 m from source, less than or equal to 5 ppm . Groundwater at 178 CERCLA hazardous waste sites, 11.2% pos . US EPA STORET database, 1,474 samples, 16.4% pos, 2.50 ppb median . Industries in which mean or max levels in raw wastewater exceeded 1 ppm are (number of samples, percent pos, mean, max, in ppm): raw wastewater: auto and other laundries (20 samples, 70% pos, <1.4 ppm mean, 23 ppm max), iron and steal manufacturing (mfg) (9 samples, 77.8% pos, <8.0 mean, 46 max), aluminum forming (32 samples, 56.2% pos, 0.70 mean, 2.1 max), photographic equipment/supplies (48 samples, 54.2% pos, 0.16 mean, 2.1 max), pharmaceutical mfg (9 samples, 100% pos, 12 mean, 87 max), organic chemical/plastics mfg (number of samples not reported (NR), 63 detections, 22, NR), paint and ink formulation (36 samples, 63.9% pos, 1.2 mean, 9.9 max), petroleum refining (11 samples, number of pos NR, <0.10, 2.4), rubber processing (4 samples, 100% pos, 0.60 mean, 3.4 max), timber products processing (14 samples, 92.9% pos, 0.2 mean, 2.8 max); treated wastewater: auto and other laundries (4 samples, 50% pos, 0.1 ppm mean, 0.2 ppm max), iron and steal manufacturing (mfg) (13 samples, 76.9% pos, <14 mean, 120 max), aluminum forming (21 samples, 81.0% pos, <0.0058 mean, 0.040 max), photographic equipment/supplies (4 samples, 100% pos, 0.016 mean, 0.021 max), pharmaceutical mfg (6 samples, 100% pos, 1.8 mean, 10 max), organic chemical/plastics mfg (number of samples not reported (NR), 42 detections, 26, max NR), paint and ink formulation (24 samples, 62.5% pos, 0.39 mean, 3.8 max), petroleum refining (13 samples, NR, NR, 0.012), rubber processing (5 samples, 100% pos, <0.0077 mean, 0.010 max), timber products processing (5 samples, 60% pos, 0.010 mean, 0.033 max) . Industrial sources of wastewater pollution from benzene in ug/l (avg; range): coal mining (2.6; 0-15), textile mills (<5; 0-200), timber products processing (350; 0-2,800), petroleum refining (>100; ND), paint and ink formulation (1,200; 0-9,900), gum and wood chemicals (180; 0-710), rubber processing (610; 0-3,400), auto and other laundries (840; 0-23,000), pharmaceuticals (220; 0-2,100), ore mining and dressing (2.1; 0-4.2), steam electric power (45, ND), foundries (200; ND), leather tanning and finishing (19; 0-150), nonferrous metals (11; 0-160), iron and steel (2,000; 0-43,000). From table

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