Benzene, OSHA exposure level

Benzene can have both chronic and acute toxic effects. The risk of acute effects is low, since acute symptoms occur only at 1000 ppm or higher. Chronic vapor inhalation at the level of 25 to 50 ppm can cause changes in blood chemistry, and co/ rmoa7 exposure at 100 ppm can cause severe blood disorders. The OSHA exposure limits for benzene vapor are 1 ppm as an 8-hour time-weighted average and a ceiling of 50 ppm for no more than 10 min. In order to reach the level of 10 ppm in a laboratory of 750 m volume, 23 g of liquid benzene would have to evaporate into a closed atmosphere. Thus the hazards associated with the infrequent use of liquid benzene in a well-ventilated laboratory are very low. 

OSHA has in the past decade completed a number of rulemakings on occupational carcinogens, including arsenic, benzene, asbestos, ethylene oxide and acrylonitrile. The agency conducted risk assessments and concluded that occupational exposure standards - so-called Permissible Exposure Levels, PELs - were too high and had to be reduced. 

Effective Dec. 10, 1987, the existing standard for benzene was amended under OSHA (29 CER, Part 1910.1028). The revised standard reduced the permissible exposure limit from 10 ppm (32 mg/m ) to 1 ppm (3.2 mg/m ) iu an 8-h TWA. The short term exposure limit (STEL) of 5 ppm was set over a 15 min period. The standard also established action level requirements for exposure over 0.5 ppm. 

Exposure limits The U.S. EPA has set the maximum permissible level of benzene in drinking water at 5 ppb of water. OSHA has set limits of 1 ppm of workplace air for 8 hours (TWA). NIOSH recommends that the benzene be treated as a potential human carcinogen and that the exposure limit be regulated as a potential human carcinogen. ... 

Courts have enforced the distinction between regulatory programs that permit (or require) risk assessment from those which prohibit reliance on risk assessment. In the seminal 1980 case reviewing the benzene standard promulgated by the U.S. Occupational Safety and Health Administration (OSHA), the U.S. Supreme Court held that the U.S. OSHA must use risk assessment to demonstrate that workers were exposed to a significant risk before taking regulatory action (lUD 1980). The U.S. OSHA had proposed to reduce exposures to the lowest levels feasible after... 

Benzene. Benzene is recognized as the most toxic compound among BTEX, because it has been proved that breathing very high concentrations of benzene in air can cause death and that long-term exposure to lower levels causes leukemia. The Occupational Safety and Health Administration (OSHA) has set a permissible exposure limit of 1 ppm in the workplace during an 8-h day if 40 h a week are worked. 

The final OSHA 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). 

Benzene (CAS 71-43-2) Vapors mildly irritating to eyes and respiratory tract. Well absorbed by all routes. A CNS depressant at high levels. Symptoms include headache, nausea, tremors, cardiac arrhythmias, and coma. Chronic exposure may result in hematopoietic system depression, aplastic anemia, and leukemia (lARC 1). See also p 128. 0.5 ppm, A1,S OSHA CA NIOSH CA 500 ppm ERPG-1 50 ppm ERPG-2 150 ppm ERPG-3 1000 ppm 2 3 0 Coloriess liquid. Aromatic hydrocarbon odor. Vapor pressure is 75 mm Hg at BO C (BS E). Flammable. 

Terminology used by the Occupational Safety and Health Administration (OSHA) and the National Institute for Occupational Safety and Health (NIOSH) to state the level of toxicant that requires medical surveillance and training to further protect employees. It is usually one-half the level of the permissible exposure limit. Action levels exist for only a few air contaminants, such as lead, cadmium, and benzene. Activated Charcoal... 

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