Benzene permissible exposure limits

In 1971 the OSHA standard for benzene (20 CFR, Part 1910.0000) adopted a permissible exposure limit (PEL) of 10 ppm benzene measured as an 8-h TWA. In October of 1976 NIOSH updated its earlier criteria document on benzene and recommended that OSHA lower the benzene exposure standard from 10 to 1 ppm. This proposed implementation was blocked by the United States Supreme Court iu 1980 on the basis of iusufficient evidence linking benzene to cancer deaths. By the mid-1980s convincing evidence of the carciuogenicity of benzene appeared through animal studies which justified reconsideration of the 1 ppm PEL (130). 

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. 

Photocatalytic research has explored benzene destruction [3-7] because of its carcinogenic properties and low permissible exposure limits. However, these properties also impose limits on the industrial use of benzene, so other aromatics, particularly toluene, are used more often and might be present at higher levels in... 

OSHA requires employers of workers who are occupationally exposed to benzene to institute engineering controls and work practices to reduce and maintain employee exposure at or below permissible exposure limits (PEL). If the employer can document that benzene is used in the workplace less than 30 days per year, the employer can use any combination of engineering controls, work practice controls, or respirators to reduce employee exposure to or below the (PEL) of 1 ppm. However, the employer must use... 

Benzene, toluene, ethylbenzene, and xylenes (known as BTEX) are probably the most widely used aromatics, in abimdant use in automotive fuel, as solvents or as feedstock for more complex compounds. The American Occupational and Safety Administration (OSHA) permissible exposure limit for benzene, for example, is as low as 3.26 mg m (Ippm) due to its carcinogenic nature. This value should be compared with the 10-100 Xgm of BTEX typically foimd in urban outdoor environment (Saarela et al., 2003). The photocatalytic degradation of BTEX might emit a variety of intermediate products and by-products. For example, the photocatalytic degradation... 

The odor threshold for benzene is 30 ppm, but the current American Conference of Governmental Industrial Hygienists Threshold Limit Value considered safe for occupational exposure (8 h day) is below that threshold at 0.5 ppm. The Occupational Safety and Health Administration permissible exposure limit (PEL) is 1 ppm, with a short-term exposure limit (STEL) of 5 ppm. The National Institute for Occupational Safety and Health recommends an exposure limit (recommended exposure limit) of 0.1 ppm with a STEL of 1 ppm. 

Occupational Safety and Health Administration (OSHA) has not identified thresholds for carcinogens that will protect 100% of the population. It usually recommends that occupational exposures to carcinogens be limited to the lowest detectable concentration. To ensure maximum protection from carcinogens through the use of respiratory protection, only the most reliable and protective respirators are recommended. The OSHA permissible exposure limit (PEL) for benzene-soluble fraction of coke oven emissions is 0.150 mg m. ... 

The Occupational Safety and Health Administration permissible exposure limit is 100 ppm (435 mg m ) (8h time-weighted average), based on irritation. The National Institute for Occupational Safety and Health short-term exposure limit (15 min exposure limit) is 125 ppm (543mgm ), based on irritation. The odor threshold is 8.7 ppm. Hazardous waste number F003. The acceptable daily intake (US Environmental Protection Agency (EPA)) is 1.6 mg day The EPA oral reference dose (Rfd) for ethyl benzene is 0.1 mg kg day The oral Rfd... 

In 1996, there were 25,000 workers employed in 75-100 domestic wood treatment plants using coal tar creosote. As a result of the use of engineering controls and personal protective equipment (e.g., respiratory protection and impervious gloves) required in the 1986 settlement of the EPA Special Review process,1 airborne exposures to creosote components in the workplace are generally below the OSHA permissible exposure limit (PEL) of 0.2 mg benzene soluble particulates perm3 air (Rivers 1990). 

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 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 analjdical limits of detection or technological feasibility). Also, in 1989, NIOSH adopted several quantitative RELs for carcinogens from OSHA s permissible exposure limit (PEL) update.]... 

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... 

The purpose of this subpart is to protect employees from exposure to toxic and hazardous substances in the workplace. It covers the Permissible Exposure Limits (PEL) for all air contaminants including all gases, vapors, and dusts. Some of the contaminants covered underthis subpart include asbestos, coal tar pitch volatiles, vinyl chloride, inorganic arsenic, lead, cadmium, benzene, coke-oven emissions, bloodborne pathogens, cotton dust, ethylene oxide, and formaldehyde. 

Regulated area means any area where airborne concentrations of benzene exceed or can reasonably be expected to exceed, the permissible exposure limits, either the 8-hour time-weighted average exposure of 1 ppm or the short-term exposure limit of 5 ppm for 15 minutes. 

Benzene has the ability to damage the bone marrow and to cause anemia and leukemia. This hematopoietic toxicity shown by benzene is unique as the myelotoxic effect disappears when one or more alkyl groups are attached to the benzene structure. Toluene and xylene are examples of the aromatic solvents which do not show the hematopoietic toxicity. The OS HA regulation 29 CFR 1910.1028 allows a Permissible Exposure Limit (PEL) of 1.0 ppm benzene in the work area for an 8 hr day and 40 hr work week. The current documents of both the OSHA and ACGIH organizations consider benzene as a suspected human carcinogen. 

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. ... 

Individuals employed in industries that use or make benzene or products containing benzene may be exposed to the highest concentrations of benzene. The National Occupational Exposure Survey (NOES), conducted by NIOSH from 1981 to 1983, estimated that approximately 272,300 workers employed in various professions were potentially exposed to benzene in the United States. Approximately half of these workers were employed in general medical and surgical hospitals, and their occupations included nurses and aides, physicians, technicians, technologists, therapists, dieticians, pharmacists, and janitors (NIOSH 1989). The NOES database does not contain information on the frequency, concentration, or duration of exposure the survey provides only estimates of workers potentially exposed to chemicals in the workplace. The current OSHA permissible limit for an 8-hour TWA exposure to benzene is 1 ppm and a... 

Sherwood RJ. 1988. Pharmacokinetics of benzene in a human after exposure at about the permissible limit. Ann NY Acad Sci 534 635-647. 

Coal Tar Products. In an industrial health survey of employees in a wood preservative plant in which coal tar creosote, coal tar, and pentachlorophenol were the main treatments used, cardiovascular effects, including increased diastolic blood pressure, were noted in 21% (24 of 113) of the employees examined (TOMA 1979). Industrial hygiene surveys of coal tar pitch volatiles at this and three other wood preservative plants indicated that airborne exposure to benzene-soluble components of the coal tar pitch volatiles was within the OSHA permissible limit of 0.2 mg/m3 in 94% of the samples (TOMA 1979). The other 6% of the samples ranged from 0.21 to 3.6 mg/m3 (TOMA 1979). Nevertheless, no clear relationship could be established because exposure routes in addition to inhalation (e.g., oral and dermal) were likely. Also, the ability to relate cardiovascular effects to coal tar creosote and coal tar exposure was further confounded by the possibility that the subjects were also exposed to other chemicals including pentachlorophenol and cigarette smoke (TOMA 1979). Additional limitations of the study are noted above (see "Respiratory Effects"). However, in another industrial study, an increase in mortality from... 

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