Benzene permissible exposure levels

Chronic Health Effect A chronic health effect is an adverse health effect resulting from long-term exposure to a substance. The effects could be a skin rash, bronchitis, cancer, or any other medical condition. An example would be liver cancer from inhaling low levels of benzene at your workplace over several years. The term is also applied to a persistent (months, years, or permanent) adverse health effect resulting from a short-term (acute) exposure. Chronic effects from long-term exposure to chemicals are fairly common. Recognize the PEL (permissible exposure level) for each substance in your workplace and minimize your exposure whenever possible. 

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. 

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... 

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. 

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... 

BTX processing has come under steadily increasing pressure to reduce emissions and workplace exposures (see Industrial hygiene). Reductions in the permissible levels of both benzene and total aromatics (BTX) in gasoline have been legislated. Whereas all BTX components ate to be controUed, the main focus is on benzene because it is considerably mote toxic than the others and is classified as a known carcinogen (42). 

EPA has set the maximum permissible level of benzene in drinking water at 5 parts per billion (ppb). Because benzene can cause leukemia, EPA has set a goal of 0 ppb for benzene in drinking water and in water such as rivers and lakes. EPA estimates that 10 ppb benzene in drinking water that is consumed regularly or exposure to 0.4 ppb benzene in air over a lifetime could cause a risk of one additional cancer case for every 100,000 exposed persons. EPA recommends a maximum permissible level of benzene in water of 200 ppb for short-term exposures (10 days) for children. 

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. ... 

Benzene Mukhametova and Vozovaya within or lower than the maximum permissible levels no reasonable chance for exposure to some daily exposures may be expected between 10-50% OEL TLV-TWA 10 ppm... 

Figure 20.5.2. Extrapolations of levels of exposure to benzene. [Adapted, by permission, from R.A. Rinsky, New England J. Med., 1987.]...

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