Potential uses of petrochemical products can result in significant benzene exposures: MSDSs must list benzene as an ingredient.

According to 29 CFR1910.1200 (Hazard Communication Standard [HCS]), a material safety data sheet (MSDS) must list a carcinogen as an ingredient if its concentration in a product is 0.1% or more by weight. However, according to the HCS, when the concentration of a carcinogen in a product is less than 0.1% (by weight) it may not be necessary to list it as an ingredient on the MSDS. The standard stipulates that if potential uses of the product can result in exposures to the carcinogen that exceed the Occupational Safety and Health Administration (OSHA) permissible exposure limit or the ACGIH threshold limit value (TLV), then it must be listed. This article focuses on the failure of MSDSs to report benzene as a listed ingredient in products that incorporate petroleum-derived ingredients such as toluene and hexane. In the United States, approximately 238,000 people are occupationally exposed to benzene each year. Only rarely is benzene listed as an ingredient on MSDSs even though it often comprises more than 0.1% of petroleum solvents and, when its concentrations in petroleum-derived products are much less than 0.1%, inhalation exposures to benzene can be much higher that its OSHA PEL of one part per million (ppm) by volume (v/v) andACGIH TLV of/one-half ppm (v/v). As a consequence of benzene's omission from MSDSs as a listed ingredient, employers are frequently unaware of their requirement to implement 29 CFR 1910.1028 (Benzene Standard) and of the need to address employee exposures to benzene in the workplace. This article demonstrates that benzene should be listed as an ingredient on MSDSs, even at concentrations in benzene-containing products that are between one and two orders of magnitude below OSHA's 0.1% threshold. An exposure assessment methodology is presented that is applicable to employees whose conditions of exposure are similar to those in the published study. These workers make up a similar exposure group. The information and methodology presented here are germane to preparation of accurate MSDSs for benzene-containing products, employers who must comply with 29 CFR 1910.1028, and retrospectively estimating exposures to benzene.

An overview of occupational benzene exposures and occupational exposure limits in Europe and North America.

Benzene has become one of the most intensely regulated substances in the world. Its ubiquitous use as a solvent has led to many working populations being exposed; in the early days often in uncontrolled conditions, leading to high exposures. Current occupational exposures are tightly controlled and are largely confined to workers in the petrochemical industry, vehicle mechanics, firefighters, workers exposed to automobile emissions, and some other occupational groups. Typically, occupational exposure levels are currently at or below 3.25 mg/m3 (1 ppm), and environmental exposures are typically below 50 microg/m3 (15 ppb). Smoking remains a significant source of exposure in both occupationally and non-occupationally exposed individuals. The early experiences of high occupational exposures led to the identification of haematopoietic effects of benzene and the need for improved control and regulation. As with most occupational standards, there has been a reduction in exposure limits as effects have been identified at ever-lower levels, accompanied by a societal concern for improved standards of occupational health. In 1946, the United States occupational exposure limit for benzene, promulgated by the American Conference of Governmental Industrial Hygienists, was 325 mg/m3 (100 ppm), but nowadays most European and North American countries have harmonised at 1.63-3.25mg/m3 (0.5-1 ppm). This latter figure was agreed within the European Union in 1997 and was adopted within national legislation by all Member States. The data on which this limit is set are essentially the same as those used by other standard-setting committees; this is an excellent example of how standards are set using science, pragmatism and societal values in the absence of complete information.