The impact of the revision of the threshold of exposure to benzene — Occupational health and safety

The impact of the revision of the benzene exposure threshold

It is estimated that nearly 1.37 million workers are exposed to benzene at work.

The American Conference of Governmental Industrial Hygienists (ACGIH) proposes to reduce the time-weighted average exposure limit value (TLV) for benzene to 0.02 ppm and to reduce the short-term exposure limit (STEL) 15 minutes at 0.1 ppm. So what is known about workers who have been exposed to benzene, and how does this change the paradigm of what is already known? The US National Occupational Exposure Survey (1981-1983) estimated that approximately 272,300 workers (143,000 women) were potentially exposed to benzene in the United States alone. Due to economic growth, technology and industry innovations over the past 40 years, the current exposed population may be closer to 1.37 million workers nationwide.

Sample data collected by OSHA’s Integrated Management Information System (IMIS) shows limited evidence of data across industrial markets. The data collected shows that most workers (94.5%) would be exposed to benzene above the TLV proposed by the ACGIH. Only 2.9% of workers were exposed above the current ACGIH TLV of 0.5 ppm and 1.6% of workers were exposed above the Permissible Exposure Limit (PEL) of OSHA 1 ppm over an eight hour TWA. So why was only limited evidence collected to assess the workforce? Benzene is considered a confirmed human carcinogen by ACGIH, the International Agency for Research on Cancer (IARC), the National Toxicology Program (NTP), and the United States Environmental Protection Agency (EPA). The global cancer burden is high and continues to increase based on epidemiological data. It is clear that all workplaces should be reassessed for benzene vapors to determine occupational exposure if the ACGIH TLV and STEL values ​​are reduced.

Introduction to Benzene

Benzene or benzol is a clear, colorless and highly flammable liquid with a kind of sweet smell. It is an aromatic organic compound with the molecular formula C6H6. The chemical is abundant as a component of motor vehicle exhaust emissions, volcanic or forest fires and is found in gasoline, crude oil and cigarette smoke.

This article originally appeared in the October 1, 2022 issue of Occupational Health and Safety.

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