Revisiting Benzene Exposure in the Shanghai Women’s Health Study
Findings Reinforce Dangers of Occupational Benzene Exposure
Doctors and researchers around the world continue to find evidence linking benzene exposure to the development of non-Hodgkin’s lymphoma (NHL). Agencies including the U.S. Environmental Protection Agency (EPA) and the International Agency for Research on Cancer (IARC) classify benzene as a known human carcinogen.
Researchers supported by the National Institutes of Health and the National Cancer Institute published a 2015 study in the scientific journal Environmental Health Perspectives relating occupational benzene exposure to the development of NHL. That study, “Occupational Exposure to Benzene and Non-Hodgkin Lymphoma in a Population-Based Cohort: The Shanghai Women’s Health Study (Bassig),” examines the health outcomes of benzene-exposed women.
Those same researchers further commented on their findings in 2017 with “Evaluating Exposure-Response Associations for Non-Hodgkin Lymphoma with Varying Methods of Assigning Cumulative Benzene Exposure in the Shanghai Women’s Health Study (Friesen).”
Scientists can assess benzene exposure by using job exposure matrices (JEMs). A job exposure matrix assesses health hazard exposures in occupational health settings. Scientists build JEMs by determining generic population level job exposure estimates based on expert judgement. The experts’ estimates are anchored in actual exposure assessments correlated from various industrial chemical exposures.
Friesen states the researchers wanted greater insight into their previous findings and thus further examined the association between occupational benzene exposure and NHL diagnoses. They categorized exposures not simply to ever/never exposure determinations, but more extensively by length and intensity of benzene exposure using the JEMs model.
“All these metrics resulted in statistically significant exposure-response associations for NHL,” Friesen notes. “The robust associations observed here with varying benzene assessment methods provide support for a benzene-NHL association.”
The researchers found a mean NHL diagnosis age of 65, with 38 years as the average duration between the first year of benzene exposure and NHL diagnosis.
“Statistically significant exposure-response trends with NHL risk were observed for all categorical and continuous metrics based on the primary exposure definition,” Friesen said. Exposure-response relationships were still evident when using exposure definitions other than the primary definition, though none were statistically significant.
“This suggests that either the power to detect a difference was too limited compared to the primary definition or, more likely, that the JEM assignments of probability may have been incorrect for some occupations or industries. The latter is supported by the finding that the participants meeting the primary but not strict definition had a statistically significantly elevated NHL risk.”
Industries meeting the primary exposure definition include rubber products manufacturing, organic chemicals, motor vehicles, measuring tools and instruments, leather goods manufacturing, forge and foundry blank fabrication, furniture manufacturing, shoe manufacturing, crude oil processing, petroleum and natural gas extraction, and artificial crude oil production.
Specific occupations meeting the primary exposure definition include electric and electronic equipment assembly and installation, lab technicians and analysts, paints, makers of clocks, watches and precision instruments, printing workers, shoemakers and hat-makers, machine installers, engravers of artistic works, tire production and vulcanization workers, and oil refinery workers.
Benzene is an aromatic hydrocarbon compound used in the manufacture of plastics, resins and dyes and many other products. Numerous scientific studies detail benzene’s various adverse health effects, including causing acute myeloid leukemia, myelodysplastic syndrome, and non-Hodgkin’s lymphoma. According to the 14th Report of Carcinogens published by the U.S. Department of Health and Human Services’ National Toxicology Program, benzene is “known to be a human carcinogen based on sufficient evidence of carcinogenicity from studies in humans.”
Non-occupational exposure to benzene in the United States can come from cigarette smoke. Investigators have found benzene at levels attributed to increased health risks at gasoline filling stations and other areas of heavy motor vehicle traffic. The National Occupational Health Survey conducted from 1972 to 1974 estimated 147,600 U.S. workers were potentially exposed to benzene. The National Occupational Exposure Survey conducted from 1981 to 1993 estimated 272,000 U.S. workers, including 143,000 women, were potentially exposed to benzene at work. Occupational benzene exposure continues to occur in many jobs today.
If you believe your recent non-Hodgkin’s lymphoma diagnosis might be related to benzene exposure, please contact the trial attorneys of Allen Stewart, P.C. The firm has decades of combined experience in helping those who have developed cancer due to toxic exposure.