Harvard Studying Asphalt - Work Risks

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Summary Statement

A short description of a study being conducted to assess the risks of working with asphalt
May 1998

Researchers at the Harvard University School of Public Health are studying evidence of asphalt exposures in construction workers and ways to control such exposures. The goal of the 4-year, $1.3 million study is to reduce cancer risks.

Scientific studies say asphalt workers have a high risk of some cancers, such as lung cancer. And some hydrocarbons in asphalt cause cancers in animals. But no study has tied asphalt exposures to worker cancers.

Asphalt is made from petroleum and contains polycyclic aromatic hydrocarbons (PAHs). The study will look for "biomarkers" for PAHs in workers' blood and urine. A biomarker for a chemical shows that it's in the body and, so, the person may be at increased risk of disease. Biomarkers have not been measured systematically in asphalt workers; past studies focused on what was in the air.

Pam Susi, of CPWR – Center for Construction Research and Training (CPWR) is a technical adviser to the Harvard team, Robert Herrick and David Christiani. At CPWR, Susi works on ways to measure worker exposures to toxic substances.

The researchers are taking measurements in the field, said Herrick, the lead investigator. About 50 roofers and 50 pavers in New England will participate. Each worker will have a blood test 4 times in the second year, 1999. The tests will look for differences in biomarkers between the summer and the winter, when almost no asphalt work is done. At the end of each workday in 1999, each worker will fill out a short questionnaire about the work and work conditions Ñ such as the number of hours spent on tasks and whether the worker used personal protective equipment. The questions will look for factors that affect PAH exposure and dose. The researchers plan to produce an exposure-dose history for each worker.

The study, funded by the National Cancer Institute, will consider potential non-work-related sources of PAHs, such as cigarette smoking and food.

In the study's last year, respirators, gloves, and other measures will be used to see if biomarkers - - asphalt exposures - can be reduced.

The study should help future studies of disease patterns among pavers, roofers, and other occupations. The National Institute for Occupational Safety and Health in 1995 estimated more than 470,000 workers are exposed to asphalt, with 221,000 of them in construction. Asphalt is in paving, roofing, flooring, waterproofing, and corrosion protection.