Biomarkers

O17.1 THE DOSE-RESPONSE RELATION BETWEEN BENZENE AND PERIPHERAL BLOOD CELL COUNTS

R. Vermeulen¹, Q. Lan¹, xLLan², G. L. Li³, M. Shen¹, S. M. Rappaport⁴, S. Kim⁴, S. Waidyanatha⁴, LinYu-Sheng⁴, R. B. Hayes¹, M. Linet¹, W. Guo², S. Yin³, N. Rothman¹, M. T. Smith².¹National Cancer Institute, MD, Bethesda, USA; ²University of California, Berkeley, CA, USA; ³Chinese Center for Disease Control and Prevention, Beijing, China; ⁴University of North Carolina, Chapel Hill, NC, USA

Introduction: Benzene is known to have toxic effects on the blood and bone marrow, but its impact at levels below the US occupational standard of 1 ppm remains uncertain. Furthermore, it has been hypothesised based on metabolic observations that benzene may have non-linear health effects.

Methods: We carried out a molecular epidemiology study of 250 exposed subjects and 140 unexposed subjects to evaluate haematologic, cytogenetic, and molecular endpoints in workers exposed to benzene, with a particular focus on exposures below 10 ppm. The study comprised a comprehensive exposure survey in which over a period of 16 months, 2783 personal air samples and 113 dermal measurements were collected complemented with urinary measurements of benzene and its metabolites and protein adducts of benzene oxide (BO) and 1,4-benzoquinone (1,4-BQ).

Results: The detailed exposure assessment enabled estimation of time specific individual exposure levels. In the last month before phlebotomy the median individual exposure of all 250 exposed workers was 1.2 ppm (10th–90th percentiles: 0.3–13.8 ppm) with 109 subjects exposed to less than 1 ppm. Exposure to other solvents except toluene was minimal and did not correlate with benzene exposure. We have previously reported that granulocyte, lymphocyte, B-cell, and platelet counts decreased with increasing benzene exposure and were significantly decreased …