Effects of benzene exposure on white blood cell and hemoglobin levels among workers from Shanghai Huaxiang Rubber Factory [electronic resource]

9781109520835

2009

1 online resource (105 p.)

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Benzene has been characterized as a human carcinogen for long time. One of the effects of benzene is its hematotoxicity, which causes pancytopenia (reduction of red and white blood cells as well as platelet). Despite hundreds of epidemiological and laboratory researches on the health effects of the molecule, most of the studies are cross-sectional, which are weak in capturing the change of blood data over the course of benzene exposure. Moreover, the dose-response relationship of benzene and hematological effects in low level exposure remains controversial. To further investigate the effect of benzene, a cohort of workers in Shanghai Huaxiang Rubber Factory in China was followed from late 1960's to 2007. Longitudinal data on benzene exposure levels and blood cell counts were collected and analyzed by fitting a linear mixed model, so that transient hematological effects were captured and the time trend of the effects was estimated. The study involved 205 workers and more than 2000 observations, corresponding to a wide range of benzene exposure levels of 0∼525 mg/m3 time weighted average (TWA) concentration. The analysis suggests that higher levels of benzene exposure correlate with reduced white blood cell levels for the blood data collected by automated machine counting. Elevated cumulative benzene exposure negatively associated with WBC levels among male workers. Nevertheless, the average blood counts for the exposed workers were still within the normal range. In general, the average WBC level displayed a rising trend. On the other hand, the impact of benzene exposure on hemoglobin levels was not conclusive. This is the first time application of mixed model in the analysis of benzene hematological effects among similar benzene studies, which are mostly cross-sectional and did not take into account of the time variable.

Books / Online / Dissertations & Theses

English

July 12, 2011

Thesis (M.P.H.)--Yale University, 2009.

Yale University. School of Public Health.