An Evaluation of Modeled Benzene Exposure and Dose Estimates Published in the Chinese–National Cancer Institute Collaborative Epidemiology Studies

Benzene and lymphohematopoietic malignancies in humans†

“…When concluding that a threshold benzene concentration exceeding 50±75 ppm is necessary to induce mild to modest declines in total white blood cell counts, Budinsky et al [1999] misinterpret earlier reports [Kippen et al, 1989;Cody et al, 1993] and fail to consider more recent evidence Ward et al, 1996]. As with benzene-associated risk for leukemia, there is no clear evidence of a threshold below which benzene does not cause hematotoxicity in humans Ward et al, 1996].…”

“…The NCI±CAPM study extends epidemiologic data to exposure levels not adequately investigated in the past. In the commentaries of Budinsky et al [1999] and Wong [1999] several issues were raised about methods used in the NCI±CAPM study.…”

“…1, Panel A). Wong [1995] and Budinsky et al [1999] suggest that the absence of demonstrated risk at lower levels of exposure is evidence for an exposure threshold below which benzene exposure is safe. In fact, the data from the Plio®lm cohort are essentially uninformative at doses below 200 ppm-years.…”

“…It was argued that the exposure assessment procedure used in the NCI±CAPM study misclassi®ed large numbers of highly exposed workers as having low levels of exposure and, speci®cally, that the exposure assessment approach did not adequately consider workers with high-dose exposures [Budinsky et al, 1999;Wong, 1999].…”

“…Since 1987, the U.S. National Cancer Institute (NCI) has collaborated with the Chinese Academy of Preventive Medicine in a large-scale epidemiologic study of cancer risk among workers exposed to benzene in China (NCI-CAPM Study). Recent commentaries [Wong, 1998[Wong, , 1999Budinsky et al, 1999] have raised questions about several aspects of the National Cancer Institute/Chinese Academy of Preventive Medicine (NCI/CAPM) cohort study, including methodologic aspects of exposure assessment, the wide range of hematopoietic disorders reported to be associated with benzene exposure, and the appropriate interpretation of the data in the light of the entirety of the scienti®c literature on health effects of benzene exposure. We review the evidence implicating benzene in the etiology of an array of hematopoietic disorders, clarify methodologic aspects of the approach used in the NCI/CAPM study, and examine the NCI/CAPM study in the context of the broader literature on health effects associated with occupational benzene exposure.…”