| This investigation evaluated the relation between 1,3-butadiene, styrene, and dimethyldithiocarbamate (DMDTC) and mortality from lymphohematopoietic cancer during the time period 1944 through 1998 among 17,924 men employed in the synthetic rubber industry. Cumulative exposure to 1,3-butadiene was associated positively with all leukemia, with chronic myelogenous leukemia, and to a lesser extent with chronic lymphocytic leukemia. Results of uncertainty analyses supported the presence of a positive relation between butadiene and leukemia. Styrene and DMDTC also were associated positively with leukemia. Exposures to these agents were correlated with butadiene, and data on the independent effect of each of the three chemicals on leukemia were limited. After controlling for the effect of butadiene, there was no consistent exposure-response relation between either styrene or DMDTC and all leukemia, chronic myelogenous leukemia, or chronic lymphocytic leukemia, although a positive association between any exposure to DMDTC and leukemia persisted. The data from this study indicate that employment in the synthetic rubber industry is related causally to leukemia. Uncertainty remains about the specific agent(s) responsible for the association. The carcinogenic mechanisms through which butadiene, styrene, or DMDTC could cause leukemia in humans have not been established, and external epidemiologic support for a leukemogenic role is limited for these agents. Styrene and DMDTC were associated positively with non-Hodgkin's lymphoma. There is little external support for this association. The study did not find any clear relation between exposure to butadiene, styrene, or DMDTC and multiple myeloma. |
