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A retrospective cohort mortality study and an industrial hygiene assessment were undertaken in two styrene-butadiene rubber producing facilities in eastern Texas. Occupational history records were available from 1943 at plant A and from 1950 at plant B to the study cut-off date of 31 March 1976. With a two-sided test statistic, no statistically significant excesses in total or cause-specific mortality were observed for the overall worker population of either plant. However, the plant A study group demonstrated a nonsignificant statistical excess [standardized mortality ratio (SMR) of 203] for the cause-specific category of leukemia and aleukemia. Additional analyses were performed on a subgroup consisting of all white males with at least six months of employment at plant A between the beginning of 1943 and the end of 1945, a time which coincided with process and operational changes. An SMR of 278, also not statistically significant, was demonstrated for the leukemia and aleukemia cause-specific category. Due to the relative modest study population sizes, the power of this study to detect statistically significant excesses in leukemias or other malignancies of the hematopoietic and lymphatic tissues is not very large unless one is interested in substantial excesses, such as those that would correspond to a fourfold increase in risk.

The United States National Institute for Occupational Safety and Health (NIOSH) began an epidemiologic study of workers employed in the styrene-butadiene rubber (SBR) industry during 1976. This study was prompted by reports of relatively high numbers of leukemia deaths occurring within SBR production work populations. Simultaneous with the initiation of this investigation, the University of North Carolina released a report associating an excess risk of death due to hematopoietic and lymphatic malignancies among workers producing several synthetic rubbers, including SBR. This report presents NIOSH's preliminary mortality observations and a discussion of progress made on the analyses of contaminants found in two SBR production facilities. Currently, NIOSH is determining the feasibility of doing an epidemiologic study in the reinforced plastics industry. Interest in this study developed as part of an effort to determine health hazards associated with occupational exposure to styrene. Most of the technology for the reinforced plastics industry developed in the 1950s, and therefore this process represents a relatively new industry. This report also includes information on environmental conditions observed in the reinforced plastics industry and enumerates some of the complicating characteristics of this industry which increase the complexity of this study.