Cohort study among workers exposed to benzene in China: II. Exposure assessment

Abstract

This report describes a retrospective exposure assessment method used in a follow-up mortality study of workers exposed to benzene. The approach quantified historical exposure to benzene in a multi-industry, multicenter cohort, involving 672 factories in 12 cities in China. Historical exposure data were collected to obtain exposure information related to 1,427 work units (departments) and 3,179 unique job titles from benzene-producing or -using factories in which written records and other data sources were evaluated. The basic unit for exposure assessment was a factory/work unit/job title combination which was considered separately during each of seven calendar-year time periods between 1949 and 1987 for a total of 18,435 exposure assignments. Historical information collected to estimate exposure included benzene monitoring data; lists of raw materials and factory products, and the percentage of benzene in each; the total amount and dates of use of benzene or benzene-containing materials; use of engineering controls and personal protective equipment; and other available exposure information. Overall, 38% (ranging from 3% for the earliest periods to 67% for the last period) of the estimates were based primarily on benzene monitoring data. In the absence of job-specific benzene monitoring data for a given calendar period, measurement results or exposure estimates for similar jobs and/or other calendar periods were used in conjunction with other exposure information to derive estimates. Estimated exposure levels are presented by industries and occupations. The highest average exposures during 1949-1987 were observed for the rubber and plastic industry (30.7 ppm), and for rubber glue applicators (52.6 ppm).

An epidemiologic study of early biologic effects of benzene in Chinese workers.

“…Exposure was estimated using a modification of the method used for the cohort study (7). This estimate incorporated work histories obtained by interview Subjects provided a baseline urine sample and then received 250 mg chlorzoxazone to evaluate CYP2E1 function (8,9) (results to be reported elsewhere).…”

Incidence and risk factors of aplastic anemia in Latin American countries: the LATIN case-control study

“…Due to its health risks, the use of benzene has now been restricted, and it has been replaced by other solvents containing little or no benzene. 24 The hematotoxic properties of benzene have been known for more than a century, [25][26][27][28][29] and this chemical has been the most convincingly associated with the development of AA. 4,30,31 A high number of individuals who have been exposed to benzene over periods of months or years have developed aplasia, with bone marrow cells becoming replaced with fat.…”

Agreement of job‐exposure matrix (JEM) assessed exposure and self‐reported exposure among adult leukemia patients and controls in Shanghai

“…Because Chinese workers hold fewer jobs and generally have fewer types of exposures in industrial jobs than Agreement of JEM Self-Reported Exposure in Shanghaiworkers in western industrialized countries, the potential for confounding by other hazardous substances is reduced [Dosemeci et al, 1994]. The high participation rate among eligible cases (91.4%) represented a successful field effort.…”

“…Several advantages have been noted in carrying out occupational epidemiologic investigations in the People's Republic of China in general to include large numbers of study subjects, fewer jobs held per subject, fewer exposures per subject, easier access to factory records, and administrative systems for tracing and follow-up [Dosemeci et al, 1994]. Because Chinese workers hold fewer jobs and generally have fewer types of exposures in industrial jobs than Agreement of JEM Self-Reported Exposure in Shanghaiworkers in western industrialized countries, the potential for confounding by other hazardous substances is reduced [Dosemeci et al, 1994].…”