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Development of historical exposure estimates for an epidemiologic study of beryllium sensitization and chronic beryllium disease at a beryllium production facility.
Virji-MA; Schuler-CR; Stanton-MI; Day-GA; Stefaniak-AB; Kent-MS; Kreiss-K
Epidemiology 2008 Nov; 19(6)(S):S105
Background: a number of epidemiologic studies have reported elevated prevalence of beryllium sensitization and chronic beryllium disease among employees in specific work processes. However, exposure-response relationships have been inconsistent, perhaps due to exposure misclassification from a lack of accurate, precise and/or biologically relevant estimates of historical exposures. In 1999, an epidemiologic study surveyed 264 workers hired after 1/1/1994 at a beryllium production facility. Methods: personal (full-shift) beryllium exposure data from a 1999 exposure survey (n = 3,906) were used to obtain mean baseline exposure estimates (BEE) for 272 jobs in a job-exposure matrix (JEM). We used historical general-area air samples (n = 77,183) collected between 1994 and 1999 to estimate the fractional annual change in exposure for 29 different work-process areas. The data were modeled using tobit regression to account for the left censoring of the air samples (17%-98% <detection limit). Historical job-level exposure estimates were calculated by applying the fractional annual change to the BEEs of jobs in the respective work-process areas. Workers were assigned exposure estimates based on their reported work for a given year and the locations of their jobs. Results: the mean beryllium time weighted average BEEs for all jobs ranged from 0.01 µg/m3 for Administration to 28.01 µg/m3 for Atomizer Operator. Changes in exposure over time between 1999 and 1994 were observed in many of the work-process areas; some of these changes were non-linear and differed among work-areas. The overall median cumulative and average beryllium exposures were 1.49 µg/m3-years and 0.62 µg/m3 respectively for participants over their work histories. The historical exposure estimates will be validated using limited personal exposure data collected between 1994 and 1998. Conclusions: using our JEM, exposure-response analyses can be explored over a range of exposure metrics, including summary measures such as cumulative, annual, or peak exposures, with the ultimate objective of elucidating an exposure-response relationship.
Work-environment; Exposure-assessment; Exposure-methods; Occupational-exposure; Epidemiology; Biohazards; Biological-effects; Biological-factors; Biological-monitoring; Biological-systems; Chemical-hypersensitivity; Exposure-assessment; Exposure-levels; Exposure-methods; Statistical-analysis; Workplace-studies; Work-environment; Work-areas; Chemical-hypersensitivity
Issue of Publication
Epidemiology; ISEE 20th Annual Conference, Pasadena, California, October 12-16, 2008