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Exposure-response assessment of cancer mortality in styrene-exposed boatbuilders
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10 2020
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Source: Occup Environ Med. 77(10):706-712
Details:
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Alternative Title:Occup Environ Med
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Description:Objectives
To improve exposure estimates and reexamine exposure-response relationships between cumulative styrene exposure and cancer mortality in a previously studied cohort of U.S. boatbuilders exposed between 1959 and 1978 and followed through 2016.
Methods
Cumulative styrene exposure was estimated from work assignments and air-sampling data. Exposure-response relationships between styrene and select cancers were examined in Cox proportional hazards models matched on attained age, sex, race, birth cohort, and employment duration. Models adjusted for socioeconomic status (SES). Exposures were lagged 10-years or by a period maximizing the likelihood. Hazard ratios (HRs) included 95% profile-likelihood confidence intervals (CIs). Actuarial methods were used to estimate the styrene exposure corresponding to 10−4 extra lifetime risk.
Results
The cohort (n = 5,163) contributed 201,951 person-years. Exposures were right-skewed, with mean and median of 31 and 5.7 ppm-years, respectively. Positive, monotonic exposure-response associations were evident for leukemia (HR at 50 ppm-years styrene = 1.46; 95% CI: 1.04 to 1.97) and bladder cancer (HR at 50 ppm-years styrene = 1.64; 95% CI: 1.14 to 2.33). There was no evidence of confounding by SES. A working lifetime exposure to 0.05 ppm styrene corresponded to one extra leukemia death per 10,000 workers.
Conclusions
The study contributes evidence of exposure-response associations between cumulative styrene exposure and cancer. Simple risk projections at current exposure levels indicate a need for formal risk assessment. Future recommendations on worker protection would benefit from additional research clarifying cancer risks from styrene exposure.
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Pubmed ID:32471836
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Pubmed Central ID:PMC7494518
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