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Original research
Exposure–response assessment of cancer mortality in styrene-exposed boatbuilders

Abstract

Objectives To improve exposure estimates and reexamine exposure–response relationships between cumulative styrene exposure and cancer mortality in a previously studied cohort of US 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 maximising the likelihood. HRs included 95% profile-likelihood CIs. Actuarial methods were used to estimate the styrene exposure corresponding to 10-4 extra lifetime risk.

Results The cohort (n= 5163) 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 leukaemia (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 leukaemia 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.

  • cancer
  • epidemiology
  • risk assessment
  • retrospective exposure assessment
  • occupational health practice
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Footnotes

  • Contributors Data collection was accomplished by contributors to previous studies, including RDD and SJB. RDD and SJB participated in design, analysis and manuscript development. Both authors participated in the interpretation and presentation of results and have read and approved the final manuscript.

  • Funding This research was conducted as part of routine duties of NIOSH staff. No external funds were used.

  • Disclaimer The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Ethics approval This work was conducted at the National Institute for Occupational Safety and Health, which is part of the Centers for Disease Control and Prevention (CDC) under the US Department of Health and Human Services. The research was approved by the NIOSH Human Subjects Review Board.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement Data are available on reasonable request. Study data are maintained by the National Institute for Occupational Safety and Health (NIOSH) of the Centers for Disease Control and Prevention (CDC) according to the Privacy Act System Notice 09-20-0147. Some data are protected by an Assurance of Confidentiality authorised under Section 308(d) of the Public Health Service Act (42 U.S.C. 242m). Data may be accessible on reasonable requests meeting the provisions of these protections and CDC data sharing policies made to NIOSH, via the corresponding author.

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