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What this paper adds Styrene, a widely used industrial chemical, is a neurotoxicant and classified by the International Agency for Research on Cancer (IARC) as a possible carcinogen (2B) and by the 12th Report on Carcinogens as reasonably anticipated to be a human carcinogen. IARC classifies styrene oxide, the main metabolite, as a probable carcinogen (2A).
This paper adds 13 years of follow-up of a cohort of boat builders and assesses the cancer and other chronic disease risks.
Styrene-exposed workers had excess mortality from lung cancer and chronic obstructive pulmonary disease (COPD). Workers with potential high-styrene exposure had a twofold increase in COPD mortality.
Introduction
Styrene is an organic solvent used to make synthetic rubber, plastics and resins. As of 2012, more than 5000 US manufacturing plants produced or fabricated styrene products and employed about 90 000 workers. 1 The current Occupational Safety and Health Administration (OSHA) permissible exposure limit is 100 ppm time-weighted average (TWA) over an 8 h workday. 2 The National Institute for Occupational Safety and Health (NIOSH) recommended exposure limit is 50 ppm. 3
The International Agency for Research on Cancer (IARC) classifies styrene in group 2B, possibly carcinogenic to humans, and the major human metabolite, styrene-7, 8-oxide, in group 2A, probably carcinogenic to humans. 4 5 Styrene and styrene oxide have been classified as reasonably anticipated to be human carcinogens by the Report on Carcinogens. 6
We updated a cohort mortality study of boat builders to further evaluate the carcinogenicity of styrene. Our previous analysis of all 5203 workers found excess oesophageal (standardised mortality ratio (SMR) 2.3, CI 1.2 to 4.0) and prostate (SMR=1.7, CI 1.1 to 2.5) cancer, and accidents (SMR=1.3, CI 1.0 to 1.5), and among workers highly exposed to styrene, urinary tract cancer (SMR=3.4, CI 1.3 to 7.5) and respiratory disease (SMR=2.5, CI 1.3 to 4.4). 7
Because of the possible association of styrene exposure with bronchiolitis obliterans and because bronchiolitis obliterans is considered difficult to diagnose and confused with other causes of airway obstruction, we decided to also investigate respiratory disease, specifically chronic obstructive pulmonary disease (COPD), in this cohort.
In previous analyses of this cohort both potential latency and statistical power to detect an increase in mortality from lymphatic and haematopoietic neoplasms, the a priori...