EXPOSURE TO STYRENE AND CHRONIC HEALTH-EFFECTS - MORTALITY AND INCIDENCE OF SOLID CANCERS IN THE DANISH REINFORCED-PLASTICS INDUSTRY

Objectives-To study the occurrence of non-malignant diseases and solid cancers in workers exposed to styrene in the Danish reinforced plasti cs industry. Methods-All 36 610 workers of 386 reinforced plastics com panies and 14 293 workers not exposed to styrene from similar industri es were followed up from 1970 to 1990. This industry is characterised by simple exposure conditions, exposure to high concentrations of styr ene, and a high proportion of small companies, and the exposure assess ment was based on experts' classification on a company level. The mort ality from nonmalignant causes and the incidence of solid cancers were compared with the national rates. Poisson models were used for intern al comparisons. Results-A total of 3031 deaths and 1134 newly diagnose d cases of solid cancer were reported in the workers in the reinforced plastics industry. In companies where 50% or more of the workers prod uced reinforced plastics an increased mortality rate ratio (MRR) for d egenerative disorders of the nervous system (multiple sclerosis, parki nsonism, and motor neurone disease; MRR 1.8, 16 cases, 95% confidence interval (95% CI) 0.9-3.8) and an increased incidence rate ratio (IRR) for pancreatic cancer (IRR 2.2, 17 cases, 95% CI 1.1-4.5) was found. For both disease categories increased occurrence was also found among long term workers, workers of the 1960s (the period with the highest e xposure to styrene), and workers with a latent period of more than 10 years after the start of employment. No other non-malignant diseases o r solid cancers showed these patterns. Conclusion-The findings have to be interpreted with caution, due to the company based exposure assess ment, but the possible association between exposures in the reinforced plastics industry, mainly styrene, and degenerative disorders of the nervous system and pancreatic cancer. deserves attention.