Risk of cancer in workers exposed to styrene at eight British companies making glass-reinforced plastics

Abstract

Objectives-To provide further information on the risks of lympho-haematopoietic (LH) and other cancers associated with styrene Methods-We extended follow-up to December 2012 for 7,970 workers at eight companies in England which used styrene in the manufacture of glass-reinforced plastics. Mortality was compared with that for England and Wales by the person-years method, and summarised by standardised mortality ratios (SMRs) with 95% confidence intervals (CIs). A supplementary nested case-control analysis compared styrene exposures, lagged by five years, in 122 incident or fatal cases of LH cancer and 1,138 matched controls.Results-A total of 3,121 cohort members had died (2,022 since the last follow-up). No elevation of mortality was observed for LH cancer, either in the full cohort (62 deaths, SMR 0.90, 95%CI 0.69-1.15), or in those with more than background exposure to styrene (38 deaths, SMR 0.82, 95%CI 0.58-1.14). Nor did the case-control analysis suggest any association with LH cancer. In comparison with background exposure, the odds ratio for non-Hodgkin lymphoma/chronic lymphocytic leukaemia in workers with high exposure (estimated eight-hour time-weighted average of 40-100 ppm) for ≥ I year was 0.54 (95%CI 0.23-1.27). Mortality from lung cancer was significantly elevated, and risk increased progressively across exposure categories, with an SMR of 1.44 (95%CI 1.10-1.86) in workers highly exposed for ≥1 year.Conclusions-We found no evidence that styrene causes LH cancer. An association with lung cancer is not consistently supported by other studies. It may have been confounded by smoking, but would be worth checking further.

Mortality among styrene-exposed workers in the reinforced plastic boatbuilding industry

“…The recently updated British styrene cohort also had an excess of lung cancer deaths, especially among workers with high-styrene exposure, and, like us, no leukaemia or lymphoma excess 27. However, a recent update of a large (N=15 826) US study of workers in the reinforced plastics industry originally studied by Wong and colleagues32 33 found an increase in lung cancer mortality, but with an inverse trend with exposure,26 and a previous update had found an increase in mortality from ‘other respiratory diseases’, but only in short-term (<1 year) or low-exposure workers 33.…”

“…Previous reviews and studies of lymphatic and haematopoietic neoplasm in styrene-exposed workers4 22 have varied widely, including a statistically significant deficit of cancer deaths,26 a lack of association with styrene,27 and a moderate association of increased lymphoma and leukaemia mortality with longer latency and higher average level of exposure 28. Incidence studies are preferred over mortality studies for cancers with relatively high survival rates, such as lymphohaematopoietic cancers 29 30.…”

Cancer mortality update with an exposure response analysis among styrene‐exposed workers in the reinforced plastics boatbuilding industry

“…Other studies of workers in RPC have shown mixed results with regard to styrene exposure and leukemia risk. Twoseparate, recent studies considering RPC workers in the United States and Britain did not find an association between styrene exposure and leukemia mortality in external comparisons nor in internal comparisons by styrene exposure. However, analysis of a cohort of Danish RPC workers did find higher standardized incidence ratio (SIR) values for myeloid leukemia with longer duration of employment and higher styrene exposure probability.…”

“…Among positive studies, modestly increasing exposure‐related lymphohematopoietic cancers (LHCs), including leukemias and non‐Hodgkin lymphoma (NHL), were reported most often . In addition, increased lung cancer risk has also been observed in many styrene‐exposed cohorts and has also been found in a laboratory study of mice exposed to styrene . Less frequent findings include elevated risk of cancers of the bladder, larynx, kidney, esophageal, and nasal cavities …”

Sinonasal cancer and exposure to styrene

“…Our cohort included 3488 laminators with exposures to styrene in the order of 40–100 parts per million (ppm), in many cases for a year or longer. We extended our follow-up of this cohort at the end of 2012 3. In response to the call from Nissen and colleagues1 for more studies, we have revisited our analysis of the most recent follow-up, examining mortality from 1946 to December 2012.…”