Sinonasal adenocarcinoma following styrene exposure in the reinforced plastics industry.

BACKGROUND: Sinonasal adenocarcinoma is a rare disease expected to have rare causes and potential for strong risk factors as reflected by the strong association with occupational wood dust exposure. High level styrene exposure is a rare and suspected carcinogen, and this study examines the exposure-response relation between occupational styrene exposure, sinonasal adenocarcinoma and other subtypes. METHODS: We followed 73 092 styrene-exposed workers from 1968 to 2011 and identified sinonasal cancers in the Danish Cancer Registry. We modelled cumulative styrene exposure and estimated incidence rates and age, sex and wood-industry adjusted ORs. RESULTS: During 1 585 772 person-years, we observed nine cases of adenocarcinoma, corresponding to a fivefold non-significantly increased OR for estimates of high versus low cumulative styrene exposure (OR 5.11, 95% CI 0.58 to 45.12). The increased risk was confined to exposure received during the recent 15 years. The other histological subtypes showed no increased risk. CONCLUSION: This study suggests increased risk of sinonasal adenocarcinoma following styrene exposure. The observations are, however, few, confounding from wood dust exposure cannot be ruled out, and additional studies are needed before firm conclusions can be drawn.

Styrene Exposure and Risk of Lymphohematopoietic Malignancies in 73,036 Reinforced Plastics Workers.

BACKGROUND: Styrene is an important industrial chemical that the general population is exposed to at low levels. Previous research has suggested increased occurrence of leukemia and lymphoma among reinforced plastics workers exposed at high levels of styrene. METHODS: We followed 73,036 workers of 456 small- and medium-sized Danish reinforced plastics companies from 1968 to 2011 and investigated the exposure-response relation between cumulative styrene exposure and incidence of lymphohematopoietic malignancies. We modeled styrene exposure from employment history, survey data, and historical styrene exposure measurements. We retrieved information on lymphohematopoietic malignancies from national cancer and patient registers. RESULTS: We identified 665 cases overall of 21 different lymphohematopoietic malignancies or combinations thereof, each with at least 20 cases, during 1,581,976 person-years of follow-up. Initial analyses suggested higher age, sex, and calendar year-adjusted incidence rate ratios (RRs) for acute myeloid leukemia, Hodgkin lymphoma, and T-cell lymphoma with higher estimates of cumulative styrene exposure. Accounting for time since exposure showed a trend by cumulative styrene exposure (P = 0.01) and a doubled risk (RR = 2.4; 95% CI, 1.2, 4.6) of acute myeloid leukemia following estimated high compared with estimated low cumulative exposure during the prior 15-29 years. We observed no increased risk following exposure during more recent years and less consistent risk patterns for Hodgkin lymphoma and T-cell lymphoma. CONCLUSIONS: This study, to our knowledge the largest epidemiologic study to date of occupational styrene exposure, suggests increased risk of acute myeloid leukemia following high styrene exposure with a latency period of about 15 years.

Cancer Incidence in Workers Exposed to Styrene in the Danish-reinforced Plastics Industry, 1968-2012.

BACKGROUND: Occupational exposure to styrene is widespread and has been suggested to be carcinogenic. The aim of this study was to investigate whether occupational exposure to styrene increases the risk of cancer, in particular lymphohematopoietic cancers. METHODS: We established a study population of 72,292 workers employed in 443 small and medium-sized companies producing reinforced plastics 1964-2007 by utilizing several national registries, expert assessment, and worker survey data. We identified incident cancer cases from 1968 to 2012 in the national Danish cancer registry and computed standardized incidence rate ratios (SIRs) with 95% confidence intervals (95% CI) based on national rates. RESULTS: Increasing SIRs of Hodgkin lymphoma, myeloid leukemia, and cancer of nasal cavities and sinuses were inconsistently associated with increasing duration of employment, early year of first employment, or styrene exposure probability. No such trends were observed for cancer of the esophagus, pancreas, lung, kidney, or urinary bladder, which have previously been associated with styrene exposure. Lung cancer showed an overall increased risk that decreased by duration of employment. CONCLUSION: Occupational styrene exposure may be associated with Hodgkin lymphoma, myeloid leukemia, and cancer of nasal cavities and sinuses. Further studies are needed to evaluate if the observed associations are likely to be causal.