Occupational exposure to eight organic dusts and respiratory cancer among Finns

Abstract

Background: There is inconclusive evidence concerning cancer risks of organic dusts. Aim: The carcinogenic exposures are mainly inhalatory and the authors therefore studied associations between occupational exposure to eight different organic dusts and respiratory cancers in Finland. Methods: The authors followed up a cohort of all economically active Finns born between 1906 and 1945 for 30 million person-years during 1971-95. Incident cases of nasal, laryngeal, and lung cancer and mesotheliomas were identified through a record linkage with the Finnish Cancer Registry. Occupations from the population census in 1970 were converted to exposures to eight organic dusts with a jobexposure matrix (FINJEM). Cumulative exposure (CE) was calculated as a product of prevalence, level, and estimated duration of exposure. Standardised incidence ratios (SIR) and 95% confidence intervals (CI) adjusted for age, period, and social class were calculated for each organic dust using the economically active population as the reference. Results: A total of 20 426 incident cases of respiratory cancer were observed. Slightly increased risk was observed among men exposed to wood dust for nasal cancer (SIR 1.42, 95% CI 0.79 to 2.44). For laryngeal cancer, men exposed to plant dust (mainly grain millers) had a raised SIR in the high exposure class (SIR 3.55, 95% CI 1.30 to 7.72). Men exposed to wood dust had a raised SIR for lung cancer, but only in the low exposure class (SIR 1.11, 95% CI 1.04 to 1.18). Women exposed to wood dust showed an increased SIR for mesotheliomas in the low exposure class (SIR 4.57, 95% CI 1.25 to 11.7) and some excess in the medium exposure category. Conclusions: Exposure to organic dusts is unlikely to be a major risk factor of respiratory cancer. Even exposure to wood dust which is a major exposure in Finland seems to have minor effect for nasal cancer. The authors found suggestive evidence that exposure to grain dust may increase the risk of laryngeal cancer, and some support to the hypothesis that exposure to textile dust, and to plant and animal dust (agricultural dusts) may decrease the risk of lung cancer.

Occupational wood dust exposure and the risk of laryngeal cancer: A population based case‐control study in Germany

“…Since IARC reviewed wood dust as carcinogenic to humans [IARC, 1995] the results for wood dust and its association with other upper aero digestive tract and respiratory cancers is still inconsistent [Laakkonen et al, 2006;Jayaprakash et al, 2008]. In our study we confirm the most recent findings for laryngeal cancer and wood dust of Jayaprakash et al who concluded recently, that wood dust exposure is a potential risk factor especially for cancers of nasal cavity, nasopharynx, larynx and lung.…”

“…It is hypothesized that hard wood dust is associated with a larger hazard then softwood because more cell shattering occurring with hardwoods results in smaller dust particles [IARC, 1995;Ward et al, 1997]. While it is well accepted that exposure to hardwood dust increases the risk of nasal cancer, it is not clear to what extend hardwood dust is also associated with adjacent upper respiratory sites [Blot et al, 1997;Laakkonen et al, 2006]. Vaughan and Davis [1991] did not find an association between hardwood dust exposure and laryngeal cancer [Vaughan and Davis, 1991].…”

Cancer incidence among workers exposed to softwood dust in Lithuania: Table 1

“…No increased risk of upper respiratory and lung cancer was found among Finnish woodworkers exposed to wood dust, mainly from pine, spruce and birch, at a level of about 1 mg/m 3 13. Another Finish study identified an elevated risk of nasal and lung cancer 5. A case–control study performed in Washington State found exposure to softwood dust did not increase the risk of lung cancer 14…”

Wood dust exposure and risk of lung cancer

“…In a cohort study of furniture workers in Estonia, there was no evidence of increased incidence of lung cancer compared to the general population,18 and an increased risk was not observed when evaluating ‘moderate’ or ‘high’ exposure jobs or when considering various durations of employment. A recent occupational cohort study used a job–exposure matrix to evaluate cumulative exposure to a variety of organic dusts and also found no evidence of increased lung cancer risk with increasing exposure to wood dust 20. While the study used quantitative exposure data, exposure levels were assigned based on job titles rather than subject-specific occupational histories.…”