Occupational Noise Exposure and Vestibular Schwannoma: A Case-Control Study in Sweden

It has been suggested that the association between self-reported occupational noise exposure and vestibular schwannoma (VS), found in several studies, represents recall bias. Therefore, we aimed to study the relationship in a large case-control study using occupational noise measurements. We performed a case-control study using data from Sweden for 1,913 VS cases diagnosed in 1961-2009 and 9,566 age- and sex-matched population controls. We defined occupational history by linkage to national censuses from 1960, 1970, 1980, and 1990. We estimated occupational noise exposure for each case and control using a job-exposure matrix. There was no association between occupational noise exposure and VS. Among subjects assessed as ever exposed to occupational noise levels of ≥85 dB (214 cases and 1,142 controls), the odds ratio for VS per 5 years of exposure was 1.02 (95% confidence interval: 0.90, 1.17). Workers with noise levels of ≥85 dB for at least 15 years (5-year latency period), showed no increased risk of VS (odds ratio = 0.98, 95% confidence interval: 0.73, 1.31) compared with those who had never been exposed to noise levels of 75 dB or higher. In summary, our large study does not support an association between occupational noise exposure and VS.

Occupational exposures and male breast cancer: A nested case-control study in the Nordic countries

BACKGROUND

Male breast cancer (MBC) is a rare and understudied disease. There is limited evidence on association between environmental and occupational agents and MBC. Some similarities in risk factors may be shared with female breast cancer. We evaluated solvents, metals, exhaust gases and other agents in relation to MBC within the large Nordic Occupational Cancer Study (NOCCA).

METHODS

The study included 1469 MBC cases and 7345 controls from Finland, Iceland and Sweden, matched for the date of birth, sex and country. Cases were identified through national cancer registries. Data on occupation and other demographic indicators were collected from census records and population registries. Overall, 24 occupational exposures were assessed. Exposure estimates were assigned by linking job titles to job-exposure matrices (NOCCA-JEM). Odds ratios (OR) and 95% confidence intervals (95% CI) were estimated by using conditional logistic regression models.

RESULTS

Significantly decreased overall OR was observed for physical workload (OR = 0.78, 95% CI 0.67-0.91). Protective effect of physical workload was stronger by increasing exposure level with significant dose-response relationship (p-trend<0.01). Non-significantly increased ORs were observed for trichloroethylene, iron, lead, chromium, welding fumes and wood dust, and decreased ORs for asbestos, silica dust and perchloroethylene. However, these results were not consistent across all analyses.

CONCLUSIONS

The current study showed 20-25% protective effect for physical workload at work, while no strong evidence for other agents was observed.

Time trends and occupational variation in the incidence of testicular cancer in the Nordic countries

OBJECTIVE

To describe the trends and occupational variation in the incidence of testicular cancer in the Nordic countries utilising national cancer registries, NORDCAN (NORDCAN project/database presents the incidence, mortality, prevalence and survival from >50 cancers in the Nordic countries) and NOCCA (Nordic Occupational Cancer) databases.

PATIENTS AND METHODS

We obtained the incidence data of testicular cancer for 5-year periods from 1960-1964 to 2000-2014 and for 5-year age-groups from the NORDCAN database. Morphological data on incident cases of seminoma and non-seminoma were obtained from national cancer registries. Age-standardised incidence rates (ASR) were calculated per 100 000 person-years (World Standard). Regression analysis was used to evaluate the annual change in the incidence of testicular cancer in each of the Nordic countries. The risk of testicular cancer in different professions was described based on NOCCA information and expressed as standardised incidence ratios (SIRs).

RESULTS

During 2010-2014 the ASR for testicular cancer varied from 11.3 in Norway to 5.8 in Finland. Until 1998, the incidence was highest in Denmark. There has not been an increase in Denmark and Iceland since the 1990s, whilst the incidence is still strongly increasing in Norway, Sweden, and Finland. There were no remarkable changes in the ratio of seminoma and non-seminoma incidences during the past 50 years. There was no increase in the incidences in children and those of pension age. The highest significant excess risks of testicular seminoma were found in physicians (SIR 1.48, 95% confidence interval [CI] 1.07-1.99), artistic workers (SIR 1.47, 95% CI 1.06-1.99) and religious workers etc. (SIR 1.33, 95% CI 1.14-1.56). The lowest SIRs of testicular seminoma were seen amongst cooks and stewards (SIR 0.56, 95% CI 0.29-0.98), and forestry workers (SIR 0.64, 95% CI 0.47-0.86). The occupational category of administrators was the only one with a significantly elevated SIR for testicular non-seminoma (SIR 1.21, 95% CI 1.04-1.42). The only SIRs significantly <1.0 were seen amongst engine operators (SIR 0.60, 95% CI 0.41-0.84) and public safety workers (SIR 0.67, 95% CI 0.43-0.99).

CONCLUSIONS

There have always been differences in the incidence of testicular cancer between the Nordic countries. There is also some divergence in the incidences in different age groups and in the trends of the incidence. The effect of occupation-related factors on incidence of testicular cancer is only moderate. Our study describes the differences, but provides no explanation for this variation.