Characterizing occupational radon exposure greater than 100 Bq/m3 in a highly exposed country.

Radon is an established lung carcinogen concentrating in indoor environments with importance for many workers worldwide. However, a systematic assessment of radon levels faced by all workers, not just those with direct uranium or radon exposure, has not previously been completed. The objective of this study was to estimate the prevalence of workers exposed to radon, and the level of exposure (> 100-200 Bq/m3, 200-400 Bq/m3, 400-800 Bq/m3, and > 800 Bq/m3) in a highly exposed country (Canada). Exposures among underground workers were assessed using the CAREX Canada approach. Radon concentrations in indoor workplaces, obtained from two Canadian surveys, were modelled using lognormal distributions. Distributions were then applied to the susceptible indoor worker population to yield the number of exposed workers, by occupation, industry, province, and sex. In total, an estimated 603,000 out of Canada's 18,268,120 workers are exposed to radon in Canada. An estimated52% of exposed workers are women, even though they comprise only 48% of the labour force. The majority (68%) are exposed at a level of > 100-200 Bq/m3. Workers are primarily exposed in educational services, professional, scientific and technical services, and health care and social assistance, but workers in mining, quarrying, and oil and gas extraction have the largest number of exposed workers at high levels (> 800 Bq/m3). Overall, a significant number of workers are exposed to radon, many of whom are not adequately protected by existing guidelines. Radon surveys across multiple industries and occupations are needed to better characterize occupational exposure. These results can be used to identify exposed workers, and to support lung cancer prevention programs within these groups.

Estimating the burden of lung cancer in Canada attributed to occupational radon exposure using a novel exposure assessment method.

OBJECTIVE: Exposure to radon causes lung cancer. The scope and impact of exposure among Canadian workers have not been assessed. Our study estimated occupational radon exposure in Canada and its associated lung cancer burden. METHODS: Exposed workers were identified among the working population during the risk exposure period (1961-2001) using data from the Canadian Census and Labour Force Survey. Exposure levels were assigned based on 12,865 workplace radon measurements for indoor workers and assumed to be 1800 mg/m3 for underground workers. Lung cancer risks were calculated using the Biological Effects of Ionizing Radiation (BEIR) VI exposure-age-concentration model. Population attributable fractions were calculated with Levin's equation and applied to 2011 Canadian lung cancer statistics. RESULTS: Approximately 15.5 million Canadian workers were exposed to radon during the risk exposure period. 79% of exposed workers were exposed to radon levels < 50 Bq/m3 and 4.8% were exposed to levels > 150 Bq/m3. We estimated that 0.8% of lung cancers in Canada were attributable to occupational radon exposure, corresponding to approximately 188 incident lung cancers in 2011. CONCLUSIONS: The lung cancer burden associated with occupational radon exposure in Canada is small, with the greatest burden occurring among those exposed to low levels of radon.

Burden of non-melanoma skin cancer attributable to occupational sun exposure in Canada.

PURPOSE: Outdoor workers are exposed daily to solar ultraviolet radiation, an important contributor in the development of non-melanoma skin cancer. This study aimed to quantify the health burden of non-melanoma skin cancers among outdoor workers in Canada. METHODS: Solar ultraviolet radiation exposure and estimates of exposure levels were applied to employment information from Canada census data to determine the exposed population in the risk exposure period (1961-2001). Risk estimates were drawn from meta-analyses selected based on quality and relevance to the current study. Population-attributable fractions were calculated using Levin's equation and attributable cases were estimated based on incidence data reported by the Canadian Cancer Society. RESULTS: In 2011, 6.31% (4556 cases) of non-melanoma skin cancer cases were estimated to be attributable to occupational exposure to solar ultraviolet radiation. The majority of these cases occurred in men in the agriculture or construction industries. CONCLUSIONS: These estimates of the burden of non-melanoma skin cancer in Canada identify the need for further prevention efforts, particularly in agriculture and construction. Introducing workplace sun safety measures could be an important area for policy development.

[Mutagenic analysis on the polyhedrin gene (polh) of Bombyx mori nuclear polyhedrosis virus (BmNPV)].

In our early studies, the abnormal shape of the polyhedra of Bombyx mori nuclear polyhedrosis virus (BmNPV) induced by chemical mutagens of MMC. 9-AA and EMS occurred, and the genome of the mutated BmNPV obtained from the successive test had some change in the restriction endonuclease partners of EcoRI, BglII and BamHI. The present studies showed that the arrangement of the crystal lattice of the polyhedrin was disorderly, and the SDS-PAGE electropherogram of the polyhedrin depicted distinct change in comparison with control group. The results of sequencing analysis showed that many point mutations with characteristics of the base substitution had occurred at some sites of the BmNPV polh gene in three mutated groups, and these results funther revealed molecular mutagenesis of the mutagens effective to BmNPV. It was not confirmable that the point mutations of polh gene in the mutated BmNPV have relationship to abnormal shape of the polyhedra.