Diesel Engine Exhaust Exposure in the Ontario Civil Infrastructure Construction Industry.

OBJECTIVES: Diesel engine exhaust (DEE) is a known lung carcinogen and a common occupational exposure in Canada. The use of diesel-powered equipment in the construction industry is particularly widespread, but little is known about DEE exposures in this work setting. The objective of this study was to determine exposure levels and identify and characterize key determinants of DEE exposure at construction sites in Ontario. METHODS: Elemental carbon (EC, a surrogate of DEE exposure) measurements were collected at seven civil infrastructure construction worksites and one trades training facility in Ontario using NIOSH method 5040. Full-shift personal air samples were collected using a constant-flow pump and SKC aluminium cyclone with quartz fibre filters in a 37-mm cassette. Exposures were compared with published health-based limits, including the Dutch Expert Committee on Occupational Safety (DECOS) limit (1.03 µg m-3 respirable EC) and the Finnish Institute of Occupational Health (FIOH) recommendation (5 µg m-3 respirable EC). Mixed-effects linear regression was used to identify determinants of EC exposure. RESULTS: In total, 149 EC samples were collected, ranging from <0.25 to 52.58 µg m-3 with a geometric mean (GM) of 3.71 µg m-3 [geometric standard deviation (GSD) = 3.32]. Overall, 41.6% of samples exceeded the FIOH limit, mostly within underground worksites (93.5%), and 90.6% exceeded the DECOS limit. Underground workers (GM = 13.20 µg m-3, GSD = 1.83) had exposures approximately four times higher than below grade workers (GM = 3.56 µg m-3, GSD = 1.94) and nine times higher than above ground workers (GM = 1.49 µg m-3, GSD = 1.75). Training facility exposures were similar to above ground workers (GM = 1.86 µg m-3, GSD = 4.12); however, exposures were highly variable. Work setting and enclosed cabins were identified as the key determinants of exposure in the final model (adjusted R2 = 0.72, P < 0.001). The highest DEE exposures were observed in underground workplaces and when using unenclosed cabins. CONCLUSIONS: This study provides data on current DEE exposure in Canadian construction workers. Most exposures were above recommended health-based limits, albeit in other jurisdictions, signifying a need to further reduce DEE levels in construction. These results can inform a hazard reduction strategy including targeted intervention/control measures to reduce DEE exposure and the burden of occupational lung cancer.

The Association between Alcohol Consumption and Breast Density: A Systematic Review and Meta-analysis.

BACKGROUND: Percent breast density (PBD) is a strong risk factor for breast cancer that is influenced by several other risk factors for the disease. Alcohol consumption is associated with an increased risk of breast cancer with an uncertain association with PBD. We have carried out a systematic review and meta-analysis to examine the association of alcohol consumption with PBD. METHODS: We searched nine databases to identify all relevant studies on the association between alcohol intake and breast density. Two independent investigators evaluated and selected 20 studies that were included in our analyses. We divided the studies into three groups according to the methods used to measure and analyze the association of breast density with alcohol consumption. RESULTS: Meta-analysis of the 11 studies that used quantitative methods to measure and analyze PBD as a continuous variable found a statistically significant difference in PBD when comparing the highest with the lowest alcohol level [ß = 0.84; 95% confidence interval (CI), 0.12-1.56]. Three studies that used quantitative methods to measure PBD and categories of PBD for analysis had a summary OR = 1.81 (95% CI, 1.07-3.04). Five studies that used categories to classify PBD and analyze their association with alcohol intake had a summary OR = 1.78 (95% CI, 0.90-3.51). CONCLUSIONS: These results suggest that there is a positive association between alcohol intake and PBD. IMPACT: Alcohol may increase the risk of breast cancer associated with PBD. Cancer Epidemiol Biomarkers Prev; 26(2); 170-8. ©2016 AACR.