Cancer incidence attributable to air pollution in Alberta in 2012

Abstract

Background:The International Agency for Research on Cancer has classified outdoor air pollution (fine particulate matter [PM 2.5 ]) as a Group 1 lung carcinogen in humans. We aimed to estimate the proportion of lung cancer cases attributable to PM 2.5 exposure in Alberta in 2012.Methods: Annual average concentrations of PM 2.5 in 2011 for 22 communities across Alberta were extracted from the Clean Air Strategic Alliance Data Warehouse and were population-weighted across the province. Using 7.5 µg/m 3 and 3.18 µg/m 3 as the annual average theoretical minimum risk concentrations of PM 2.5 , we estimated the proportion of the population above this cut-off to determine the population attributable risk of lung cancer due to PM 2.5 exposure. Results:The mean population-weighted concentration of PM 2.5 for Alberta in 2011 was 10.03 µg/m 3 . We estimated relative risks of 1.02 and 1.06 for theoretical minimum risk PM 2.5 concentration thresholds of 7.5 µg/m 3 and 3.18 µg/m 3 , respectively. About 1.87%-5.69% of incident lung cancer cases in Alberta were estimated to be attributable to PM 2.5 exposure.Interpretation: Our estimate of attributable burden is low compared to that reported in studies in other areas of the world owing to the relatively low levels of PM 2.5 recorded in Alberta. Reducing PM 2.5 emissions in Alberta should continue to be a priority to help decrease the burden of lung cancer in the population. AbstractSee also www.cmajopen.ca/lookup/doi/10.9778/cmajo.20150068each 10-µg/m 3 increase in concentration of PM 10 exposure, the hazard ratio for all lung cancer types was 1.22. Those authors also completed analyses for subtypes of lung cancer, where exposure to PM 2.5 was examined in increments of 5 µg/m 3 , with a hazard ratio of 1.55 for adenocarcinomas. These analyses are of particular interest as a higher proportion of adenocarcinomas develop in nonsmokers, and therefore nonsmokers represent a population of interest when examining risk factors other than smoking. 7In Alberta in 2012, lung cancer accounted for 12% of all incident cancers, 8 making it the third most frequently diagnosed cancer. Although smoking is known to be the main cause of lung cancer, it is relevant for public health efforts to explore other risk factors for lung cancer. In the present study, we used population attributable risk estimates to estimate the proportion and absolute number of incident lung cancer cases attributable to PM 2.5 exposure in Alberta in 2012. MethodsThis manuscript is part of a series of exposure-specific manuscripts concerning the proportion of cancer cases attributable to modifiable lifestyle and environmental risk factors in the general population of Alberta. The methodologic framework for this series has previously been described. Prevalence of exposureWe extracted average concentrations of PM 2.5 for 22 communities with complete data in Alberta for 2011 from the Clean Air Strategic Alliance Data Warehouse (now the ambient air quality data warehouse).10 The PM 2.5 concentration data from these communitie...

An approach to estimating the environmental burden of cancer from known and probable carcinogens: application to Ontario, Canada

“…We estimated a PAF of 5.8% (90% PI: 3.0 to 9.4%) for lung cancer cases attributable to PM 2.5 exposure in Ontario. This estimate was comparable to air pollutionlung cancer PAFs of 1.9 to 5.7% reported for Alberta, Canada in 2012 [48] and 7.8% reported for the United Kingdom in 2015 [8]. Although the PAF reported for the United Kingdom was based on the same relative risk from Hamra et al [27] we used in our study, the Alberta PAF reflected levels above 7.5 or 3.2 μg/m 3 and was based on older risk estimates [49,50].…”

Burden of cancer attributable to air pollution in Japan in 2015

“…On the other hand, a recent study in Canada, where air pollution levels are much lower than in Japan, estimated that 2-6% of incident lung cancer cases in 2012 might have been attributable to PM 2.5 exposure by applying different reference levels of PM 2.5 (7.5 μg/m 3 and 3.18 μg/m 3 , respectively) (44). In the GBD study, the fraction of lung cancer mortalities attributable to PM 2.5 was estimated to be 8.6% in Western Europe and 4.6% in the US (25).…”

Cancer incidence attributable to lifestyle and environmental factors in Alberta in 2012: summary of results

“…We give comparisons between the UK and Alberta populations at the exposure-specific level in our previous articles. [2][3][4][5][6][7][8][9][10][11] In Australia, about 32% of cancers in 2010 were estimated to be attributable to 13 modifiable factors. 29 This estimate is lower than both our estimate for Alberta and the UK estimate.…”

“…1 As some factors were considered protective for cancer and others were cancer risk factors, Table 1 summarizes what we consider to be the theoretical minimum risk level of exposure for each lifestyle and environmental factor based on our research (unpublished data). [2][3][4][5][6][7][8][9][10][11] We estimated the total number of cancer cases attributable to the 24 risk factors by summing the number of cases of cancer at individual sites attributable to each individual exposure. Additional methods for the exposures included in this summary paper but not presented in separate exposure-specific papers are presented in Appendix 1, available at www.cmajopen.ca/ content/5/3/E540/suppl/DC1.…”