Lung cancer mortality and soil content of arsenic and cadmium: an ecological study in 26 EU countries

BACKGROUND: Environmental risk factors, such as exposure to air pollution, are linked with lung cancer. However, potential health impacts of exposure to carcinogenic pollutants in soil are less defined. In this ecological study, we evaluated at a regional scale potential associations between lung cancer mortality and the soil content of two carcinogens: arsenic and cadmium. METHODS: Data on deaths from lung cancer were from EUROSTAT. Soil content of arsenic and cadmium were from the Land use/cover area frame (LUCAS) 2009 survey. Analysis covered 26 EU countries and 21,035 sampling points. Three socioeconomic indicators and seven lung cancer risk factors were included. Data were linked at the NUTS2 level (n = 219) and analysed by negative binomial regression. RESULTS: After inclusion of significant predictors, the ratio of lung cancer mortality rates in the population resident in the regions within the highest quantile of arsenic concentration in soil, compared to the rest of the dataset, was 1.062 for females (95% CI 1.024 - 1.101) and 1.037 for males (95% CI 1.020 - 1.074). In the regions within the highest quantile of cadmium in soil, compared to the lower quantiles, the ratio of the mortality rates was 1.062 for females (95% CI 1.019 - 1.101) and 1.075 for males (95% CI 1.033 - 1.117). When data were stratified by land cover, significant (p < 0.05) positive associations in males were only shown for cadmium sampled from agricultural land (cropland and grassland) but not from the non-agricultural land. CONCLUSIONS: Higher rates of lung cancer mortality were reported in regions with high concentration of arsenic or cadmium in soil, relative to regions with lower concentration. Due to the ecological design, this study cannot prove causality but is in agreement with other reports linking exposure to arsenic or cadmium and lung cancer. This warrants future investigations at a finer geographical scale, focused on regions with high soil levels of arsenic and cadmium. KEY MESSAGES: • Higher lung cancer mortality rates were reported in regions with high concentration of arsenic or cadmium in soil, relative to regions with their lower concentration. • There was an association between cadmium in soil and lung cancer mortality in males for the subset of sampling points from the agricultural land but not for the non-agricultural land.