Cancer incidence and high environmental arsenic concentrations in rural populations: results of an ecological study

A number of ecological studies have suggested associations between arsenic in drinking water and increased rates of some cancers. To investigate assoc iations in areas with high environmental arsenic concentrations, geographic al areas with surface soil inorganic arsenic concentrations of > 100 mg/kg and! or drinking water arsenic concentrations > 0.01 mg/l were selected and the relationship with cancer incidence explored. Standardised incidence ra tes (SIRs) for cancer were generated for 22 areas between 1982 and 1991 usi ng Victorian Cancer Registry data and Victorian cancer rates as a baseline. SIRs were also generated for combined areas according to environmental exp osure type, i.e, whether an area had high soil and/or high water arsenic co ncentrations. The SIRs for both males and females for the combined 22 areas were increased for all cancers 1.06 (95% confidence interval, CI; 1.03-1.0 9), prostate cancer 1.14 (1.05-1.23), kidney cancer 1.16(0.98-1.37), melano ma 1.36(1.24-1.48), chronic myeloid leukemia 1.54 (1.13-2.10) and breast ca ncer in females 1.10(1.03-1.18). When stratifying into exposure categories, the SIR for prostate canter was significant at 1.20(1.06-1.36) for the hig h soil/high water category only. No significant dose - response relationshi p between drinking water and individual cancers was observed. Of the a prio ri cancers associated with environmental arsenic exposure, only prostate ca ncer incidence was significantly elevated in this study. This result was li kely confounded by a number of factors and was limited by low power and exp osure misclassification.