Cancer Mortality in a Chinese Population Exposed to Hexavalent Chromium in Drinking Water

In 1987 investigators in Liaoning Province China reported that mortality rates for all cancer stomach cancer and lung cancer in 1970-1978 were higher in villages with hexavalent chromium (Cr/+6)-contaminated drinking water than in the general population. The investigators reported rates but did not report statistical measures of association or precision. Using reports and other communications from investigators at the local Jinzhou Health and Anti-Epidemic Station we obtained data on Cr/+6 contamination of groundwater and cancer mortality in 9 study regions near a ferrochromium factory. We estimated: (1) person-years at risk in the study regions based on census and population growth rate data (2) mortality counts based on estimated person-years at risk and previously reported mortality rates and (3) rate ratios and 95% confidence intervals. The all-cancer mortality rate in the combined 5 study regions with Cr/+6-contaminated water was negligibly elevated in comparison with the rate in the 4 combined study regions without contaminated water (rate ratio = 1.13; 95% confidence interval = 0.86-1.46) but was somewhat more elevated in comparison with the whole province (1.23; 0.97-1.53). Stomach cancer mortality in the regions with contaminated water was more substantially elevated in comparison with the regions without contaminated water (1.82; 1.11-2.91) and the whole province (1.69; 1.12-2.44). Lung cancer mortality was slightly elevated in comparison with the unexposed study regions (1.15; 0.62-2.07) and more strongly elevated in comparison with the whole province (1.78; 1.03-2.87). Mortality from other cancers combined was not elevated in comparison with either the unexposed study regions (0.86; 0.53-1.36) or the whole province (0.92; 0.58-1.38). While these data are limited they are consistent with increased stomach cancer risk in a population exposed to Cr/+6 in drinking water. (authors)