Cancer Mortality in Chinese Populations Surrounding an Alloy Plant with Chromium Smelting Operations

Abstract

This report is a further characterization of data from an ecological cancer mortality study of a population (about 10,000) exposed to groundwater contaminated by hexavalent chromium [Cr(VI)] up to 20 mg/L near JinZhou City in the LiaoNing Province of China between 1960 and 1978. Prior reports showed an elevation in all-cancer mortality from 1970 to 1978 averaged across five agricultural villages with Cr(VI) in groundwater relative to average cancer rates for the district and province. The current study compares the cancer rates during the same time period for the same five exposed villages to those of four nearby areas with no Cr(VI) in groundwater. The use of a local comparison group is considered superior to the use of district or province averages because of the expected improved similarity among unmeasured covariates in nearby areas. The average lung-, stomach-, and all-cancer mortality rates for the three agricultural villages without Cr(VI) in groundwater were not statistically different from those of the five agricultural villages with Cr(VI) in groundwater. Also, three surrogate measures of village drinking-water Cr(VI) dose did not significantly correlate with cancer mortality rates in the five exposed villages. Further, the industrial town in which the Cr(VI) source was located had different demographics and a different pattern of stomach and lung cancers compared to the adjacent agricultural villages, regardless of Cr(VI) groundwater exposure. The results of other local investigations on cancer mortality and genotoxicity in the exposed populations are reviewed. The overall findings in the studied population do not indicate a dose-response relationship or a coherent pattern of association of lung-, stomach-, or all-cancer mortality with exposure to Cr(VI)-contaminated groundwater.

JianDong Zhang is deceased; his work is submitted posthumously by Dr. Li.

The mortality study upon which this report and the earlier reports are based (Zhang & Li, 1980, 1987) was funded solely by the government of China prior to 1987, through the JinZhou Disease Control and Prevention Station and other government entities in the region. The additional analysis of the original data in this article is based on reports that were written by Dr. Zhang prior to 1987. In 1995–1996, the authors received funding from Pacific Gas and Electric Company (PG&E) to study the JinZhou pollution incident and to provide the more detailed statistical analyses of the original data as presented in Tables 1, 2, and 4. After 1996, none of the authors received outside funding for their preparation of this article. This article does not necessarily represent the views of the government agency employers of Dr. Zhang or Dr. Li. Drs. Kerger, Butler, and Paustenbach have been independent scientific consultants for clients with chromium contamination issues in regulatory or litigation settings. The authors acknowledge Tony Ye for technical assistance, and the five peer reviewers for their time and valuable insights.

Notes

California Environmental Protection Agency. 2005b. Peer review comments on the 2005 draft public health goal for chromium (3 peer reviews of the 2005 draft document by Bjeldanes, L, Gwiazda, R., and Kelner, M.J.). California Environmental Protection Agency, Office of Environmental Health Hazard Assessment. Available at http://oehha.ca.gov/water/phg/pdf/ThreeCr6review.pdf or at http://www.chemrisk.com/public/Zhang

Waldman, P. 2005. Study tied pollutant to cancer; Then consultants got hold of it. Wall Street Journal, December 23, 2005. Responses of Paustenbach, D., Kerger, B., and Butler, J., in Wall Street Journal, letters, January 20, 2006.