On the Chromium Reanalysis

Smith, Allan H.

doi: 10.1097/EDE.0b013e3181a93b85
Letters to the Editor
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School of Public Health; University of California at Berkeley; Berkeley, CA; ahsmith@berkeley.edu

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The authors respond:

In response to the letter from Dennis Paustenbach, I note that my Commentary1 was confined to facts and does not contain innuendos as he claims. This response will also focus on published facts.

The real issue is whether those living near the ferrochromium factory in the Liaoning Province, China, had increased rates of cancer due to chromium contamination of their drinking water. The first publication by Zhang and Xilin Li,2 referring to the chromium polluted areas, stated that “stomach cancer mortality rates were...higher than the average for the district as a whole” for the period 1970-1978. The second publication by Zhang and ShuKun Li and written in English, stated that the “results do not indicate an association of cancer mortality with exposure.”3

Paustenbach states that I suggested “there was a reversal of scientific conclusions between the 1987 and 1997 publications of Dr. Zhang.” I did not state that, although readers can judge for themselves. He later states “it is not fairly described as a ‘reversal’,” quoting himself. The facts remain that the initial publication reported increased cancer rates in chromium-polluted areas, and the second reported that the “results do not indicate an association of cancer mortality with exposure.”

Another fact is that this second article by Zhang and ShuKun Li was retracted by the journal JOEM because “financial and intellectual input to the paper by outside parties was not disclosed.”4 In a recent publication coauthored by Paustenbach, we are informed that the payment made to Dr. Zhang was US $1960 over an 8-month period.5 We are also told that Dr. ShuKun Li, who coauthored the second paper with Dr. Zhang, stated that Dr. Zhang did not consider this “small consulting stipend” to be “worthy of mention.” A payment of $1960 over an 8-month period needs to be considered in light of urban per capita income in China at that time, which was 4288 Yuan, or about US $518 at 1995 exchange rates.6 Surely nobody would consider a payment several times the per capita annual urban income “not worthy of mention”?

This study area in China had perhaps the highest exposure to hexavalent chromium in water that will ever be experienced by a population large enough to estimate cancer rates.1 If such exposure results in elevated cancer rates, as Zhang and Xilin Li had originally suggested and as was supported by Beaumont's more detailed analysis,7 then this important information should not be obscured.

Allan H. Smith

School of Public Health

University of California at Berkeley

Berkeley, CA


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1.Smith AH. Hexavalent chromium, yellow water, and cancer: a convoluted saga. Epidemiology. 2008;19:24–26.
2.Zhang JD, Li XL. eChromium pollution of soil and water in Jinzhouf. Zhonghua Yu Fang Yi Xue Za Zhi. 1987;21:262–264.
3.Zhang JD, Li S. Cancer mortality in a Chinese population exposed to hexavalent chromium in water. J Occup Environ Med. 1997;39:315–319.
4.Brandt-Rauf P. Editorial retraction. J Occup Environ Med. 2006;48:749.
5.Kerger BD, Butler WJ, Paustenbach DJ, Zhang J, Li S. Cancer mortality in Chinese populations surrounding an alloy plant with chromium smelting operations. J Toxicol Environ Health A. 2009;72:329–344.
6.Khan AR, Riskin C. Income and inequality in China: Composition, distribution and growth of household income, 1988 to 1995. The China Quarterly. 1998;154:221–253.
7.Beaumont JJ, Sedman RM, Reynolds SD, et al. Cancer mortality in a Chinese population exposed to hexavalent chromium in drinking water. Epidemiology. 2008;19:12–23.
© 2009 Lippincott Williams & Wilkins, Inc.