Project Type

Faculty Scholarship

Scholarship Domain(s)

Scholarship of Discovery

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Presentation

Abstract

Cr(VI) (hexavalent chromium) has recently been found in the drinking water of over 250 million Americans. It is a powerful oxidizing agent, and is known to cause cancer, although the specific mechanism has yet to be elucidated. There is no known preventative treatment for Cr(VI) exposure, and the US EPA is currently determining what concentration of Cr(VI) in drinking water can be safely tolerated. This study sought to test the hypothesis that Cr(VI) cytotoxicity can be prevented by various antioxidants. We tested this hypothesis by exposing human embryonic kidney and human intestinal epithelial cells to Cr(VI), with and without the presence of the antioxidants vitamin C, or epigallocatechin gallate (EGCG). Cr(VI) was found to be significantly toxic to human cell cultures at concentrations of 200 parts per billion (ppb) and higher. This effect was blocked by 10 parts per million (ppm) vitamin C and by 15 ppm EGCG. No cytotoxic effects were observed on cells treated with vitamin C or EGCG alone. We also used an Ames test to determine if these antioxidants can prevent Cr(VI)-induced mutagenesis on bacterial cells. The Ames test revealed that Cr(VI) causes DNA mutations in bacterial cells at concentrations of at least 20 ppb. This effect was blocked by 20 ppm vitamin C. No mutagenic effect was observed with vitamin C alone. Taken together, the results suggest that Cr(VI) is toxic to human cells through an oxidative mechanism at a concentration of at least 200 ppb. Additionally, Cr(VI) may also cause DNA mutations at concentrations of 20 ppb or more. These effects can be abrogated with antioxidant co-treatment. While further study is merited, these results should help to inform government agencies tasked with monitoring drinking water quality.

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Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.

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Hexavalent Chromium: Elucidating its Carcinogenic Mechanism, and Testing Potential Preventative Treatments

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Cr(VI) (hexavalent chromium) has recently been found in the drinking water of over 250 million Americans. It is a powerful oxidizing agent, and is known to cause cancer, although the specific mechanism has yet to be elucidated. There is no known preventative treatment for Cr(VI) exposure, and the US EPA is currently determining what concentration of Cr(VI) in drinking water can be safely tolerated. This study sought to test the hypothesis that Cr(VI) cytotoxicity can be prevented by various antioxidants. We tested this hypothesis by exposing human embryonic kidney and human intestinal epithelial cells to Cr(VI), with and without the presence of the antioxidants vitamin C, or epigallocatechin gallate (EGCG). Cr(VI) was found to be significantly toxic to human cell cultures at concentrations of 200 parts per billion (ppb) and higher. This effect was blocked by 10 parts per million (ppm) vitamin C and by 15 ppm EGCG. No cytotoxic effects were observed on cells treated with vitamin C or EGCG alone. We also used an Ames test to determine if these antioxidants can prevent Cr(VI)-induced mutagenesis on bacterial cells. The Ames test revealed that Cr(VI) causes DNA mutations in bacterial cells at concentrations of at least 20 ppb. This effect was blocked by 20 ppm vitamin C. No mutagenic effect was observed with vitamin C alone. Taken together, the results suggest that Cr(VI) is toxic to human cells through an oxidative mechanism at a concentration of at least 200 ppb. Additionally, Cr(VI) may also cause DNA mutations at concentrations of 20 ppb or more. These effects can be abrogated with antioxidant co-treatment. While further study is merited, these results should help to inform government agencies tasked with monitoring drinking water quality.