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Protecting the Public from Hexavalent Chromium in Drinking Water

Laboratory science and environmental policy combine to provide critical insights to protect human health


To analyze chromium distribution in in vivo studies to understand the toxic effects of hexavalent chromium


We used specialized equipment, methods, and expertise to determine how hexavalent chromium from drinking water is distributed throughout the body.


The results provided by RTI helped the National Toxicology Program establish that hexavalent chromium is a harmful carcinogen in drinking water. These findings were integrated into human cancer risk models that have influenced policies around hexavalent chromium in drinking water and have helped establish state and federal drinking water limits in the United States.

Exposure to hazardous chemicals can impact human health and quality of life. Environmental policies designed to minimize chemical exposure and protect public health are based on a range of information, including toxicity and how often and how much of a chemical can be found in the environment. Laboratory measurements of environmental and biological samples help to protect public health by increasing our understanding of chemical exposures.

Investigating A Widespread Contaminant in Drinking Water

In 2001, following a series of highly-publicized exposure clusters (including the one depicted in the movie, Erin Brokovich), the National Toxicology Program received a nomination to study the potentially toxic effects of hexavalent chromium in drinking water. These studies included in vivo models to understand both how much hexavalent chromium was taken up from drinking water and where it was distributed in the body.

A 2016 study by the Environmental Working Group (EWG) indicated that hexavalent chromium is more common in drinking water than was previously thought, estimating that as many as 218 million Americans could be served by water systems with detectable hexavalent chromium, either from manmade or natural sources.

RTI has been a trusted partner of the National Toxicology program through its Chemistry Services Contract since 1984. Our laboratory experts provide support to the program for a range of services including formulation development, chemical procurement, and bioanalytical services.

Our analytical laboratories helped the National Toxicology Program understand the distribution of hexavalent chromium from drinking water by measuring chromium in several tissues, including the kidney, liver, bones, blood, intestines, and others. We used our suite of specialized laboratory instruments and facilities and over 100 combined years of experience in bioanalysis to design and validate a comprehensive set of analyses for each type of sample. These robust, scientifically-defensible measurements helped the National Toxicology Program establish where in the body different forms of chromium in drinking water were taken up by our test subjects.

Our data were included in the analysis of cancer occurrence, which found that hexavalent chromium is carcinogenic when consumed in drinking water. Test subjects dosed with hexavalent chromium exhibited oral cancer and cancer of the small intestine, which are not common cancers, and combined with our biodistribution results, suggested that the chromium was the cause of the cancer.

In the years after the publication of that report, EPA concluded that a review of the previous drinking water limit for chromium was necessary, a process that is still under way. However, considering the reported results, in 2014, California became the first state in the country to set a drinking water limit for hexavalent chromium of 10 parts-per-billion (ppb), with a contaminant goal of 0.02 ppb.

As the discussion around the regulation of chromium exposure continues, we will continue to play a role in providing scientific facts to support policy decisions.