Mice and rats were exposed to four different doses, and they contracted cancer at lower levels than in the 1968 study, according to Michelle Hooth, a toxicologist at the National Institute of Environmental Health Sciences who was the study’s lead scientist. In addition, chromium caused mouth cancers, and infiltrated the cells of many organs, including livers and pancreatic lymph nodes. “Since they found tumors in the small intestine, that shows it was not eliminated in the stomach,” Alexeeff said.Ĭancer in the small intestine is “relatively rare” in animals, even those exposed to other chemicals, the scientists reported. The study, published online in Environmental Health Perspectives in December, shows that although some of the substance is reduced in the stomach to Chromium III, it’s not enough to avoid toxic effects. The debate focused on whether hexavalent chromium is neutralized in the stomach by gastric acids that turn it into Chromium III, an essential nutrient.Ĭalifornia officials, seeking to resolve the controversy, asked the National Toxicology Program to conduct animal tests.
#Chromium in drinking water skin
California’s scientific advisors agreed, so the state rescinded its goal in 2001 and reverted to the 50 ppb standard, which was adopted in 1977 and based on the risks of skin irritation, not cancer. EPA rejected that study as flawed and determined there was no evidence it was carcinogenic in water. It was based on a 1968 study in Germany that found stomach tumors in animals that drank the substance. In 1999, after the Hinkley case, California set a water guideline, called a Public Health Goal, of 2.5 ppb. The national standard is 100 ppb.īecause of the cancer uncertainty, California has had a tumultuous history of setting water standards to protect people from chromium. Hinkley’s ground water contained concentrations as high as 580 parts per billion, more than 10 times California’s current drinking water standard of 50 ppb for total chromium compounds. However, Gwiazda said, using the new research “to support a drinking water standard is a different matter” because extrapolating it to humans remains controversial. Roberto Gwiazda, an assistant researcher at University of California at Santa Cruz’s Department of Environmental Toxicology, called the new study a “milestone,” saying it “settles the issue.” But it does resolve the debate over whether the contaminant is capable of causing some types of cancer. The animal study does not prove that people in Hinkley contracted cancer from drinking the tainted water. The payment was the largest tort injury settlement in U.S. The town's plight drew national attention in 2000 from a film based on Brockovich's legal crusade. In 1996, PG&E paid a $333 million settlement to about 600 residents of Hinkley after Brockovich, a law clerk, investigated the contamination and found high rates of cancer and other diseases. The compound seeped into water there from a Pacific Gas and Electric facility that used it to inhibit rust in cooling towers and discharged it into holding ponds in the 1950s and 1960s. The Mojave Desert town of Hinkley, population of around 1,900, has the highest levels of hexavalent chromium reported in U.S. Within a few weeks, California is expected to announce a proposal to set a new health guideline. Environmental Protection Agency officials are reevaluating what concentration is safe in water supplies.
“I think it’s resolved, as much as it can be resolved,” said George Alexeeff, deputy director of scientific affairs at California’s Office of Environmental Health Hazard Assessment.īased largely on the new cancer findings, California and U.S. Mice and rats contracted malignant tumors in their small intestines and mouths when they drank water containing several different doses of hexavalent chromium. National Toxicology Program scientists reported that their two-year animal study “clearly demonstrates” that the compound is carcinogenic in drinking water. But until now, toxicologists have been uncertain whether it causes cancer when swallowed. It’s been known for about 20 years that people can contract lung cancer when inhaling hexavalent chromium, also known as Chromium VI. That conclusion by federal scientists, culminating more than a decade of debate, is likely to trigger new, more stringent standards limiting the amount of hexavalent chromium allowable in water supplies.
A controversial water contaminant made famous by Erin Brockovich and a small California desert town is carcinogenic.
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