Daily Environment Report, Pat Phibbs-Rizzuto
Published May 17, 2007
Hexavalent chromium caused cancer in laboratory animals that drank the chemical, the National Toxicology Program announced May 16.
"Previous studies have shown that hexavalent chromium causes lung cancer in humans in certain occupational settings as a result of inhalation exposure," said Michelle Hooth, the lead NTP scientist who summarized the programs in a technical report discussed during the May 16-17 meeting of NTP's Technical Reports Review Subcommittee.
"We now know it can also cause cancer in animals when administered orally," she said in an announcement of NTP's conclusions.
NTP's study resulted from a 2001 petition from California's Office of Environmental Health Hazard Assessment and California's Department of Health Services.
Hexavalent chromium, also known as chromium VI, is often used in electroplating, leather tanning, and textile manufacturing and has been found in some drinking water sources, NTP said as it announced the study's results.
NTP gave sodium dichromate dihydrate, which contained hexavalent chromium, to male and female rats and mice for two years at doses ranging from 14.3 milligrams per liter of water (mg/l) to 516 mg/l.
Unusual Tumors
"The researchers report finding significant increases in tumors at sites where tumors are rarely seen in laboratory animals," NTP's announcement said.
"Male and female rats had malignant tumors in the oral cavity. The studies conducted in mice found increases in the number of benign and malignant tumors in the small intestine, which increased with dose in both males and females," NTP said.
Once absorbed from the gastrointestinal tract, hexavalent chromium distributes into many tissues and organs, the program continued.
Hexavalent chromium was brought to the public's attention by the movie "Erin Brockovich." The movie showed how Brockovich's research on illnesses reported by families living in Hinkley, Calif., where Pacific Gas & Electric had released chromium VI into unlined pits contaminating drinking water, led to a $333 million settlement in 1996 and a separate settlement of $295 million to about 1,100 residents of Hinkley, Kettleman Hills, and other California towns in 2006.
In 2006, an influential study that concluded people who ingested hexavalent chromium would not face increased risk of cancer was retracted by the Journal of Occupational and Environmental Medicine (JOEM) after questions of industry funding and fraud were raised (107 DEN A-11, 6/5/06 ).
Brockovich said she is pleased that NTP's study has confirmed what many scientists told her in the 16 years she has been dealing with hexavalent chromium.
She is concerned, however, with the influence industry-funded science can have in public health discussions of a chemical's toxicities. "If industry starts buying and manipulating the science, we'll all be in trouble," Brockovich said, adding the public does not understand the extent to which industries attempt to do this.
EWG Says Study Should Prompt Reviews
Renee Sharp, a spokeswoman for the Environmental Working Group, which raised those fraud allegations, told BNA many people have long suspected hexavalent chromium would be carcinogenic when ingested because it is such a potent carcinogen when inhaled.
NTP's conclusions are important, and they should prompt California, which has been discussing a hexavalent chromium standard for many years, to finally issue one, Sharp said.
Sam Delson, a spokesman for California's Office of Environmental Health Hazard Assessment, told BNA the office will consider NTP's information as it continues to develop a draft public health goal for hexavalent chromium. He did not know when the draft standard would be released to the public; nor does the office know whether the standard would be based on hexavalent chromium's carcinogenic or noncarcinogenic effects.
Sharp said NTP's findings should spur the Environmental Protection Agency to rethink its chromium standard.
Currently, EPA regulates all forms of chromium under a single "total chromium" standard, Sharp said.
EPA's Limit Based on Noncancerous Effects
EPA's Maximum Contaminant Level is 0.1 parts per million (ppm), according to information from the agency's website. That standard is based on noncancerous effects of the chemical such as its ability to cause liver damage, harm the kidney, damage nerve tissues, and cause skin irritations.
Because hexavalent chromium is much more toxic and, now proven to be a carcinogen, when ingested, EPA should consider setting a separate standard for it, Sharp said.
EPA spokesman Dale Kemery told BNA the agency has not yet had an opportunity to review the results of NTP's study.
However, the Safe Drinking Water Act requires EPA to review each National Primary Drinking Water Regulation (NPDWR) at least once every six years and revise them, if appropriate.
EPA is evaluating its NPDWR of 0.1 mg/l (ppm) for total chromium (trivalent and hexavalent), he said.
The agency has been waiting for NTP's study, he said. Now that the NTP has released its study, "we will evaluate the results and determine whether the agency needs to update the existing health assessment," Kemery said.
The agency cannot speculate on whether it would pursue the approach Sharp recommended--the setting of a specific standard for hexavalent chromium, Kemery said.
NTP's announcement and links to additional information can be found at
http://www.niehs.nih.gov/oc/news/hexavalent.htm.
By Pat Phibbs-Rizzuto
