Hexavalent Chromium + Vitamin C = Cancer

Hexavalent Chromium + Vitamin C = Cancer

PROVIDENCE, Rhode Island, (ENS)

12th March 2007

Even tiny amounts of hexavalent chromium can cause cancer, and Brown University researchers have found a connection between that effect and the nutrient vitamin C.

Naturally occurring vitamin C reacts inside human lung cells with chromium 6, or hexavalent chromium, and causes massive DNA damage, researchers found.

Low doses of chromium 6, combined with vitamin C, produce up to 15 times as many chromosomal breaks and up to 10 times more mutations - forms of genetic damage that lead to cancer - compared with cells that lacked vitamin C altogether.

This finding is startling, said Anatoly Zhitkovich, an associate professor of medical science at Brown who oversaw the experiments, funded by the National Institutes of Health.

Outside cells, Zhitkovich said, vitamin C actually protects against the cellular damage caused by hexavalent chromium, the toxic chemical that starred as the villain in the Hollywood drama, "Erin Brockovich."

This is the toxic metal, found in drinking water in a small California town, that Erin Brockovich campaigned against, successfully winning residents a record settlement of $333 million in 1996.

Vitamin C is a powerful antioxidant, blocking cellular damage from free radicals. Specifically, the vitamin rapidly "reduces," or adds electrons, to free radicals, converting them into harmless molecules. This electron transfer from vitamin C to chromium 6 produces chromium 3, a form of the compound that is unable to enter cells.

Vitamin C has been used as an antidote in industrial accidents and other instances when large amounts of chromium are ingested.

But when chromium and vitamin C come together inside cells Zhitkovich and his team found that vitamin C acted as a potent toxic amplifier, sparking more chromosomal breaks and cellular mutations.

"When we increased the concentration of vitamin C inside cells, we saw progressively more mutations and DNA breaks, showing how seemingly innocuous amounts of chromium can become toxic," Zhitkovich said. "For years, scientists have wondered why exposure to small amounts of hexavalent chromium can cause such high rates of cancer. Now we know. It's vitamin C."

Hexavalent chromium is used to plate metals and to make paints, dyes, plastics and inks. As an anticorrosive agent, it is also added to stainless steel, which releases hexavalent chromium during welding.

Hexavalent chromium causes lung cancer and is found in 40 percent of Superfund sites nationwide.

Zhitkovich said his team's research, published in "Nucleic Acids Research," might have policy implications. When combined with vitamin C, chromium 6 caused genetic damage in cells in doses four times lower than current federal standards, Zhitkovich said. If additional research backs these findings, he said federal regulators might want to lower exposure standards.