DEP challenges findings on tungsten toxicity

Army researchers say exposure to low levels of tungsten has no negative impact on the health of rats.

State environmental officials aren't so sure.

The state Department of Environmental Protection has asked Army toxicologists to reconsider the conclusions of a recent toxicity study on the metal, which has been found in the Upper Cape's drinking water aquifer.

The so-called environmentally friendly tungsten-nylon ammunition was fired at Camp Edwards until last year, when it was found beneath the base in the aquifer that serves as the Upper Cape's primary source of drinking water.

In a report released publicly late last year, Army researchers at the U.S. Center for Health Promotion and Preventive Medicine found that rats suffered kidney damage and weight loss after drinking tungsten-tainted water.

Army researchers also found changes in the blood chemistry of the rats, but determined these were either not significant or were not adverse effects.

In a letter sent to the Army researchers this week, reviewers from the DEP Office of Research and Standards disagreed with the Army's conclusions about the lowest dose that had a negative effect on health.

DEP reviewers also asked the Army not to disregard some of the results, as they might be important to the root of tungsten's potential toxicity.

Tungsten's toxicity to humans is not well understood, but animal research shows it can lower fertility and may increase the cancer-causing potential of other substances, such as other heavy metals.

An Army spokeswoman would not comment on the specifics of the DEP's letter, but said some of the questions may be answered in a second Army-funded tungsten study now under way.

"We're happy to work with Massachusetts state regulators ... and are considering carefully our response to their letter," said Army spokeswoman Lyn Kukral.

The Army commissioned the tungsten study in 2004 in light of problems with the tungsten-nylon bullets. The bullets were supposed to be a nonpolluting alternative to toxic lead bullets but tungsten was found to leach into some soil types.

Last year, Gov. Mitt Romney stopped the use of the tungsten-nylon bullet on the Upper Cape military reservation after tungsten was found to have leached into the groundwater at concentrations as high as 560 parts per billion. One part per billion is equivalent to a half a teaspoon in an Olympic-size swimming pool.

Recent testing at the base shows one new well with a trace amount of tungsten.

The Army's tungsten study was meant to simulate how people may be exposed to the metal through drinking water.

Researchers fed the rats doses of tungsten-saturated water ranging from 0.2 200 milligrams of tungsten for every kilogram of the rat's body weight.

They concluded that the dose of 200 milligrams per kilogram of weight was the lowest level to cause adverse health effects in rats. Regulators use a level such as this to decide what amount of a substance in water is safe to drink.

The DEP reviewers took exception to the Army researcher's conclusion, noting that the research found some adverse health effects at lower doses, including a reduction in bilirubin, which is produced when red blood cells break down, and an increase in lymphocytes, or the white blood cells that are key to the immune system.

The Army researchers concluded the bilirubin and lymphocyte levels were within normal ranges. But the DEP reviewers said data indicate bilirubin levels are important to prevent cellular damage, and the decreased bilirubin levels should not be disregarded, according to the DEP letter.

And since, as Army researchers point out in their work, increased lymphocytes can be a sign of viral infection and may be associated with leukemia, further research into those effects should be conducted, DEP reviewers suggested.

Some animals even died at the 200 milligram dose, suggesting it was a very toxic level, according to the DEP letter.

"We saw some changes in the blood and in the kidney that we had some questions and concerns about. These effects were at doses lower than the 200 milligram per kilogram," said Carol Rowan West, director of the DEP's Office of Research and Standards.

A follow-up to the Army's original research is under way to help better determine what level of tungsten is safe to drink. Kukral said it will likely take several more months for the data to be reviewed.

DEP officials said they will continue to review new research on tungsten to see whether a safe drinking water standard should be established, since there are currently no state or federal standards. Although there is now tungsten in the aquifer, it has not reached any of the area public drinking water supply wells.

"Since no one is exposed, we have not rushed down that path," said Mark Smith, deputy director for the DEP's Office of Research and Standards.

"We don't have any hits in the public water supplies," Rowan West said. "If we had to act, we have all the data."

Amanda Lehmert can be reached at alehmert@capecodonline.com.