March 5, 2007: Should you drink the tap water?

It's the question John Linc Stine expects every time he answers the phone or attends a public meeting. "Would you drink the water?"

It's also the hardest one to answer.

Stine, environmental health division director at the Minnesota Department of Health, cannot give a simple answer, and he knows that irritates people.

The question has arisen frequently in the past several weeks after a chemical formerly manufactured by 3M Co. was detected in city water supplies of six east metro communities. Even before that, two different 3M chemicals showed up in the public wells of Oakdale and private wells in Lake Elmo.

Last week, on the basis of recent research into the chemicals' toxicity, the Health Department lowered its recommended maximum concentrations of two compounds, PFOA and PFOS, in drinking water. Many of the concentrations found in the wells are near what health officials still consider to pose little or no risk.

In those situations, Stine said that he cannot answer the question about drinking water with a yes or no, because either answer could be misconstrued.

To answer "yes" could be interpreted as an endorsement that the water is safe, and Stine said he doesn't know that. The 3M chemicals, known as perfluorochemicals, are not an immediate cause for concern in drinking water, he said, but health officials do not know about risks from long-term exposure.

To answer "no" would be interpreted as a declaration that the water is dangerous, and Stine said he doesn't know that either, at least for people who might have drunk the water for years. Scientists have learned about some of these chemicals only recently, he said, and didn't have the ability to test for low levels of one chemical, PFBA, in Minnesota until last year.

What is known about perfluorochemicals is that they do not change or break down in the environment, and one of them, PFOA, is considered a likely carcinogen by a federal advisory panel.

Stine tells those who call him that they need to make their own decision about drinking the water and that he can only provide information about the chemicals for people to evaluate.

3M has also realized that the public is concerned about health risks and added information about the chemicals last week to a company Web page. "Hearing of any material being present in your water, we understand that that can raise questions," said 3M spokesman Bill Nelson.

The company wants to put the risks into context, he said, and to reaffirm in greater detail its previous contention that the drinking water is safe.

Health officials will never say that something is safe, said Will Hueston, director of the Center for Animal Health and Food Safety at the University of Minnesota. Hueston, an expert on communicating about risks, said that the dictionary meaning of "safe" means "absence of risk," and that nothing in life is risk-free.

"That having been said, your operating definition of safety might be much different than mine," Hueston said. "If I gather 10 people and put them in a room and gave them identical scientific information, there'd be 10 different levels of risk perception."

Hueston gives the Health Department high marks for being direct and honest with the public about the contaminated water. "Tell the people what you know, what you don't know, what you're doing to find out more, when you'll get back to them and the options of what they can do with the knowledge that we currently have," he said.

Perfluorochemicals have been found in the blood of people and wildlife across the globe. Some of them accumulate in human blood, and others do not. PFBA, found widely in the groundwater in the east- metro area, has not been studied much. Environmental Protection Agency scientists are now studying mice dosed with PFBA to determine whether the chemical affects birth and development.

Jim Kelly, risk assessor for the Minnesota Department of Health, said that studies of rats exposed to high levels of PFBA show some effects on the liver.

More is known about two other chemicals, PFOA and PFOS, that 3M manufactured until 2002 and disposed of in three metro-area dumps between 1956 and 1974. PFOA and PFOS accumulate in human blood, Kelly said, and unlike other chemicals do not appear to concentrate in particular tissues or organs. Laboratory animals exposed to high doses of PFOS have died, Kelly said, and at lower doses they have shown enzyme changes or increased weights in livers.

PFOA at high doses has caused liver and other cancers in rats, Kelly said.

The Health Department analyzes those studies and other information, he said, and adds extra measures of protection to come up with its recommended maximum concentrations. Those are levels of a chemical in water that health officials consider to be virtually risk-free over a lifetime of drinking the water.

Under the recommendations announced last week, the maximum concentration for PFOS is 0.3 parts per billion (ppb), and PFOA is 0.5 ppb. The level for PFBA remains at 1 ppb.

Nelson, the 3M spokesman, said that most of the laboratory animal studies have shown health effects only at very high doses and that the chemicals do not pose human health risks at the levels they've been detected in drinking water in Minnesota. 3M has monitored the health of thousands of its employees over the past 25 years who worked directly with PFOA, Nelson said, and has found "no association between their exposure and any adverse health effects."

Stine said that there are more questions than answers about the potential human health risks from perfluorochemicals. He said it takes time and money to learn about the effects of chemicals, especially at relatively low levels over long periods of time.

"Right now, people are affected by their fears and by their emotions, and it doesn't help them to say that we're working as fast as we can," said Stine. "Yet you have to rely upon the science to give you the best advice because otherwise we're simply acting on the basis of our opinions."

Tom Meersman • 612-673-7388 • meersman@startribune.com