Minnesota Attorney General Lori Swanson says toxic chemicals dumped by 3M Co. in the east metro suburb Oakdale caused higher rates of cancer, infertility and low birthweight babies — the first time anyone has estimated the potential human health impact of groundwater contamination in the area since the problem came to light almost two decades ago.

In court briefs filed Friday, Swanson included the conclusions of an expert environmental witness, while alleging that the health and environmental damage of the contamination totals $5 billion and arguing that 3M should be liable for punitive damages.

The state's lawsuit against 3M, first filed in 2010, is scheduled for trial early next year after a long series of procedural delays.

The new filings detail allegations that 3M knew the local groundwater was contaminated with chemical compounds known as PFCs years before it stopped making them; that it suppressed the information over the objections of its own scientists; and that it withheld critical information from the U.S. Environmental Protection Agency (EPA).

"3M, in pursuit of profit, deliberately disregarded the substantial risk of injury to the people and environment of Minnesota from its continued manufacture of PFCs and its improper disposal," the state said.

In a statement Monday, 3M said Minnesota has not sustained any injuries, "let alone over $5 billion in alleged damages."

"3M believes these chemicals present no harm at the levels they are observed in Minnesota," said 3M's lead attorney, William Brewer III.

In a court filing the company said the lawsuit is a "misguided attempt by the State to force a responsible local corporate citizen to pay for a problem that does not exist."

3M produced PFCs, one of the most widely used chemicals in the world, for 50 years at its manufacturing plant in Cottage Grove.

The compounds were used in ScotchGuard, Teflon, degreasers and many other household and industrial products.

3M stopped producing them more than a decade ago.

But for many years, the company dumped waste containing PFCs at four sites in the southeast metro, contributing to one of the most severe and pervasive groundwater contamination problems in the state, which affected the drinking water for Lake Elmo, Cottage Grove, Oakdale, Woodbury, and St. Paul Park. 3M says all the waste disposal was legal and permitted by the state at the time.

Swanson's estimated $5 billion in total damages includes the costs of treating and replacing drinking water, the effects on fish and wildlife, and the impacts on the health of residents in the affected communities.

DFL Sen. Charles Wiger, whose district includes Oakdale, said the bottom line is that the public interest is served.

"Having access to clean water is a fundamental expectation that people have, and I know that 3M has said there are other parties that may be involved," he said. "It needs to be evaluated. I appreciate the contributions 3M has made to our area but in terms of the allegations presented here and the science, these are experts now."

"Obviously it's a very concerning issue for the citizens of Cottage Grove," the city's mayor, Myron Bailey, said Monday night.

The effects on the people of Cottage Grove are likely similar to those in Oakdale and other suburbs, Bailey said. Last May, the city turned off the wells until treatment facilities could be put in place, he said. A watering ban in the summer, while unpopular with some residents, also was an important step to protecting residents.

Bailey said the state has provided funding for two temporary treatment facilities and the city dug a new well in order to have enough fresh water free from CFEs.

With the lawsuit in progress, 3M has said it can't talk to city officials about remediation efforts, Bailey said. Cottage Grove is not a plaintiff in the lawsuit.

"We'll have to determine at some point what our position is; it might be the need for the city of Cottage Grove to go on its own" and sue 3M, he said. "Depending on how 3M reacts to our needs will determine which way as a city we'll need to go.

"With this new study...we would expect 3M to fix the issues in Cottage Grove and in other suburbs," the mayor said.

Since the lawsuit was filed, ongoing scientific research has found increasing health risks related to PFCs, including cancers and developmental impacts on children.

Now, an expert retained by the state has for the first time analyzed the frequency of potentially PFC-related health conditions in Oakdale.

David Sunding, a natural resources economist at the University of California, Berkley, and a former adviser to the EPA and President Bill Clinton, examined epidemiological data and birth and death records for Washington County and Oakdale, both before and after residents were switched to uncontaminated drinking water.

Sunding found that between 2001 and 2006, mothers in Oakdale were 34 percent more likely to give birth to a baby who weighed less than 5½ pounds; that's an average of five more low birthweight babies every year in Oakdale compared to other parts of Washington County that did not have contaminated water.

After 2006, when Oakdale residents were switched to an uncontaminated municipal system, that rate dropped to 13 percent, which he said fit with a gradual decline in the blood concentrations of the population.

Fertility was also lower among women of childbearing age from 2001-2006 — resulting in nine fewer births per year — but then improved thereafter, he said.

Cancer rates are more difficult to assess because the disease has many causes and people moved in and out of the region, Sunding said.

Nonetheless, he found similar patterns with both adult and childhood cancer cases in Washington County, the smallest geographic unit available.

Prostate cancer, for example, was 30 percent higher in Washington County than in other Minnesota counties between 2005 and 2012, he said.

In response to the growing body of research showing that the compounds have health effects, the EPA in April advised states to sharply reduce the amount of PFCs considered safe for drinking, from 300 or 400 parts per trillion down to 70.

And in May, Minnesota health officials advised cities and homeowners to adopt an even more stringent standard of 27 to 35 parts per trillion in order to reduce the long-term risks for fetuses, breast-fed infants and young children.

The health risks of PFCs were the major focus of thousands of personal injury cases in Ohio and West Virginia that DuPont and its chemical spinoff company, Chemours, settled this year for $671 million.

Staff writer Pat Pheifer contributed to this report.

Josephine Marcotty • 612 673 7394