The Big Story Blog

Fish, perfluorochemicals and health

Posted at 3:24 PM on October 13, 2011 by Paul Tosto
Filed under: Environment

So, how much will it take to kill me?

Really, that's the operative question when it comes to the release of chemicals into the environment. We know the benefits of industrial production come with costs. We just don't want them to damage or kill us.

The discharge of perfluorochemicals (PFCs) in the Mississippi River between St. Paul and Hastings is the target of new limits by the Minnesota Pollution Control Agency and a potential lawsuit against 3M by the Metropolitan Council, a story we've been following today.

The health research isn't conclusive. The science shows it's a potential carcinogen. Elevated levels of the chemicals have surfaced in the bloodstreams of 3M workers. But as the State Health Department and 3M say, there's no data showing a direct link between PFCs and human health problems.

But what's the data tell us about the fish we eat that absorb PFCs?

Fish. In the PFC family, Perfluorooctanesulfonic acid, or PFOs, tend to show up in the fish in the stretch of the Mississippi River between the Ford Dam at St. Paul and the dam just above Hastings. MPCA testing in 2009 found the chemical compound in all the fish it tested there.

Is that bad? The State Health Department notes:

Some areas of the Mississippi River, several metro area lakes and a couple of lakes near Duluth have been tested for PFCs. PFOS is the only PFC that accumulates to levels of concern in fish.

Most fish, even in these areas have low levels of PFOS, so that the Minnesota Department of Health (MDH) Fish Advisory recommends unrestricted consumption or one meal per week for many species.

Four metro area lakes, however, showed PFO levels requiring more restrictive advice of only one fish meal per month. Those are Twin Lakes, Calhoun, Johanna and Lake Elmo.

The bigger concern is what happens when people keep eating the fish.

"It all comes down to the fact that we have to protect to a level that won't cause risk in humans that consume the fish," the Pollution Control Agency's Katrinia Kessler told MPR News reporter Stephanie Hemphill.

"And epidemiology shows that bio-accumulation happens in fish and then in people that consume the fish in such a way that we need to have the effluent be at no greater than what we are proposing for the Met Council."

Hemphill also reports that in April, Met Council staff told members of the environment committee that it makes sense to clean up the sediment near the Cottage Grove plant, and then test the fish to see if there is less PFC in their tissue. Hemphill adds:
3M spokesman Bill Nelson says that sediment cleanup should be done this winter. But the company continues to send PFC-laden water into the river. The company does not have a time line for its plan to upgrade its Cottage Grove water treatment plant.

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About Paul Tosto

Paul Tosto

Paul Tosto writes the Big Story Blog for MPR News. He joined the newsroom in 2008 after more than 20 years reporting on education, politics and the economy for news wires and newspapers across the country.