High levels of PFOS, formerly made by 3M, have been found in the blood of Mississippi River fish, raising questions about potential risks.
Minneapolis Star Tribune, Tom Meersman
Published February 25, 2006
Don Kriens, principal engineer for the Minnesota Pollution Control Agency (MPCA), couldn't believe his eyes when he saw the results. Blood samples taken from fish in the Mississippi River near the 3M plant in Cottage Grove showed very high levels of PFOS, a chemical manufactured at the plant until 2002 and used in stain-resistant treatments for carpets, fabrics and paper products.
"The results were startlingly high," Kriens said, with some chemical concentrations 10 times higher than had been reported anywhere for fish or wildlife. "The fish are definitely contaminated with this stuff," he said.
State health officials who reviewed the results said that because the chemicals were found in fish blood, which people do not consume, there is no way to determine potential health risk for humans. Jim Kelly, health assessor for the Minnesota Department of Health, said he hopes to learn much more after fish fillets from the study have been analyzed.
"At this point I don't see this as a big looming health threat, but it certainly bears more investigation," Kelly said.
Anglers who fish in that part of the river are already advised not to eat more than one meal per month of some species, he said, because of mercury and PCB contamination.
However, some legislators are concerned about the 3M chemicals, and the Senate environment and natural resources committee has scheduled a hearing on the matter for Monday.
The MPCA findings are a red flag for natural resource officials, because wildlife consume fish blood as well as flesh and internal organs. "We have bald eagles and kingfishers and diving ducks and all kinds of wildlife that eat fish in that stretch of the river," said Jack Enblom, senior aquatic biologist for the Minnesota Department of Natural Resources (DNR).
The results also open a new chapter on where PFOS and related chemicals, produced for decades at the Cottage Grove plant, were discharged or disposed. Many of them do not break down in the environment and they can accumulate in humans. Until now, local monitoring has detected them primarily in groundwater near former landfills. Now the focus has broadened to include the river.
Bill Nelson, a 3M spokesman, said the company hasn't seen the MPCA data. He said 3M took fish near the plant last August for study, and is preparing a report for state officials.
Autumn fishing
The MPCA researchers worked with the DNR to collect about 100 fish last October at various points along a 1.5-mile segment of the river downstream from the Cottage Grove plant. They took blood samples from about two dozen of the larger fish species and sent them to a lab to analyze levels of PFOS and a dozen related compounds.
Fardin Oliaei, an MPCA researcher who worked with Kriens on the project, said the test included five white bass, six smallmouth bass, five walleyes, five carp, and one smallmouth buffalo. PFOS in the blood ranged from a low of 139 parts per billion in one of the walleyes to 29,600 parts per billion in one white bass, she said.
Oliaei has criticized the MPCA for not being aggressive enough in researching the 3M chemicals, filed a federal whistleblower lawsuit alleging interference with her work, and left the agency early this month as part of an out-of-court settlement.
The state health department does not have any values on how much PFOS in fish blood or fish tissue would be safe for wildlife or human consumption. It recommends that PFOS levels in drinking water be no higher than 1 part per billion.
Scientific debate
Last month, the Environmental Protection Agency called for elimination of PFOA, a different chemical in the same family that 3M manufactured before 2000 and sold to firms making nonstick cookware and other products. On Feb. 15 an EPA scientific advisory panel, against 3M objections, recommended that PFOA be deemed a likely human carcinogen. PFOS doesn't have that status, but more federal review of its potential health risks is expected.
Animal lab studies have linked exposure to PFOS with certain cancers, liver damage and developmental problems.
However, 3M spokesman Nelson said that extensive research, some of it involving 3M production workers who worked closely with PFOS and PFOA for years, has shown no adverse health effects in humans. He said that the company has coordinated its research plans and shared results with state officials. And he said that 3M successfully phased out the production of the chemicals and has replaced them with other compounds.
Kriens and Oliaei said their findings raise questions about how PFOS moves through the food chain, accumulates in fish and other aquatic organisms, spreads in a river system, or is stored in sediment. Kriens has also received fish from Lake Pepin further downstream for more study. "I don't know what a lot of this means yet," he said.
