Tissue of some fish taken from the Mississippi River near 3M Co.’s Cottage Grove plant contains high levels of two controversial industrial chemicals that were once made at the plant and dumped into the river, 3M’s own research says.
The laboratory findings of 62 fish collected from three sections of the river in August show a wide range of perfluorochemical levels. But they generally show lower PFC concentrations upstream of the plant and higher ones near the plant or downriver.
The findings represent the broadest look so far into PFC levels in whole bodies or fillets, which wildlife and people are most likely to consume. Earlier lab samples showing high levels of PFCs focused mainly on liver and blood.
3M had the work done at a Pennsylvania laboratory as part of a larger effort to determine the extent of PFC contamination in the east metro. PFCs, a family of chemicals that do not break down in the environment, were once made at the plant and used in products that resist heat, oil, water and grease.
High PFC levels have been tied to liver and developmental problems in laboratory animals, but 3M contends its research hasn’t shown health problems in people.
A spokesman for the Minnesota Pollution Control Agency, which has sent a similar sampling of fish to a different laboratory, said Friday that it plans to study the data and determine what should be done next.
3M, meanwhile, cautioned against reading too much into the data.
“What we can conclude is more work needs to be done,” spokesman Bill Nelson said.
Many of the fish analyzed had negligible amounts of perfluoroocotanic acid, or PFOA, and perfluorooctane sulfate, or PFOS. Both are in the PFC family.
Concentrations of chemicals varied by location, according to the findings.
In a stretch just upriver from the plant, PFOS concentrations in a smallmouth bass were as high as 178 parts per billion; in a stretch adjacent to the plant, a smallmouth had 1,320 ppb of PFOS and a bluegill was determined to have a level of 9,000 ppb.
Immediately downriver from the plant, a smallmouth had 5,150 ppb of PFOS.