The Minnesota Department of Health says contamination in the drinking water of east metro residents only partly explains the levels of PFCs in their blood.
PFCs leaking from landfills reached water supplies in Oakdale, Lake Elmo, and Cottage Grove. Residents were found to have higher PFC levels in their blood than the general population.
But the Health Department's Michonne Bertrand says within the study group, the water contamination accounts for less than half of the differences in blood levels. Older people had higher levels.
"The longer you've been alive, the more PFCs you've been exposed to, and it kind of builds up in the blood," said Bertrand.
PFCs have been used in consumer products such as food wrappers and non-stick cookware.
Bertrand says filters are being used to remove PFCs from drinking water, and PFCs are being used less and less in consumer products.