News reports implying a new threat from chemicals made by the 3M Co. are misleading, according to officials of the Minnesota Department of Health and 3M.
A headline on a Thursday article in the Minneapolis-based Star Tribune said “Study: Death rate up for 3M workers exposed to PFOA.”
“I just about fell off my chair when I saw that,” Health Department spokesman Doug Schultz said.
That story was followed by reports on Minnesota Public Radio and in newspapers across the state.
The stories reported one finding of a study of 4,000 3M workers — that workers with high exposure to PFOA, or perfluorooctanoic acid, had higher rates of deaths from prostate cancer and strokes than other workers.
But the “high” death rates in the study are slightly below normal when compared with the entire population — and appear high only because the death rate among the other workers was abnormally low.
The study said that of 371 deaths of workers not exposed to PFOA, four were caused by prostate cancer — compared with the 11 that would have been expected in the general population.
The study, which was completed in August, was another in many studies of workers at a 3M manufacturing plant in Cottage Grove, according to Bill Nelson, a 3M spokesman. The Maplewood-based company has been tracking the health of workers exposed to PFOA since the 1980s.
3M’s manufacture of PFCs — or perfluorochemicals, including PFOA — began in the 1940s for use in products such as Teflon and Scotchgard stain repellent. The PFCs are resilient; traces of the chemicals have been found in animals around the world.
The stories Thursday and Friday did not report another finding of the most recent study — that PFOA was linked with lower rates of heart disease.
Nelson said that finding illustrates the difficulty of interpreting studies. Studies such as these point out associations, but do not prove one factor causes another.
“When you compare conditions in a group, you can find associations,” said John Stine, another spokesman for the Health Department.
Some of the stories implied that PFOA caused the deaths, Nelson said.
“Not only is that in error, but that is not the point of the study to begin with,” Nelson said. “It’s a statistical anomaly.”
Stine said officials discussed the study findings in August. Nothing in the study, he said, persuaded them to change the recommended safe level of chemicals found in minute traces in drinking water in Washington County.
Officials said the death rate — from prostate cancer or any other known cause — of workers at the plant was comparable to the rate in the general population. This is true even though many workers had absorbed up to 100 times the amount of PFOA found in the general public, said Nelson.
Nelson said no one has shown that PFCs are harmful to humans.
Since the 1940s, more than 1,500 studies have shown that while megadoses produce various ailments in animals, there is no study showing any harmful effects on humans from any level of exposure to PFCs.
