A major producer of PFAS in the United States, 3M, dismisses these findings. “PFAS is a broad category, including thousands of substances with diverse physical and chemical properties, uses, and characteristics,” said Sean Lynch, a 3M spokesperson. “While the science behind PFAS is complex, the weight of scientific evidence does not show that PFOS or PFOA, two types of PFAS, cause harm in people at current or past levels.”
Epidemiologists generally can’t pinpoint the cause of a person’s gestational diabetes or obesity, said Philippe Grandjean, M.D., Ph.D., an environmental epidemiologist at the Harvard T.H. Chan School of Public Health. But on average, they can see that PFAS increases the risk of health problems such as metabolic disease and immune deficiency.
Manufacturers treat products from raincoats to pizza boxes with PFAS because they repel water, heat and grease, thanks to the unique properties of their superstrong fluorine-carbon bonds. These bonds make PFAS so resistant to degradation they’re called “forever chemicals” by some scientists.
And their widespread use has left nearly everyone exposed. As the chemicals linger, they concentrate in blood, breast milk and numerous tissues. Scientists are particularly concerned pregnant mothers might pass on the chemicals through the placenta, which manages the baby’s metabolic needs while guarding against infection.
Anecdotal reports from over a century ago showed that toxic substances like morphine and lead cross the placenta but it was long assumed that most chemicals did not. In 1981 DuPont scientists analyzed the umbilical cord blood of workers’ newborns and found that PFAS crossed the placenta, but they did not publish the finding.
Federal law requires companies to inform the Environmental Protection Agency immediately if they learn a chemical poses risks to human health or the environment. The EPA filed a complaint against DuPont in 2004 for failing to report its finding, after receiving internal documents obtained through a separate lawsuit.
“Scientific evidence confirms that the trace amount of PFOA found in this one data point would pose no risk to human health,” a lawyer for the company responded. “In the absence of substantial risk of harm, the information is simply not required to be reported.”