For over 50 years, the chemical industry kept a dangerous secret: that a group of chemicals known as PFAS—used in products like nonstick pans, waterproof clothing, and food packaging—were harming people and the planet. These toxic substances are now found almost everywhere, and a new study shows just how much companies like DuPont and 3M knew—and covered up.
A team of researchers from UC San Francisco dug into previously hidden internal documents from these chemical giants. Their findings, published in Annals of Global Health, reveal a pattern of deception, similar to the tobacco industry’s tactics to hide the dangers of smoking.
What Are PFAS?
PFAS (per- and polyfluoroalkyl substances) are often called “forever chemicals” because they don’t break down easily. They build up in the environment—and in our bodies—posing long-term health risks, including cancer, liver damage, birth defects, and more.
The Shocking Truth Inside the Documents
The UCSF researchers analyzed industry records dating back to 1961. These documents—uncovered during legal battles and later donated to UCSF’s public Chemical Industry Documents Library—show that chemical companies had plenty of warnings about PFAS toxicity. Yet instead of alerting regulators or the public, they hid the information.
Here are just a few jaw-dropping examples from the documents:
- 1961: DuPont’s own toxicologist warned that Teflon materials caused liver damage in rats and should be handled with “extreme care.”
- 1970s: Internal studies showed PFAS chemicals like C8 were toxic to animals, causing deaths and serious health issues.
- 1980: Two of eight pregnant women working with PFAS gave birth to children with birth defects. DuPont didn’t report these findings or even tell the women.
- 1991: Even as groundwater contamination was being reported near its facilities, DuPont publicly claimed PFAS had “no known toxic effects.”
In one 1980 memo, DuPont went so far as to say that C8 was “about as toxic as table salt.” Behind the scenes, however, the company was destroying internal reports and asking the EPA to publicly defend its products.
A Timeline of Silence and Suppression
The UCSF study lays out a clear timeline: the industry had evidence of PFAS-related health risks at least 21 years before the public learned about them. Researchers found that these companies consistently failed to publish their findings or report them to the Environmental Protection Agency (EPA), despite being legally required to do so under U.S. chemical safety laws.
In 2004, DuPont was fined $16.45 million by the EPA for hiding health data—a record penalty at the time. But that fine was pocket change compared to the $1 billion DuPont earned annually from PFAS products.
Why This Matters Today
According to senior author Dr. Tracey Woodruff, a former EPA scientist, these findings highlight deep flaws in how chemicals are regulated in the U.S. “We’re still playing catch-up,” she says. “These companies were allowed to profit while the public paid the price in health and environmental damage.”
Lead author Dr. Nadia Gaber agrees. “This is a powerful reminder that we need precaution, not reaction, when regulating chemicals. Waiting for definitive proof can cost lives.”
Moving Forward
Many countries are now taking steps to ban or limit PFAS. The UCSF team hopes this research helps guide policy changes, lawsuits, and public awareness. With clear proof of what companies knew and when they knew it, the case for tougher chemical safety laws is stronger than ever.
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