Whistleblower Details Company’s 1970s Knowledge of “Forever Chemical” Health Risks
A former 3M scientist revealed that the company had discovered widespread PFAS contamination in human blood samples as early as 1975, decades before alerting regulators or the public. Kris Hansen, who worked at 3M from 1996 to 2022, uncovered the presence of PFOS—a type of PFAS chemical—in blood samples across multiple countries during her 1997 research. Internal company documents show that 3M’s own testing in 1976 resulted in the death of seven out of ten laboratory rats within two weeks of PFAS exposure. Hansen’s whistleblower account, first shared with ProPublica, details how 3M executives dismissed or downplayed these findings for years while continuing to manufacture these chemicals.
5 Key Points
- 3M’s 1976 laboratory tests killed seven out of ten rats within two weeks of PFAS exposure.
- Blood samples from Korean War recruits in the 1950s tested negative for PFAS, predating 3M’s chemical production.
- A 1979 consultant warned 3M executives about “serious problems” if the chemicals proved widespread.
- Hansen discovered PFOS contamination in blood samples from multiple countries in 1997.
- 3M plans to cease PFAS manufacturing by the end of 2025.
The Discovery that Changed Everything
In 1997, at age 28, Kris Hansen followed her father’s footsteps into 3M’s environmental lab, where a routine assignment would uncover one of the largest environmental contamination cases in U.S. history. Her boss tasked her with identifying an unknown compound in random human blood samples. Using advanced analytical techniques, Hansen identified the substance as PFOS, a fluorochemical manufactured exclusively by 3M. “I figured out that the interferent was PFOS, which is a fluorochemical compound manufactured, at the time, exclusively by 3M,” Hansen said. She expanded her testing to blood samples from multiple countries to verify her findings. Each sample revealed the same distinct chemical signature unique to 3M’s patented process. “The process that 3M uses is very distinct and patented,” Hansen explained, describing how the discovery shook her confidence in the company. When she brought these findings to her supervisor, his response suggested the magnitude of her discovery: “He looked at it, and he said, ‘This changes everything,’ and he walked into his office. It’s a very distinct memory for me.”
Decades of Hidden Knowledge
Hansen’s investigation revealed a pattern of corporate concealment dating back to the 1970s. In 1998, during a conversation with another 3M scientist, she learned the company had known about PFAS contamination for decades. “I don’t understand why they’re making such a big deal. We knew about this in 1975,” the scientist told her. To establish a historical baseline, Hansen tested preserved blood samples from Korean War recruits from the 1950s—a period before 3M began commercial production of fluorochemicals. These samples tested negative, providing irrefutable evidence of when contamination began. Documents released in 3M’s 2018 settlement with Minnesota painted an even more troubling picture. A 1976 laboratory test exposed ten rats to PFAS—seven died within two weeks. In 1979, a consultant warned 3M executives in stark terms about fluorochemicals: “If the levels are high and widespread and the half-life is long, we could have a serious problem.” Despite these early warnings, 3M continued manufacturing PFAS while keeping their findings from the public.
A Pattern of Corporate Indifference
Hansen’s attempts to raise awareness within 3M met with mounting resistance. After her initial discovery in 1997, she expected swift action from company leadership. “I really thought that they would be as kind of appalled and surprised and shocked as I was and that they would want to say, ‘How did this happen, and how do we fix it?'” Hansen recalled. Instead, months passed with no meaningful response. In 1999, she secured a meeting with 3M’s CEO to present her findings directly. The response stunned her: “The CEO who was sitting at the head of the table the whole time we were talking actually fell asleep during my presentation,” Hansen said. Following this meeting, she received explicit instructions not to share her data outside the company—the same directive given to scientists who made similar discoveries in the 1970s. “It made me understand that there had been some amount of coverup in the company,” Hansen explained. “It’s one thing to lose track of a chemical. Unforgivable. But it’s another thing to intentionally cover it up.”
The Environmental Legacy
Today, from her home in Afton, Minnesota, Hansen tends to her organic garden while contemplating the far-reaching implications of PFAS contamination. The impact centers on Maplewood, Minnesota, which she describes as “ground zero for one of the biggest environmental contamination stories of our time.” Despite 3M’s recent announcement to exit PFAS manufacturing by 2025, the environmental damage spans decades. The company’s 2018 settlement with Minnesota revealed extensive groundwater contamination, but Hansen believes this represents only a fraction of the total environmental impact. Her perspective carries particular weight given her family’s deep connections to 3M—her father served as the company’s highest-ranked scientist during his 40-year career. “For most of my life, certainly for my career at 3M, I believed 3M’s line that they were not toxic,” Hansen reflected. “I feel guilty, I feel disappointed, I feel angry.” While 3M has begun addressing its PFAS legacy through legal settlements and manufacturing changes, Hansen maintains that the company’s financial obligations for environmental remediation remain far from complete.
A Reckoning for Corporate Responsibility
3M’s response to Hansen’s revelations highlights the growing tension between corporate interests and public health. While the company maintains it has “shared significant information about PFAS” through scientific journals since the 1980s, documents and testimony paint a different picture. 3M announced its exit from PFAS manufacturing by the end of 2025. Still, the chemicals’ persistence in the environment—earning them the nickname “forever chemicals”—ensures their impact will outlast their production. As groundwater contamination continues to affect communities across Minnesota and beyond, Hansen’s whistleblower account provides crucial evidence of how early warnings were ignored. Her story, emerging from the intersection of science, corporate responsibility, and environmental justice, may reshape how companies approach chemical safety and transparency in the future. “I have a ton of faith in scientists and engineers at 3M and in other places,” Hansen said, emphasizing that her former employer’s obligations to address contamination remain far from complete. The full scope of PFAS contamination, its health implications, and the cost of cleanup continue to unfold, with Hansen’s testimony adding a crucial piece to this unfolding environmental story.
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