For years, Kris Hansen worked as a scientist at 3M, the conglomerate her father dedicated his 40-year career to. But it wasn't until she stumbled upon a troubling discovery in 1997 that Hansen's faith in the company began to unravel.

At the time, Hansen was tasked with identifying an unknown substance present in random human blood samples. Her research led her to a startling conclusion: the samples contained PFOS, a fluorochemical compound manufactured exclusively by 3M. Further testing revealed PFOS was not only widespread in the American population but also present in samples from around the world.

Hansen immediately brought her findings to her supervisor, expecting the company to be as alarmed as she was. Instead, she was met with what she describes as inaction.

It wasn't until a 1998 meeting that Hansen learned she wasn't the first to uncover PFAS contamination. A colleague casually mentioned the company had known about the issue since the 1970s. This revelation, along with documents later released showing 3M's awareness of PFAS toxicity dating back to animal tests in the 1970s, led Hansen to believe the company had engaged in a decades-long cover-up.

Despite her growing unease, Hansen remained with 3M until 2022. Now, she speaks out against her former employer, alleging they knowingly put profits over public safety.

3M responded to Hansen's allegations with a statement highlighting their commitment to phasing out PFAS manufacturing and their history of publishing research on the chemicals. However, critics argue the company's actions have come too slowly and only in response to mounting legal and public pressure.

The impact of 3M's actions is evident in communities like Maplewood, Minnesota, where PFAS contamination has had devastating environmental consequences. As states begin to implement stricter regulations on "forever chemicals," the financial and moral obligations facing 3M and other responsible companies will only continue to grow.

Hansen has since come forward to share her story with the New Yorker, ProPublica and CBS News. In the New Yorker / ProPublica story, Elsie Sunderland, an environmental chemist at Harvard University, shared her perspective on the magnitude of the contamination problem.

"When you have a contaminated site, you can clean it up," she concluded. "When you ubiquitously introduce a toxicant at a global scale, so that it's detectable in everyone, we're reducing public health on an incredibly large scale."