Hansen was deeply troubled by what she read. One paper, published in 2012 in the Journal of the American Medical Association, found that, in children, as PFOS levels rose so did the chance that vaccines were ineffective. Children with high levels of PFOS and other fluorochemicals were more likely to experience fevers, according to a 2016 study. Other research linked the chemicals to increased rates of infectious diseases, food allergies, and asthma in children. Dozens of scientific papers had found that, in adults, even very low levels of PFOS could interfere with hormones, fertility, liver and thyroid function, cholesterol levels, and fetal development. Even PFBS, the chemical that 3M chose as a replacement for PFOS, caused developmental and reproductive irregularities in animals, according to the Minnesota Department of Health.
Reading these studies, Hansen felt a paradoxical kind of relief: as bad as PFOS seemed to be, at least independent scientists were studying it. But she also felt enraged at the company, and at herself. For years, she had repeated the company’s claim that PFOS was not harmful. “I’m not proud of that,” she told me. She felt “dirty” for ever collecting a 3M paycheck. When she read the documents released by the Minnesota A.G., she was horrified by how much the company had known, and how little it had told her. She found records of studies that she had conducted, as well as the typed notes from her meeting with Newmark.
“Fine, Jess, you’ve got the longest bolo tie.”
Cartoon by José Arroyo
In October, 2022, after Hansen had been at 3M for twenty-six years, her job was eliminated, and she chose not to apply for a new one. Three months later, she wrote me an e-mail, offering to speak about what she had witnessed inside the company. “If you’d be interested in talking further, please let me know,” she wrote. The next day, we had the first of dozens of conversations.
When Hansen first told me about her experiences, I felt conflicted. Her work seemed to have helped force 3M to stop making a number of toxic chemicals, but I kept thinking about the twenty years in which she had kept quiet. During my first visit to Hansen’s home, in February, 2023, we sat in her kitchen, eating bread that her husband had just baked. She showed me pictures of her father and shared a color-coded time line of 3M’s history with forever chemicals. On a bitterly cold walk in a local park, we tried to figure out if any of her colleagues, besides Newmark, had known that PFOS was in everyone’s blood. She often sprinkled her stories with such Midwesternisms as “holy buckets!”
During my second trip, this past August, I asked her why, as a scientist who was trained to ask questions, she hadn’t been more skeptical of claims that PFOS was harmless. In the awkward silence that followed, I looked out the window at some hummingbirds.
Hansen’s superiors had given her the same explanation that they gave journalists, she finally said—that factory workers were fine, so people with lower levels would be, too. Her specialty was the detection of chemicals, not their harms. “You’ve got literally the medical director of 3M saying, ‘We studied this, there are no effects,’ ” she told me. “I wasn’t about to challenge that.” Her income had helped to support a family of five. Perhaps, I wondered aloud, she hadn’t really wanted to know whether her company was poisoning the public.
To my surprise, Hansen readily agreed. “It almost would have been too much to bear at the time,” she told me. 3M had successfully compartmentalized its secret; Hansen had only seen one slice. (When I sent the company detailed questions about Hansen’s account, a spokesperson responded without answering most of them or mentioning Hansen by name.)
Recently, I thought back on Taves and Guy, the academic scientists who, in the seventies, came so close to proving that 3M’s chemicals were accumulating in humans. Taves is ninety-seven, but when I called him he told me that he still remembers clearly when company representatives visited his lab at the University of Rochester. “They wanted to know everything about what we were doing,” he told me. But the exchange was not reciprocal. “I soon found out that they weren’t going to tell me anything.” 3M never confirmed to Taves or Guy, who was a postdoctoral student at the time, that its fluorochemicals were in human blood. “I’m sort of kicking myself for not having followed up on this more, but I didn’t have any research money,” Guy told me. He eventually became a dentist to support his wife and family. (He died this year, at eighty-one.) Taves, too, left the field, to become a psychiatrist, and the trail ended there.
Last year, while reading about the thousands of PFAS-related lawsuits that 3M was facing, I was intrigued to learn that one of them, filed by cities and towns with polluted water, had produced a new set of internal 3M documents. When I requested several from the plaintiff’s legal team, I saw two names that I recognized. In a document from 1991, a 3M scientist talked about using a mass spectrometer—the same tool that Hansen would use years later—to devise a technique for measuring PFOS in biological fluid. The author was Jim Johnson—and he had sent the report to his boss, Dale Bacon.
This revelation made me gasp. Johnson had been Hansen’s first boss and had instigated her research into PFOS. Bacon had questioned her findings and ultimately told her to stop her work. (In a sworn deposition, Bacon said that by the eighties he had heard, during a water-cooler chat with a colleague, that Taves and Guy had found PFOS in human blood.) What I couldn’t understand was why Johnson would ask Hansen to investigate something that he had already studied himself—and then act surprised by the results.
Jim Johnson, who is now an eighty-one-year-old widower, lives with several dogs in a pale-yellow house in North Dakota. When I first called him, he said that he had begun researching PFOS in the seventies. “I did a lot of the very original work on it,” he told me. He said that when he saw the chemical’s structure he understood “within twenty minutes” that it would not break down in nature. Shortly thereafter, one of his experiments revealed that PFOS was binding to proteins in the body, causing the chemical to accumulate over time. He told me that he also looked for PFOS in an informal test of blood from the general population, around the late seventies, and was not surprised when he found it there.
Johnson initially cited “four hundred and eighty pounds of dog” as a reason that I shouldn’t visit him, but he later relented. When I arrived, on a chilly day in November, we spent a few minutes standing outside his house, watching Snozzle, Sadie, and Junkyard press their slobbery snouts against his living-room window. Then we decamped to the nearest IHOP. Johnson, who was dressed in jeans and a flannel shirt, was so tall that he couldn’t comfortably fit into a booth. We sat at a table and ordered two bottomless coffees.
In an experiment in the early eighties, Johnson fed a component of Scotchban to rats and found that PFOS accumulated in their livers, a result that suggested how the chemical would behave in humans. When I asked why that mattered to the company, he took a sip of coffee and said, “It meant they were screwed.”
At the time, Johnson said, he didn’t think PFOS caused significant health problems. Still, he told me, “it was obviously bad,” because man-made compounds from household products didn’t belong in the human body. He said that he argued against using fluorochemicals in toothpaste and diapers. Contractors working for 3M had shaved rabbits, he said, and smeared them with the company’s fluorochemicals to see if PFOS showed up in their bodies. “They’d send me the livers and, yup, there it was,” he told me. “I killed a lot of rabbits.” But he considered his efforts largely futile. “These idiots were already putting it in food packaging,” he said.
Johnson told me, with seeming pride, that one reason he didn’t do more was that he was a “loyal soldier,” committed to protecting 3M from liability. Some of his assignments had come directly from company lawyers, he added, and he couldn’t discuss them with me. “I didn’t even report it to my boss, or anybody,” he said. “There are some things you take to your grave.” At one point, he also told me that, if he were asked to testify in a PFOS-related lawsuit, he would probably be of little help. “I’m an old man, and so I think they would find that I got extremely forgetful all of a sudden,” he said, and chuckled.
Out the windows of IHOP, I watched a light dusting of snow fall on the parking lot. In Johnson’s telling, a tacit rule prevailed at 3M: not all questions needed to be asked, or answered. His realization that PFOS was in the general public’s blood “wasn’t something anyone cared to hear,” he said. He wasn’t, for instance, putting his research on posters and expecting a warm reception. Over the years, he tried to convince several executives to stop making PFOS altogether, he told me, but they had good reason not to. “These people were selling fluorochemicals,” he said. He retired as the second-highest-ranked scientist in his division, but he claimed that important business decisions were out of his control. “It wasn’t for me to jump up and start saying, ‘This is bullshit!’ ” he said, and he was “not really too interested in getting my butt fired.” And so his portion of 3M’s secret stayed in a compartment, both known and not known.
Johnson said that he eventually tired of arguing with the few colleagues with whom he could speak openly about PFOS. “It was time,” he said. So he hired an outside lab to look for the chemical in the blood of 3M workers, knowing that it would also test blood-bank samples, for comparison—the first domino in a chain that would ultimately take the compound off the market. Oddly, he compared the head of the lab to a vending machine. “He gave me what I paid for,” Johnson said. “I knew what would happen.” Then Johnson tasked Hansen with something that he had long avoided: going beyond his initial experiments and meticulously documenting the chemical’s ubiquity. While Hansen took the heat, he took early retirement.
