UW–Madison Smart Restart: For information about fall semester instruction and campus operations, please visit For COVID-19 news updates, see

During this time, please contact us at

If every writer has a muse, then Nancy Langston’s is surely Lake Superior. An environmental historian who has written three books about people’s connection to natural places, Langston fell in love with the lake’s shimmering blue expanse while house-sitting for a colleague several summers ago. Within a month she’d begun looking for her own lakeside retreat, and soon found it in a 10- by 20-foot shed, to which she and her husband added insulation and a floor. Here she has spent every summer since, drawing inspiration from the rare beauty of her surroundings: the vast, unbroken forests, the beaches of polished stones, the serenity of her kayak slicing through the waves. And, of course, the fish—succulent, fresh-caught lake trout so alive with flavor they could be a muse all on their own. Her days often ended with a trip to the market for a few fresh fillets to cook for dinner.

But Langston doesn’t eat lake trout nearly as often anymore. Despite its divine flavor and undeniable health benefits—including a wallop of omega-3 fatty acids—she fears that her habit of eating trout three or four times a week was doing harm to her body. One concern is toxaphene, a pesticide sprayed extensively on cotton fields in the 1960s and ’70s that has found its way into Lake Superior waters. A member of the infamous “dirty dozen” organic chemicals outlawed in 2004 by the international Stockholm Convention—along with PCBs, DDT and dioxins—toxaphene has been linked to kidney and liver problems and increased risk of cancer. Still more troubling is how toxaphene levels have risen over time in large, predatory Lake Superior fish such as lake trout, even as traces of other banned chemicals have declined.

Langston, a professor with UW’s Nelson Institute for Environmental Studies and CALS’ Department of Forest and Wildlife Ecology, had never heard of toxaphene before reading chemist Melvin Visser’s 2007 book Cold, Clear and Deadly, which chronicled the history of the pollutant in the Great Lakes. Visser’s tale put an abrupt end to her love affair with lake trout.

“Now I know enough that I mostly eat whitefish,” she says. “It’s lower on the food chain so it’s less high in contaminants. But it’s also less abundant in healthy fats. And it just doesn’t taste as good.”

In her dilemma over fish, Langston is hardly alone. Consumers are told repeatedly that fish is among the healthiest sources of protein in our diets. Eating fish twice a week can help stave off heart attacks and lower cholesterol. Doctors encourage women to eat more fish during pregnancy to prevent early delivery and foster fetal brain development. But looming over these benefits is a dark warning about toxic chemicals with the potential to cause cancer, neurological problems and reproductive dysfunction. Worse still, the dangers are rarely clear, varying greatly among fish species and location, making it tough for consumers to know how to protect themselves.

“It’s a real quandary for anybody: Can you eat the fish? Is it healthy to eat fish?” says Marty Kanarek, an environmental epidemiologist in the UW-Madison School of Medicine and Public Health who has studied contaminants in fish and their impacts on people. “You know, when you go to the grocery store, the price per unit (on foods) is marked carefully, the calories are labeled, all kinds of ingredients are labeled. But the labels don’t tell you which fish is safe and which isn’t.”

How did we reach this place, where one of our healthiest foods has grown so complicated? As is true of many contemporary questions, the answers lie in the past, Langston says. In her latest book, Toxic Bodies, she delves into a 70-year history of industrialization and environmental pollution that begins to explain why we’re facing a problem with fish. But the story is much more than that. Mostly, it’s about us—us and the unbreakable tie to the world around us, a connection that is at once obvious and easy to forget.

It was not a fish, but an endangered bird, that first drew Langston’s attention to the influence of humans in ecosystems. As a graduate student pursuing her Ph.D. in ecology, she traveled to Zimbabwe to observe bird populations in a national park, but she quickly found herself more interested in an unfolding human story. A flood of refugees from neighboring Zambia had stirred fears about poaching, leading park officials to warn that any African caught inside the park would be shot on sight. At the same time, Zimbabwe’s own agricultural lands were shifting heavily toward commodity crops such as sugarcane, creating pressure to open parklands to settlement and farming. Langston soon became convinced that the real driving factor in environmental change was human culture. Understanding and reversing environmental decline, she realized, required watching more than birds. It meant observing people.