What Loons Can Tell Us About PFAS

The following story by Kate Olson is a case study from the National Wildlife Federation that includes the work of Sandwich resident Tiffany Grade, the wildlife biologist with the Loon Preservation Committee. Please consider donating to both organizations, using the links at the end of the story. 

Among the most enduring sounds of summer in North America’s northern forest is the singular call of the common loon. Plaintive yet serene, it conjures images of quiet lakes, glowing sunsets and the iconic black and white birds.

Despite the loon’s emblematic status, however, populations have been fluctuating for decades. Extensive research has documented some of the human activities likely responsible, from the use of lead-based fishing tackle to lakeshore development, climate change and pesticides. In New Hampshire, scientists are investigating whether there may be another culprit: PFAS.

PFAS, or per- and polyfluoroalkyl substances, are a class of at least 15,000 synthetic compounds valued for their incredible durability. Among the most widely used and studied is perfluorooctanoic acid, or PFOA, essential to nuclear weapons production during World War II and famously used to make Teflon.

Over time, manufacturers found uses for PFAS in almost everything: food packaging, clothing, furniture, cosmetics and more. A number of PFAS compounds, commonly referred to as “forever chemicals,” are now banned from production in the United States. But given their ability to resist degradation, they remain in our environment—and us—indefinitely.

PFAS’ known effects on human health range from increased immunosuppression and reduced vaccine efficacy to reproductive problems and higher likelihood of some cancers and other diseases.

The chemical industry has long been aware of the dangers, in part due to animal studies conducted in the 1970s and ’80s but only made public through legal action against 3M and DuPont decades later. Concern has grown in recent years, with increased public awareness of PFAS’ presence in drinking water, food and even on organic farms.

PFAS were found in 95 percent of human blood samples tested for a U.S. study published in 2011, in Arctic ice cores and, increasingly, in wildlife. According to the Environmental Working Group (EWG), at least 600 wildlife species around the world are impacted by PFAS, and that number could grow as EWG catalogs additional completed studies.

Scientists have documented health effects in animals similar to those in humans, with lab studies showing elevated levels of PFAS reducing disease immunity in dolphins, alligators and sea otters. In seabirds, early research finds that PFAS interrupt liver function.

Tiffany Grade knows well the connection people have with loons. Grade is the wildlife biologist for the Loon Preservation Committee in New Hampshire, home to the most comprehensive loon productivity and mortality database in the world. “One of my earliest memories is of my parents pointing out loons to me on the lake in northern Wisconsin,” she says.

In the mid-2000s, one of New Hampshire’s premier loon habitats—Squam Lake, made famous by the movie “On Golden Pond”—experienced unprecedented declines, including a 44 percent decrease in paired loon adults in 2005 alone. The drop led to expanded contaminant testing in lakes across the state. Grade has been sampling inviable eggs, or those that fail to hatch, for environmental contaminants, including PFAS, since 2007.

Loons are long-lived, with life spans up to 30 years. They are also at the top of the aquatic food web, which means their bodies accumulate contaminants from further down the chain. As territorial birds, loons tend to pick a spot on a lake and protect it fiercely for four to six weeks before laying eggs.

Because they stay and feed intensively in the same location, loons are “an amazing snapshot of what the [contaminant] levels are in that territory at that moment,” Grade says, adding that bird eggs are increasingly used as biomonitoring tools.

So far, all tested eggs from New Hampshire reveal perfluorooctane sulfonic acid (PFOS), in addition to other chemicals such as the banned insecticide known as DDT. PFOS—a water repellent used in stain-resistant fabrics and firefighting foam—was phased out of U.S. manufacturing in the early 2000s. In keeping, loon eggs reveal declining levels of PFOS through 2021, but other PFAS compounds—such as PFCAs, or perfluoroalkyl carboxylic acids, often used in industrial processes—are increasing.

“What’s really concerning about that is people do not really know what the impact of PFCAs are on wildlife,” Grade says. “It’s fantastic that PFOS is on the decline, but what about these other types of PFAS?”

This mirrors a broader PFAS conundrum. Each compound is slightly different, and regulations thus far have focused on banning a single chemical at a time, leaving thousands of others in environmental circulation while allowing the chemical industry to find new and potentially dangerous substitutes.

Scientists increasingly recommend following the lead of the European Union, where policy guidelines call for phasing out the entire class of chemicals by 2030, a recommendation members of the chemical industry have resisted.

Environmentalists say more research is needed to understand how PFAS affect loon mortality and reproduction, and the Loon Preservation Committee is partnering with the state of New Hampshire to conduct the largest scientific study of these types of contaminants in loon eggs.

The outcomes of the study, available later this year, will have implications beyond loons. Grade says the data will shed light on the extent of ecosystem exposure to PFAS and other contaminants—information that in turn will help evaluate current PFAS mitigation policies.

“There is so little we know about PFAS,” Grade says. “Because loons are such an amazing indicator species, this will really help us understand the impacts of PFAS on loons, other wildlife and people in New Hampshire.”

Writer and sociologist Kate Olson, Ph.D., lives in the Wabanaki homeland in what is also called Maine.

Please consider donating  to the Loon Preservation Committee and the National Wildlife Federation.


  1. Steve Foley 5 months ago February 28, 2024

    Europe over the years has prohibited many chemicals from food and products which our “FDA” has allowed regardless European concerns.
    I’d say if there’s one thing we can take from this it’s we need to consider Europe’s policies regarding all chemicals.
    Great Loon article. It’s time we ask why, in the last 50 years do we need all these chemicals as we’ve come so far for thousands of years without. Follow the $$$$

  2. Mike Lane 5 months ago February 28, 2024

    I remember the only man-made loon nest anchored in the cove in Berry Bay, when I was a child in the 1970s. We’ve come a long way. Loons and Bald Eagles were a scarcity back then. But we must be vigilant.

  3. Patricia Riker 5 months ago February 28, 2024

    All the more reason Ossipee Planning Board should deny multiple docks on that private island as the LOONS WILL BE DOOMED if that happens.
    Maybe that couple from Massachusetts could negotiate with the Town of Ossipee a better, more ecological friendly solution for all involved…..


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