Images of starving polar bears staggering across the snow earned the species the dubious honor of being the “poster child” of climate change. But now another human-caused environmental danger threatens these apex predators: pollution from a class of 12,000 chemicals known as per- and polyfluoroalkyl substances (PFAS). And they’re not the only ones.
The nonprofit Environmental Working Group analyzed hundreds of recent peer-reviewed scientific studies and found more than 120 different PFAS compounds in wildlife. Some 330 species were affected, spanning nearly every continent — and that’s just some of what scientists have identified so far.
PFAS have been around since the 1940s in paint, cleaning products, food packaging, nonstick pans, stain-resistant fabric, waterproof clothing, and firefighting foam used at military bases and airports. Dubbed “forever chemicals” because they don’t break down in the environment, they migrate into the soil, water and air — and then into the food chain.
In people different PFAS chemicals have been linked to a range of risk factors, including increased cholesterol, increased risk of pre-eclampsia in pregnant women, decreased vaccine response in children, and increased risk of kidney or testicular cancer.
“The scientific literature shows that PFAS exposure is one of those risk factors that make our western lifestyle unhealthy,” says Catharina Vendl, a wildlife health researcher at the University of New South Wales, Sydney, who is mapping the health risk of PFAS in wildlife. “And unfortunately, wildlife has become unwillingly part of our western lifestyle.”
On the research trail
We have some idea of the human impacts of PFAS pollution, but we still have a long way to go in understanding what it does to wildlife.
The first study published about PFAS in wildlife was in 2001, “which is shocking,” says Vendl, “because the chemicals have been around for ages.” For the next 15 or 20 years, she says, the research was mostly focused on measuring concentrations of PFAS compounds in the bodies of wild animals.
Wherever researchers looked for PFAS, seemingly, they found it, as a map of studies from Environmental Working Group revealed. In recent years they’ve also started working to determine how these chemicals actually affect wild animals’ health — a much more daunting task.
What they’ve learned so far is that there’s evidence that PFAS can pose a threat to immune function, hormone balance and fertility.
For example, studies have found that higher levels of PFAS correlates to higher incidence of disease in sea otters, increased susceptibility to disease in dolphins, reduced foraging behavior in crayfish, and lower hatching success in sea turtles.
A study of American alligators — who can live for 60 years — in North Carolina’s Cape Fear River found that exposure to PFAS “broadly alters immune activities resulting in autoimmune-like pathology.” This included atypical skin lesions and wounds that were slow to heal.
The researchers concluded that the data “reaffirms the need to reduce exposure and cease production and use of a chemical class that, through its ubiquity and persistence, is a global environmental health concern.”
Although the problem is global, one clear pattern emerges: Wild animals who live near areas with larger human populations tend to have higher levels of PFAS in their bodies.
“If we reduce those known sources where there are releases, that can be a step to reducing accumulation in animals and people,” says Tasha Stoiber, a senior scientist at Environmental Working Group who’s involved in its mapping project. “Because those higher levels do track with more developed and populated areas.”
Polar bears and the Arctic
Unfortunately the high mobility and longevity of PFAS also means that even the most remote wildlife face risks, too. Research in the early 2000s found high concentrations of PFAS in Arctic ocean waters and animals.
“That was a wake-up call to the research community, because if PFAS was being found in remote wildlife in the Arctic, then it was surely everywhere,” says Vendl. It also inspired increased research efforts on environmental toxicity from scientists in Norway.
“What those researchers found was that polar bears have the highest level of PFAS of all wildlife species in the Arctic, comparable to concentrations of people who work in or live near a PFAS manufacturing plant in China,” she says.
Their study concluded that, “PFAS exposure in Arctic biota, in particularly in polar bears, is alarming.”
What does that mean for the bears’ health?
“The toxicologist who works on those polar bears told me that it’s really hard to say because they only see the animals once, and if they’re in bad body condition, it could be the result of climate change and not finding enough food,” says Vendl. But modeling studies suggest “that it goes towards reduced fertility and messed up hormonal balances,” because some PFAS components have an effect that’s similar to the effect of estrogen in mammalian bodies.
There’s still much to be learned about how wild animals are affected, but Vendl’s work has found that there are already big geographic gaps in where research is occurring.
Studies have been heavily focused in wealthier countries, including in North America, Europe and China, which spend more on scientific research generally. But PFAS abounds globally, and many less affluent countries, including those in the Global South, have the same contamination issues.
“Those countries will have as much — or more — exposure to PFAS,” she says. “But there’s barely any research measuring concentrations because there’s no money and therefore little interest. And that’s a big issue.”
Another looming problem with PFAS is how to regulate this broad class of chemicals.
Two of the more commonly used compounds, PFOS and PFOA, have been phased out in North America and Europe, but production continues in Asia. In the United States, the Environmental Protection Agency launched a strategic roadmap for addressing PFAS pollution in 2021 and has just announced a proposed drinking-water standard for six of those chemicals.
It’s a necessary and overdue step, but it only scratches the surface of a much greater problem.
With new regulations exposing health risks of long-time PFAS compounds, manufacturers are producing a new generation of the chemicals. But there’s an inevitable lag in studying the impacts and assessing any potential harm.
“So for a few years companies can do whatever they want,” says Vendl, “By the time we realize it’s a problem, they move on to another chemical and it starts all over again.”
That’s why it’s important to regulate the entire class of fluorinated chemicals, which have similar structures and properties, says Stoiber.
“The more that we study PFAS and the more that we study the replacements, the more that we’re seeing that they act the same and many of them have the same health impacts,” she says. “We need to make sure that when we’re tackling this, we’re looking at the whole class of chemicals so that we don’t have these regrettable substitutions that are going to be just as much of a problem as the original chemicals.”
And the time to do that is now, she says. Many wildlife species are facing unprecedented rates of decline from climate change and habitat loss and degradation. Chemical pollution adds another pressure — and one that could prove too much.
“Those effects might not be as visible, but the harms that animals might sustain as a result of these chemicals may leave them less likely to deal with some of some of these other factors,” she says. “All of these pressures acting together simultaneously on animals is a huge problem that we need to tackle.”
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