‘Forever chemicals’ could age dolphins beyond their years

Exposure to trace metals and “permanent chemicals” could cause dolphins to age prematurely, raising concerns about marine pollution and impacts on human health.

Metals such as zinc and copper can end up in the ocean from industrial and mining waste. The same goes for per- and polyfluoroalkyl substances, or PFAS, which are often called forever chemicals because of how long they persist in the environment.

Scientists have already documented the harmful effects of metals and PFAS in wildlifeincluding dolphins. A 2013 study found that bottlenose dolphins heavily exposed to PFAS showed signs that the compounds were disrupting their activity. their liver, kidneys and immune system. And earlier this year, researchers showed that mother dolphins could transfer PFAS compounds to their offspring through milk, thus contributing to early exposure in life.

Now it seems that dolphins are common (Delphinus Delphinus) exposed to these toxic substances are aging faster than they should bereport the researchers on June 26 in an article published on bioRxiv.org. The work has not yet been peer-reviewed.

Dolphins are often used as proxies for human health because they live just as long, breathe the same air, and eat the same seafood as we do. How these animals respond to toxin accumulation can help predict harmful effects in humans. The new study is the first to explore the association between these substances and accelerated aging in a marine mammal.

There are two ways to talk about aging, says Karen Stockin, a marine biologist at Massey University in Auckland, New Zealand. Chronological age is your age in calendar years. Biological age is based on the state of your DNA, which naturally degrades over time at specific rates depending on species.

This process can be accelerated by external factors such as stress or pollution. Accelerated biological age can lead to the early onset of cancer or chronic diseases, conditions generally associated with old age.

Stockin and his colleagues collected liver and kidney samples from 75 dolphins that died in unrelated incidents between 2000 and 2023. The team compared the concentrations of trace metals and PFAS substances with the biological and chronological ages of the dolphins.

Stockin expected that the total amount of these toxins would help accelerate aging. Instead, only certain subsets of metals and PFAS substances explained the difference between biological and chronological age.

“It’s not the total PFAS burden that you have,” Stockin says. “It is which You have PFAS compounds.

Although often grouped together, PFAS includes tens of thousands of diverse chemicals. PFBA, a chemical used in nonstick pans and firefighting foams, was the main compound associated with accelerated aging in dolphins. Another associated compound, PFNA has been linked to accelerated aging in humansAlso.

For metals, the worst offender was seleniuma trace element essential to several physiological processes that can become toxic at higher doses. Other elements causing the relationship with accelerated aging include zinc, copper, aluminum and manganese.

Together, this subset of metals and PFAS substances explains more than half of the accelerated aging observed in dolphins, the team found.

The study results reinforce concerns that contaminants can cause damage outside of the tissues where they accumulate, says ecotoxicologist Baylin Bennett of the University of California, San Francisco, who was not involved in the research.

Understanding how multiple pollutants work in tandem to affect the health of dolphins and humans is the next step.

Dolphins, like humans, accumulate toxins over time and are rarely exposed in isolation. “It’s not like it’s just metals or PFAS or plastics or phthalates,” Stockin says. “It’s a mix of all those things.”