PFAS: How birds of prey expose forever chemicals in nature

PFAS, often called “forever chemicals”, are found in frying pans, waterproof jackets and cosmetics – and have now also penetrated deep into the natural world. An Italian research team has shown how birds of prey can help trace this invisible poison more effectively. These animals are becoming living measuring instruments for contamination that has long affected people too.

What lies behind “forever chemicals”

PFAS is the collective term for per- and polyfluorinated chemicals, which are exceptionally stable. That very durability makes them useful – and hazardous.

• They repel water and grease.
• They withstand heat and friction.
• They barely break down in the environment.

PFAS can be found, among other places, in:

• non-stick coatings on frying pans and saucepans
• outdoor and performance clothing
• firefighting foams
• food packaging and pizza boxes
• certain cosmetic and personal-care products

The issue arises once these substances enter the body. The kidneys and liver are barely able to eliminate PFAS. Instead, the compounds build up in the blood and organs – a process experts call bioaccumulation.

“PFAS practically never leave the body. Every additional exposure adds another layer to an already growing chemical account.”

Studies have linked PFAS with hormonal disruption, a weakened immune system and a higher risk of certain cancers, among other effects. Debate has generally centred on drinking water and human exposure. The new Italian research instead puts wildlife – and birds of prey in particular – in the spotlight.

Birds of prey as nature’s early-warning system for PFAS

Published in the specialist journal Toxicology Mechanisms and Methods, the study assesses data from several parts of the world. Its central question is: what role can birds of prey play in improving understanding of how PFAS spread through the environment?

The conclusion is clear: falcons, eagles and other raptors are highly suitable sentinel species – in other words, biological warning systems.

“Birds of prey sit at the top of the food chain. What accumulates beneath them will sooner or later end up in their bodies – where it can be measured.”

Researchers detected PFAS in almost every type of tissue examined:

• blood
• liver
• eggs
• feathers

This broad distribution demonstrates how deeply these chemicals penetrate the body. Feathers and eggs can be collected with comparatively little disturbance, which is particularly important when monitoring rare species without placing further pressure on them.

Fish-eating birds of prey face a higher risk

One key finding of the study is that raptors feeding largely on fish have substantially higher PFAS concentrations than species that hunt solely on land.

These include, for example:

• white-tailed eagles
• ospreys
• fish-hunting buzzards or kites in wetland habitats

The reason is that many types of PFAS first enter water through industrial wastewater, sewage treatment works and rainwater. From there, they accumulate in sediment, small aquatic organisms, fish and ultimately the predators that feed on them.

“The food chain acts like a chemical amplifier: what begins at a low level in water ends up in birds of prey at concentrations many times higher.”

The research therefore highlights the severe PFAS burden affecting aquatic ecosystems in particular. Long-chain compounds such as PFOS, which are extremely persistent and especially prone to bioaccumulation, are a major concern.

Why birds of prey are such informative indicators

The researchers’ decision to use raptors as indicators is strategically sound. Several factors combine to make them especially useful:

• At the top of the food chain: They eat fish, small mammals or other birds that may already be contaminated.
• Long lifespans: Many raptors live relatively long lives, giving pollutants sufficient time to accumulate.
• Large territories: They range across extensive areas and can therefore reveal contamination over a wide geographical scale.
• Easy to monitor: Nesting sites and eyries are often observed for years, so the available data are comparatively strong.

Measuring PFAS in birds of prey therefore provides more than a snapshot of an individual body of water. It offers an integrated view of chemical contamination across the animals’ entire habitat.

Older PFAS are declining, but new compounds are emerging

Some of the best-known PFAS substances are now tightly regulated or banned in many countries. Their concentrations are indeed falling slightly in certain regions. At the same time, however, newer and less researched compounds are appearing to replace the older substances.

These “replacement PFAS” are often shorter-chain compounds and are claimed to break down more quickly. Early data, however, indicate that they may also be problematic and can likewise travel long distances through water, air and food chains.

“Industry is moving from familiar to unknown molecules, yet nature sees little difference: the contamination remains, it merely changes its chemical face.”

The Italian study consequently warns against a false sense of security from declining levels of individual legacy chemicals. Without long-term monitoring using clear standards, it is difficult to identify which new PFAS are gaining importance in the background.

Long-term monitoring rather than a brief snapshot

The researchers advocate comprehensive, multi-year programmes that monitor birds of prey systematically. Ideally, these would be combined with other animal species, such as fish, seals or small mammals. This would make it possible to compare different levels of the food chain.

A practical strategy could include:

• selecting sensitive species in contaminated regions
• taking regular samples of blood, feathers and, where possible, eggs
• using standardised laboratory methods to make results comparable internationally
• linking the data with information from drinking water, soils and food

Such schemes would not only reveal where contamination hotspots are located. They could also provide an early indication of whether bans or tighter requirements in chemicals legislation are genuinely working.

What PFAS mean for people in Europe

The findings from Italy are directly relevant to German-speaking countries. Germany, Austria and Switzerland also contain areas with heavily contaminated groundwater and drinking water. PFAS enter the environment there through industrial parks, airports and former firefighting training sites.

Birds of prey in these areas could be subject to contamination patterns similar to those described in the study. Testing them would provide a clearer picture of how far PFAS have already advanced through local food chains.

Bioaccumulation, toxicity and cancer risk: what the terms mean

Many of the key scientific terms surrounding PFAS may sound abstract, but they describe very tangible processes:

• Bioaccumulation: Repeated intake of small amounts of PFAS over a long period. The body breaks down very little, so levels rise gradually but continuously.
• Biomagnification: Concentrations increase at every level of the food chain. From plankton to fish to birds of prey, the contamination multiplies.
• Toxicity: Depending on the type of PFAS, the liver, immune system or hormonal system may be harmed, often even at low concentrations.

For people, this means that regularly consuming contaminated food or water leads to a measurable PFAS level in the blood over the years. The mechanism is similar in birds of prey – but it is often faster and produces higher peaks because they occupy the top of the food web.

Practical steps: what researchers, policymakers and consumers can do

The Italian study does not offer a simple way out, but it does identify clear areas for action:

• Research: Expand monitoring programmes involving birds of prey and publish open databases for international comparisons.
• Policymakers: Introduce stricter PFAS limits in water, act quickly on newly suspected substances, and support PFAS-free alternatives in industry and everyday products.
• Consumers: Shop consciously, look for PFAS-free coatings and textiles, and follow local information about drinking-water quality.

Birds of prey provide more than abstract laboratory figures. High levels of PFAS in their feathers, eggs and organs show that contamination has already reached the heart of ecosystems we are meant to protect – bringing it closer to our own health as well.