‘Forever chemicals’ detected in dolphin milk

Researchers have found that a group of chemicals known as PFAS can be transferred from mother dolphins to their nursing calves, adding to the evidence that these persistent contaminants can be transferred from mothers to offspring during early development.   

In a new study from the Texas A&M Superfund Research Center, the researchers examined archived dolphin milk samples collected between 1991 and 1993 to determine the presence of PFAS, often referred to as “forever chemicals.” The Texas A&M Superfund Research Center is a multi-institution center funded by the National Institute of Environmental Health and Sciences and led by the Texas A&M College of Veterinary Medicine and Biomedical Sciences (VMBS).

The study was led by a team from the University of North Carolina at Chapel Hill (UNC) in collaboration with scientists at the VMBS and the Smithsonian’s National Zoo and Conservation Biology Institute.

Scientists have grown increasingly concerned about the detection of PFAS in a wide range of wildlife species. These synthetic chemicals break down very slowly, persist in the environment for years, can travel long distances through water and food webs, and accumulate in water, soil, wildlife and humans over time.

Because dolphins nurse their calves for extended periods and produce milk with a high fat content, studying dolphin milk can help researchers better understand how contaminants move through marine ecosystems and affect developing animals.

“Dolphins are a potential sentinel of global contamination; changes in their health can reveal broader environmental problems that may eventually affect other wildlife and humans,” said Dr. Weihsueh Chiu, a professor in VMBS’ Department of Veterinary Physiology and Pharmacology. “Marine mammals can provide insight into how widespread these contaminants are in the environment.”

The findings raise concerns about how early life exposure to PFAS could affect health during critical stages of growth and development.  

Why early life exposure matters

PFAS, short for perfluoroalkyl and polyfluoroalkyl substances, are widely used in household products and industrial processes, including nonstick cookware, stain-resistant fabrics, food packaging and firefighting foams.

Because these chemicals resist natural degradation, understanding how PFAS move through biological systems is particularly important when considering early life exposure.

In humans, research has shown that breastfeeding can be a significant pathway for PFAS exposure in infants, which is why many regulatory limits for PFAS in drinking water are designed to protect breastfed babies.

“One of the concerns with PFAS exposure is immunotoxicity,” Chiu said. “It can suppress the immune system.”

PFAS exposure has also been linked to a range of potential health effects, including impacts on growth and development, hormone function, and liver health. People and animals can be exposed to these chemicals through contaminated drinking water, food, and everyday products.

Rather than causing an immediate illness in a single individual, these effects can occur across entire populations, slightly weakening immune responses and increasing vulnerability to disease.

Detecting PFAS in dolphin milk

To analyze the dolphin milk samples, researchers used a multidimensional technique combining liquid chromatography, ion mobility spectrometry and mass spectrometry, an approach developed by a team at UNC led by Dr. Erin Baker, a professor and principal investigator on the study.

Traditional chemical tests often rely on identifying specific chemicals using reference standards. In contrast, this technique combines multiple analytical methods, allowing researchers to detect a wider range of compounds and confirm their identities with greater confidence.

“Traditional testing methods typically look for a limited number of known PFAS compounds,” Baker said. “By combining multiple analytical techniques, we can identify a much broader range of chemicals and be more confident in what we are detecting.”

This approach also allowed researchers to detect PFAS compounds that are not typically included in standard targeted testing, providing a more complete picture of environmental exposure.

Because the technique can detect multiple chemicals, it may also help scientists identify environmental contaminants following industrial accidents or environmental disasters, when the types of chemicals present may not be immediately known.

To better understand what the detected PFAS levels might mean biologically, the researchers compared the findings with existing knowledge about PFAS exposure in humans.

Because PFAS are known to remain in the human body for years, much of the current research on their health effects has been conducted in people. Using those data as a reference point, the researchers applied a scientific scaling approach that accounts for differences between species to estimate what similar exposure levels might represent for dolphins.

Several of the PFAS detected in the dolphin milk samples were present at concentrations that could be considered concerning when interpreted using these scaled human health benchmarks.

A global contamination problem

Although the study focused on dolphins, the findings reinforce broader concerns about the global reach of PFAS contamination.

“This is a global contamination problem, and it doesn’t have borders,” Chiu said.

As research continues, scientists hope studies like this one will help clarify how PFAS contamination spreads through marine ecosystems and identify potential risks to wildlife during critical stages of development.