Since the 1950s, per- and polyfluorinated alkyl substances (PFAS) chemicals have been used in industrial and consumer products for their heat, stain and water resistance properties. As more has been revealed about the potential for these chemicals to bioaccumulate in animals and humans, research that helps us understand the ways in which people are exposed to these chemicals has become increasingly important.
Led by Dr Matt Taylor of NSW Department of Primary Industries, the results of the study have been published in renowned international journal Food and Chemical Toxicology. We asked Karl for an overview of the study and what it means for the long-term management of this emerging group of contaminants.
The study focused on the impact that cooking methods–frying, baking and boiling–can have on PFAS contamination levels in fish and crabs. Why are studies like this important?
To understand the risks to humans from hazardous chemicals, it’s important to have accurate estimates of the amount of contaminants people are exposed to. Typically, risk assessments for food rely on measurements of chemical concentrations present in foods in their raw state.
In some cases, chemical contaminants can be degraded during cooking or transferred to cooking media (water or oil), causing the concentration of contaminants in the food to reduce. In other cases, changes to the food’s structure during cooking can make chemical concentrations increase. Studies like this help us to understand whether cooking is a viable option for limiting people’s exposure to emerging contaminants like PFAS.
Why was seafood chosen for the test?
Seafood is known to be a source of PFAS exposure for people. Many PFASs are transported efficiently in water and are taken up by animals, so seafood is an important food group to consider, especially for people who regularly consume fish from contaminated areas. Previous studies of the effect of cooking on seafood have given conflicting results for changes to PFAS concentrations, so it was very important to conduct a high-quality study to provide reliable answers.
Give us a quick overview of the research methodology and results
The principle is very simple. Important seafood species were obtained from a contaminated estuary and cooked by the same methods that people would normally use in their homes. The PFAS concentrations before and after cooking were measured by Sandra Nilsson and other experts at the Queensland Alliance for Environmental Health Sciences (University of Queensland). The keys to this study were the quality assurance in handling the seafood, using relevant cooking techniques and the high-quality of chemical analyses. These produced very reliable results that allow risk assessors to have confidence in applying the outcomes.
The results were mixed, even when comparing species that are closely related – what does this mean for how we tackle the issue of PFAS?
The most important PFASs to consider for this study were PFOS and PFHxS, as these concentrations were the highest in the samples and these are contaminants that have received considerable attention in Australia and overseas. Concentrations of PFOS and PFHxS did not change in flathead (fish) during baking or frying. However, concentrations in school prawn did increase during boiling, which may have been due to moisture being lost from the prawns during cooking. In other words, the amount of PFOS or PFHxS probably didn’t change, but the concentration changed because the prawns weighed less after cooking. The paper published in Food and Chemical Toxicology discusses other possible explanations. The important outcome of the study is that concentrations of key PFASs were not shown to decrease during cooking, meaning that cooking is not a useful means to reduce risks of exposure to PFASs from seafood.
RPS works with organisations all over Australia to investigate PFAS contamination and implement strategies for reducing its impact. What’s the most rewarding thing about your job?
I love the diversity of my work, being able to provide expert advice on a range of issues relevant to the investigation, management and remediation of chemical contamination. Working in a high-performing team is extremely satisfying, as is knowing that I am helping to find effective solutions for emerging contaminants such as PFASs. I also greatly appreciate being encouraged by RPS to be involved in research such as this cooking study.