Canadian researchers have identified “eternal chemicals”, emerging and long-lived pollutants in killer whales. These compounds appear in everyday human products and could affect the health of endangered cetaceans. Their finding in top predators also indicates that they pose a threat to the entire food chain.
Various chemical contaminants appear in the tissues of killer whales, according to a study conducted by researchers at the University of British Columbia (UBC) in this Canadian province. The team analyzed six transient orcas and six southern residents – an endangered population – stranded on shore between 2006 and 2018.
The main compound identified (46% of the total) is 4-nonylphenol or 4NP, used in the manufacture of toilet paper. This substance is listed as toxic in Canada. It is an “emerging pollutant”, potentially dangerous but poorly studied and therefore unregulated.
The study, published in Environmental science and technology, is the first to find 4NP in killer whales. Kiah Lee, a UBC student and first author of the paper, acknowledges that research around this compound still needs to progress: “Developing knowledge about 4NP is necessary to understand the prevalence and impact of this contaminant in killer whales.”.
Co-author Juan José Álava, a researcher at the Institute for Oceans and Fisheries (IOF), points out that 4NP can interact with the nervous system and influence cognitive function: “This investigation is a wake-up call. Southern resident killer whales are an endangered population and pollutants may be contributing to their decline. We look forward to protecting this species“.
For his part, Lee points out that the disappearance of these animals”can have a very serious impact on biodiversity”.
Most of the contaminants identified are perfluoroalkyl and polyfluoroalkyl substances (PFAS), called “eternal chemicals” because they persist in the environment for a long time.
“These substances are found in many products for daily use.notes Lee, “They appear in waterproof materials such as our raincoats, in non-stick pans, containers, fire extinguishers and cosmetics.”.
Many of these compounds are on the list of new persistent organic pollutants (POPs). These are toxic substances, many of which are banned in Canada, that affect the health of living beings and that spread through the physical environment as a result of human activity.
In the analyzed samples, the researchers also detected alkylphenols, a group to which 4NP belongs. In addition to toilet paper, this substance is also found “in herbicides, pesticides and lubricating oils”, explains the scientist.
persistent polluting organisms
The tissues also showed the prevalence of 7:3-fluorotelomer carboxylic acid, or 7:3 FTCA. “We don’t know the human impacts of 7:3 FTCA specifically, but it is part of the group of perennial chemicals, which have been linked to cancer, changes in fertility, and liver damage, among other consequences.Lee alerts.
There are no restrictions yet for this pollutant, but the European Chemicals Agency has included it in its list of toxic substances proposed to be recognized as new POPs, in accordance with the Stockholm Convention on POPs.
This research is also the first to analyze the transfer of contaminants from mother to fetus in a couple from the South. They found that all identified contaminants were transferred in utero and that 95% of 4NP was transferred from mother to fetus.
A threat to the entire food chain
“Emerging contaminants and POPs have already been detected in other mammals and are regularly monitored,” explains the researcher. However, very little is known about its effects on killer whales, so the work “provides important baseline data that can form the basis of future studies.””.
“4NP has not been found previously in British Columbia and has been found in killer whales, which are the top predators. This means that contaminants work their way through the food system.“, says Álava.
This compound can seep into the ocean via sewage treatment plants and industrial discharges, where it is ingested by smaller organisms and moves up the food chain.
“This research is another example of an approach that considers the health of people, animals and the environment, using killer whales as a case study to better understand the potential impacts of these and other compounds on the animal health and ecosystems.“, underlines the other co-author of the book, Stephen Raverty, associate professor at the IOF.
Urgent policy action to regulate ‘eternal chemicals’,
The authors say governments can help protect southern resident killer whales and other endangered marine species. To do this, they demand the cessation of the production of emerging pollutants, including 4NP and emerging POPs such as 7:3 FTCA. In addition, they call for identifying and addressing potential sources of marine pollution in British Columbia and Canada.
Álava warns that it is not just killer whales that are affected by these compounds: “We are mammals and we also eat Pacific salmon, so we need to think about how it might affect our health as well as the other seafood we eat.“.
Lee, K. et al. “Emerging Contaminants and New POPs (PFAS and HBCDD) in Southern Resident Killer Whales and Endangered (Transient) Bigg’s Killer Whales (Orcinus orca)”. Environmental science and technology2022