BC researchers find toxic chemical 4NP in endangered killer whales

A toxic chemical often used to make toilet paper was prevalent among an array of concerning chemicals found in the bodies of orcas and endangered southern resident killer whales recently studied by British Columbia-based researchers.

Part of pulp and paper production, 4-nonylphenol (4NP) is a compound listed as a toxic substance in Canada. It can interact with the nervous system and influence cognitive function, according to a research team composed of the Institute for the Ocean and Fisheries at the University of British Columbia (UBC), the British Columbia Ministry of Agriculture and Food, and Fisheries and Oceans Canada.

4NP, which is also used in soap, detergents and textile processing, can enter fish-bearing waters from sewage treatment plant processes and industrial runoff, suggests the new study. The chemical can be ingested by smaller organisms and move up the food chain to reach top predators such as killer whales.

4NP was found in 46% of the total pollutants identified. The researchers were also the first to look at the transfer of pollutants from mother to fetus in one southern resident pair. They found that all pollutants identified were transferred in the womb, and 95% of 4NP transferred from mother to fetus.

“Very little is known of both the prevalence and health implications of 4NP as it has been studied in few marine mammals,” said first author Kiah Lee, who undertook the research as an undergraduate at UBC. “This study is the first to find 4NP in killer whales,” she added.

Researchers analyzed skeletal muscle and liver samples from six southern resident killer whales and six Bigg’s whales stranded along the coast of B.C. from 2006 to 2018.

While 4NP was the most prevalent, just over half the pollutants identified by the researchers belong to the group of chemical compounds known as perfluoroalkyl and polyfluoroalkyl substances, or PFAS. The most common pollutant of the PFAS group was 7:3-fluorotelomer carboxylic acid, or 7:3 FTCA.

“This compound has not been found in B.C. before and it was found in killer whales, which are top predators. That means the contaminants are making their way through the food system,” said co-author Dr. Juan José Alava, principal investigator of the Ocean Pollution Research Unit at the Institute for the Oceans and Fisheries.

There are currently no restrictions on the production and use of 7:3 FTCA, but one of its potential parent chemicals is on a list of toxic substances proposed to be recognized as new persistent organic pollutants (POPs) by the European Chemical Agency under the Stockholm Convention on POPs, an international agreement.

Alva noted that fish such as Pacific salmon are also vulnerable to the chemicals found in the orcas, so there may be implications for human health as well when it comes to seafood.