Chemicals used in the production of toilet paper have been found in the bodies of orcas around British Columbia, according to a new study.

Scientists with the University of British Columbia, B.C.'s Ministry of Agriculture, and Oceans Canada analyzed tissue from six southern resident killer whales and six Bigg's whales, also known as transient killer whales, along B.C.'s coast from 2006 to 2018 and found that chemical pollutants are prevalent in killer whales.

One of the most common pollutants found in killer whales' bodies was 4-nonylphenol or 4NP, which is often found in toilet paper.

Juan José Alava, the co-author of the study and principal investigator of the ocean pollution research unit at UBC's Institute for the Oceans and Fisheries, said Thursday the findings left him and other researchers "shocked and saddened."

He said the toxic chemical substances could affect killer whales' hormone systems, disrupting physiological function and making them susceptible to diseases.

In addition to toilet paper pulp, 4NP is also used in soap, detergents and textile processing and is listed as a toxic substance in Canada.

The chemical accounted for 46 per cent of the total pollutants identified in the whales.

A group of toxic pollutants known as "forever chemicals" — since they can last for a long time in the environment — made up just over half of the contaminants found in the whales, researchers said.

"Forever chemicals are the groups of contaminants that can cause immunotoxicity, making marine mammals like killer whales more susceptible to pathologies and emerging infectious diseases,'' Alava said.

The chemicals are used in food-packaging materials, stains, cookware and fire extinguishers.

One such compound, known as 7:3 FTCA, had not been found in B.C. before but was the most common of the forever pollutants found in the whales' bodies.

The findings were published last month in the journal Environmental Science and Technology.

Dr. Peter Ross, a senior researcher with the B.C.-based Raincoast Conservation Foundation, says he is "saddened but not surprised" by the findings.

He notes that whales are vulnerable to such chemicals because they live for a long time and are at the top of the food chain.

The 2001 Stockholm Convention banned persistent organic pollutants such as PCBs (polychlorinated biphenyls) and DDT, he says, but less is known about a new generation of chemicals that tend to be "less persistent or magnify to a lesser degree" in the food chains that support endangered southern resident killer whales.

"With 1,000 new chemicals on the Canadian market every year, we have a lot of emerging contaminants where we really don't know what to expect and what we might find when we, in fact, look at something like a killer whale," he said.