Orca whales were discovered with a toilet paper chemical in their livers and skeletal muscles. It’s just the ‘tip of the iceberg’ for one of the most contaminated marine mammals in the world.

• Scientists found Southern Resident and Bigg’s killer whales with 4-nonylphenol in their livers and skeletal muscles.

• 4NP is associated with the production of toilet paper.

• The scientists also discovered PFAS – known as forever chemicals – in the orcas’ bodies.

Killer whales are among the most infested marine mammals in the world.

The strains are full of chemicals – from “highly toxic and carcinogenic” PCBs to the infamous insecticide DDT.

Now a group of scientists has discovered another worrying chemical – and it’s associated with toilet paper.

Scientists from the University of British Columbia, British Columbia Ministry of Agriculture and Food, and Fisheries and Oceans Canada found a chemical known as 4-nonylphenol — along with dozens of other chemicals — in the liver and skeletal tissue of 12 dead Southern Resident and Biggs killer whales.

The chemical 4NP belongs to a group of chemicals known as alkylphenols, which UBC researcher Juan José Alava described to Insider as “highly toxic.”

Although Alava and other researchers who spoke to Insider noted that it’s too early to conclude with certainty how killer whales are affected by 4NP, their discovery raises alarm.

The amount of 4NP found in the killer whales, which was usually higher in the blood-rich liver tissues, reached exceptionally more in one calf.

“These contaminants can, in principle, affect reproduction and development, and we know, based on the weight of evidence, affect cognitive function and also the nervous system,” Alava said. “So we’re talking about contamination that is harmful to the environment and harmful to this species of killer whales.”

Alava said the exact source of 4NP affecting whales is unknown, the chemical is mainly found in sewage sludge and wastewater treatment plants. It is also used in detergents and cosmetic products.

In addition to 4NP, more than half of the contaminants discovered in the killer whales belonged to a class of chemicals known as PFAS — commonly referred to as forever chemicals because of their difficulty in breaking down in the environment. PFAS can be found in drinking water, fish and in trace amounts in human blood and can increase the risk of diseases such as cancer and liver disease in humans.

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The study authors noted that it was the first time 7:3-fluorotelomer carboxylic acid, a type of PFA, had been found in a Pacific Northwest killer whale. Alava noted that 7:3 FTCA has not been found before in British Columbia and may indicate that the contaminant is making its way through food systems.

‘They’re just being killed by 1,000 cuts’

While Biggs and Southern Residents are both threatened by the possibility of extinction, scientists are particularly concerned about Southern Residents, whose numbers are not growing.

In addition to habitat loss, climate change and fishing gear entanglement, Southern killer whales are struggling with their food supply.

Overfishing means there is not enough food. And contaminants in the environment mean that if there is food, it could very well be full of chemicals. Because killer whales eat so much, they usually have a higher concentration of chemicals compared to their smaller marine counterparts.

Southern residents rely on Chinook salmon to supplement their diet. The discovery of chemicals in their system means that Chinook salmon also have contaminants in their system – a warning to people who also consume the salmon.

But more than that, a lack of proper food supplies affects killer whale reproduction, Deborah Giles, a scientist and director of research at the nonprofit organization Wild Orca, told Insider.

Giles’ own research found that 69% of southern resident killer whale pregnancies were unsuccessful, with 33% failing late in pregnancy or immediately after birth.

“And those females that lose their calves are deficient in nutrients, which of course works to increase the impact of chemicals,” Giles said.

Chemicals are also transferred between mothers and fetuses. The UBC study, which looked at a southern resident known as J32, found that all of the chemicals found in her were transferred to her fetus. J32 died in 2014 while trying to deliver her fetus, Giles noted.

“They’re just really really being killed by 1,000 cuts,” Giles said.

‘This is just the tip of the iceberg’

“Too few” killer whales had been screened to determine the extent of 4NP contamination in killer whales, the authors noted, but getting even this amount of data on killer whales — which are usually studied after they’re dead — is an impressive task.

Alava told Insider that due to limited access to orca organs, he doesn’t believe he or the team he worked with will be able to do another autopsy study like this anytime soon.

The lack of data leaves many unanswered questions: Why are some species less affected by certain chemicals than others? What role do these chemicals play in endangering this species? How many chemicals will researchers continue to find? And which of the dozens of harmful chemicals found in the environment should scientists and regulators focus on when trying to save the species?

Irvin Schultz, an executive with NOAA’s Environmental Chemistry Program, who spoke to Insider about the research, also said that because these specific chemicals have not been screened before, more needs to be done to determine their true impact on the species.

“It’s definitely more than trace levels,” Schultz said. “So it’s something that grabs your attention, and maybe it’s definitely something to keep measuring and tracking.”

Schultz, whose lab focuses on measuring other contaminants — such as polyaromatic hydrocarbons that occur naturally after burning fossil fuels — says it’s also important to keep in mind that killer whales are exposed to so many more contaminants.

“The real value for this study is providing some data for compounds that haven’t been monitored or measured as much,” Schultz said.

And scientists like Giles continue to pay attention to the other unknown chemicals killer whales may be retaining in their bodies.

“I suspect the more we look, the more we’ll find related to chemicals, man-made chemicals that find their way through the food web and into our apex predators like whales,” Giles said. “And I think what’s terrifying to me is that I believe this is just the tip of the iceberg as to what we’re going to find.”

Read the original article on Business Insider