Killer whales have been 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 killer whales with 4-nonylphenol in their livers and skeletal muscles.

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

• Scientists have also discovered PFAS — known as forever chemicals — in the bodies of killer whales.

Killer whales are some of the most contaminated marine mammals in the world.

The species are full of chemicals, from “highly toxic and carcinogenic” PCBs to the notorious 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, the British Columbia Ministry of Agriculture and Food and Fisheries and Oceans Canada have found a chemical known as 4-nonylphenol – along with dozens of other chemicals – in the liver and skeletal tissue from 12 dead Southerners and Bigg’s orcas.

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

Although Alava, and other researchers who spoke to Insider, noted that it’s too early to definitively conclude how orcas are affected by 4NP, their discovery raises some alarms.

The amount of 4NP found in killer whales, which tended to be highest in blood-rich liver tissue, reached exceptionally high levels in a calf.

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

Alava said the exact source of 4NP affecting the whales is unknown, the chemical can mostly be 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 orcas belonged to a category of chemicals known as PFAS, commonly referred to as eternal chemicals due to their difficulty 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 that 7:3-fluorotelomer carboxylic acid, a type of PFA, had been found in a Pacific Northwest orca. Alava noted that FTCA 7:3 has never been found in British Columbia before and could indicate that the pollutant is working its way through food systems.

‘They just got killed by 1,000 cuts’

Although Biggs and Southerners are both threatened with the possibility of extinction, Southerners, whose numbers aren’t growing, have scientists particularly concerned.

In addition to habitat loss, climate change, and entanglement in fishing gear, southern resident orcas struggle with their food supply.

Overfishing means there isn’t enough food. And contaminants in the environment mean that when there is food, it could very well be full of chemicals. Because orcas eat so much, they usually have a higher concentration of chemicals than their smaller marine counterparts.

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

But more importantly, the lack of a good supply of food is affecting orca reproduction, Deborah Giles, a scientist and director of research at the nonprofit Wild Orca, told Insider.

Giles’ research found that 69% of pregnancies among southern resident killer whales were unsuccessful, with 33% failing towards the end of the pregnancy or immediately after birth.

“And those females who are losing their calves are nutritionally deficient, which obviously adds to the impact of the 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 give birth to her fetus, Giles noted.

“They really get killed by 1000 cuts,” Giles said.

“This is just the tip of the iceberg”

“Too few” orcas have been screened to determine the extent of 4NP contamination in killer whales, the study authors noted, but even getting this amount of data on orcas — which are usually studied after their deaths — is an impressive task.

Alava told Insider that due to limited access to orca whale organs, he doesn’t believe that either he or the team he worked with will be able to perform a necropsy study like this again anytime soon.

The lack of data means that there are still 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 in the environment should scientists and regulators focus on when trying to save the species?

Irvin Schultz, a manager of NOAA’s environmental chemistry program who spoke to Insider about the research, also said that because these particular chemicals haven’t been examined before, more needs to be done to determine their true impact on the species.

“It’s definitely more than levels of tracks,” Schultz said. “So that’s something that catches your eye, and maybe it’s definitely something to continue to measure and track.”

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 far more contaminants.

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

And scientists like Giles continue to pay attention to what other unknown chemicals killer whales might contain in their bodies.

“My guess is that the more we look, the more we’re going to find as far as chemicals are concerned, man-made chemicals that are making their way through the food web and into our apex predators like whales,” Giles said. “And I think that’s the scary part for me is that I think this is just the tip of the iceberg as far as what we’re going to find.”

Read the original article on Business Insider