J32 a pregnant Southern Resident killer whale breaching.
Pregnant J32. Photo copyright Traci Walter. All rights reserved.

According to a recent study by a team of Canadian government scientists and university researchers, evidence of newly-found contaminants in the Southern Resident killer whales highlights a lack of regulation and understanding of the possible impacts on these long-lived top predators, especially for their calves. Their evidence reveals for the first time that these endangered killer whale moms transfer dangerous chemicals to their calves even before birth.

Scientists tested for 49 different contaminants in the liver, tissue, and muscle of 12 killer whales (six Southern Residents and six Bigg’s killer whales, aka transients) found deceased and stranded between 2006 and 2018.

The results showed similar levels of contaminant exposure regardless of age or gender. However, four calves under one month of age had a higher contaminant load than the older calves and even “exceeded those observed in the eldest individual (Bigg’s killer whale).”

Previous studies have shown that when the Southern Resident killer whales are malnourished, contaminants stored in their blubber become “mobile” in the bloodstream and may be released during nursing. Scientists proposed “the influence of contaminant maternal transfer processes,” including lactation, could account for the higher levels in these newborns.

In 2014, a heavily pregnant J32 Rhapsody washed ashore in British Columbia. A necropsy (whale autopsy) found that her calf died during birth, which led to her mother’s death. Samples collected from this tragedy enabled scientists to test an unborn calf for the first time. This revealed that 15 contaminants had transferred between J32 and her calf, leaving the calf with levels higher than her mom’s.

J32 prior to necropsy.
Photo courtesy of Global News.

A necropsy of J32 found that her calf died during birth.

"Maternofetal transfer of contaminants is important to understand as calves are sensitive to toxicity in development and are at increased risk of pollutant exposure before birth."

What are these harmful contaminants?

Per- and poly-fluoroalkyl substances—collectively known as PFAS—are also known as ‘forever chemicals,’ as some predict that they won’t break down in the environment for thousands of years. (Learn more in this helpful primer here.)

This family of toxic chemicals makes products resistant to stains, grease, soil, and water in a wide variety of household products and industrial processes.

"In humans, PFAS contaminants have been reported to alter immune and hepatic functions, disrupt glucose metabolism, and cause reproductive risks."

Scientists found evidence of 14 out of 40 PFAS chemicals they tested for, accounting for half of all contaminants across all tissue samples. One, known as 7:3 FTCA—not previously detected in killer whales—was predominant and the dominant forever chemical transferred from J32 to her unborn calf.

"These results raise concerns regarding pathological implications and potential impacts on fetal development and production of a viable neonate [newborn calf]."

Alkylphenols are a group of chemicals currently classified as “contaminants of emerging concern.” They are primarily used in herbicides, pesticides, lubricating oils, and detergents. From the four Alkylphenols contaminants researchers specifically tested for, 4NP at 96.7% was the most dominant in several tissue samples” and the first time documented in killer whales.

Unlike other killer whales of the Pacific Northwest, this endangered population primarily forages in urban waters where they—and their prey—are exposed to pollution sources such as runoff, wastewater, and sewage effluent. The scientists noted that “toilet paper is a significant source of 4NP.”

In humans, 4NP can “mimic or disrupt estrogen hormones.” Testing revealed 4NP in J32’s unborn female calf showed “maternal transfer rates as high as 95.1%.” The researchers noted that these chemicals “have been shown to alter the endocrine system, which may create difficulties in the birthing process.”

Triclosan is another contaminant of concern, used as an antibacterial agent in “toothpaste, soaps, detergents, toys, and cleaning products.” This was its first detection in killer whales, found in all 12 animals, including J32s unborn calf.

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While the effects of these ubiquitous chemicals are studied in humans, little is known about their impact on killer whales. Still, as long-lived social mammals, similar adverse effects on reproduction, hormones, nervous system, physical development, and cognitive function would likely be the same as in humans, perhaps greater. Not only do these chemicals accumulate in the whales’ blubber, but their transfer up the food chain to these top predators results in even higher concentrations, a process known as biomagnification.

The challenge to eliminate these forever chemicals from manufacturing and our contaminated environments will be immense. Yet there is something we can do to help the Southern Resident killer whales now—make sure they have enough to eat. Nutritional stress—due to seasonal shortages of Chinook salmon—lies behind a pregnancy failure rate of nearly 70% and increases their vulnerability to pollution. We should see six or seven births per year, not seven in total over the last five years, so finding these dangerous contaminants in this endangered population—potentially further reducing successful births—is of great concern.