40 years after their ban, these toxic chemicals are able to eliminate killer whales – Mother Jones

In January 2016, a 20-year-old killer whale, known as "Lulu", was stranded on the shores of Scotland after being caught in a rope. Although her deadly death was probably directly caused by the strings, toxicologists later reported that she had extremely high levels of polychlorinated biphenyls (PCBs) used until the 1970s to make plastics, adhesives , paints and industrial equipment.

Research shows that PCBs can cause infertility in marine mammals and, of course, researchers have found that Lulu has never given birth to a calf, although having exceeded the average age of 30 years. age of reproduction. Pathologists, one of the last killer whales in the UK, also concluded that chemicals may have played a role in the decline of their pod. And now, new research shows how PCBs can be harmful, posing a greater risk than ever before for killer whales.

PCBs are chemicals banned by the Environmental Protection Agency in 1979 after being associated with cancer, liver damage and congenital anomalies in humans and humans. animal. But at that time, we, the humans, had already made up to 300 billion pounds, some of which were transported into the ground, air and water via landfills or dumps. accidental spills. In some cases, it has been applied directly to the roads to minimize dust. PCBs have persisted in the environment for decades – slowly accumulating the marine food chain, from phytoplankton to large predators like Lulu.

Although scientists have known for a long time that PCBs can cause health problems in animals, no one has known until now the effect of these chemicals on certain animals. populationslike Lulu's pod, and how seriously they threaten the survival of an entire species like killer whales.

The new research, published Thursday in the journal Science, mapped the projected effect of PCBs on 19 killer whales – and the results are not encouraging. The researchers conclude that more than half of these populations are threatened by PCBs and that many populations are at "high risk of collapse over the next 100 years". In general, the most threatened groups already have small populations (see table below). live near places where the use of PCBs is historically high, such as the United States and Europe.

Among the 19 populations, some at moderate and high risk live close to home: off the coast of Hawaii and Alaska. Others live near the United Kingdom, Japan, Greenland, Brazil and the Canary Islands.

Jean-Pierre Desforges, postdoctoral researcher at the University of Aarhus and lead author of the study, tells Mother Jones His team chose to focus on killer whales because, as high-end predators, they run the greatest risk because their prey can also contain large amounts of PCBs. "Killer whales are unique in that they feed on seals, other whales, which makes them vulnerable to contamination," he said.

What's so dangerous for killer whales and other animals is that removing the environment from PCBs will require "global efforts," says Desforges, because the world has failed to remove chemicals from the soil and some water. "It is estimated that more than 80% of global PCB stocks are not yet destroyed," the authors conclude at the end of the document. "And at the current rate of PCB disposal, many countries will not achieve the 2025 and 2028 targets agreed under the Stockholm Convention [Persistent Organic Pollutants]A 2001 international treaty to eliminate chemicals such as PCBs from the environment. (According to the EPA, sediments loaded with PCBs can be dredged, covered with clean sediment or blocked by a barrier, but are left to natural biodegradation, a process that could take decades longer.)

Jim Meador, an aquatic toxicologist with the National Oceanic and Atmospheric Administration, who is not affiliated with the study, says that Mother Jones. But he also points out that the projections are based on models. No model can take into account all the factors of the environment. "It's like the weather [forecasts], He said, adding that it's nothing. It's a prediction of the future. "

Although the authors note that this study only examined the effect of PCBs on killer whale populations, it did not include other stressors such as noise pollution, lack of food and other chemical pollutants. in the oceans. "If this class of chemicals can cause such significant damage, just think of the effects that multiple stressors could have," said Desforges.

John Moore, an Assistant Administrator of the EPA at the time, New York Times In 1987, less than 10 years after the ban on chemicals, the process of removing PCBs from the environment "will be measured in a few decades." Thirty years later, this feeling is still true.