A team of researchers has found that chemical pollutants may be slowly poisoning polar bears. The chemicals are being passed to cubs through milk. Past research on seals showed that the levels of persistent organic pollutants were safe but this new study shows that it’s a different story for polar bears. The findings are in a paper that was just published in the journal Environmental Toxicology and Chemistry.
Persistent organic pollutants (POPs) are toxic chemicals that don’t easily break down in the environment. This allows them to quickly build up to dangerous levels. Carnivorous animals tend to be especially vulnerable because they may eat prey animals that were exposed to the pollutants. Over time, consuming prey items that have been poisoned leads to the bioaccumulation of toxins in the predator’s body. Although many countries have banned the use and production of POPs, they continue to persist in environments throughout the world—including the Arctic. Previous research has showed that Arctic seals have measurable concentrations of POPs in their systems and can pass it onto their babies through milk. While the seals had concentrations below the safety threshold, there had been no research on how POPs might affect Arctic animals higher up on the food chain.
Scientists compared POP concentrations among different Arctic animal species, including fish, seals, and polar bears. Their results confirmed previous research on seals—while seals have measureable concentrations of POPs, it’s not enough to be harmful. On the other hand, the researchers measured toxic concentrations of POPs in polar bears. Bear cubs were especially vulnerable to toxic effects since the chemicals were being concentrated and passed down through their mother’s milk. The research team concluded that most animals in the Arctic ecosystem were exposed to safe levels of POPs but that polar bears were potentially being poisoned. This is a serious problem since polar bears are already at risk of extinction.
The team’s findings emphasize the importance of researching ways to manage environmental POPs. The contaminants may be harming polar bears, which are already struggling with climate change and food shortages.
Villa et al. Risk of POP mixtures on the Arctic food chain. Environmental Toxicology and Chemistry (2017).