Perfluoroalkyl substances (PFASs) are man-made chemicals that have found extensive use in consumer products because they repel grease, water, and stains, and they’re heat resistant. They also pose a threat to wildlife. Since that discovery, some PFASs have been phased out of use, but not all of them, and they still work their way into food webs and, subsequently, animals.
The hooded seal is high up in its food web, eating prey that eats prey that eats prey that can get PFASs into their system, increasing the amount of the chemical that gets into the hooded seals. Now, recent research has found that mother seals can pass those contaminants on to their young, both through the placenta and through milk.
While the levels found so far are below the toxic threshold for rodents, and within the expected limits based on findings among other seals, it might be worse for the hooded seals.
Because they only nurse for three to four days, hooded seal milk is extremely rich in lipids, to which PFASs are known to bond. This explains how they manage to pass the contaminants on to their young. Scientists are still not sure what kind of developmental effects these could have on the young seals, who need to put on a lot of weight very quickly in order to survive, because that nursing period is followed by a fasting period.
While the seals seem to be okay so far, that could change, especially as young grow and ingest more prey which are contaminated with PFASs, passing them on to their own offspring. Over subsequent generations the buildup could become quite toxic.
Luckily, by realizing this now, we can begin studying it and, hopefully, learn not only more about the effects of PFASs on animals like the hooded seal, but also how we might be able to mitigate those effects.