Sure, I would be happy to. Thank you for the question. I'll start with wildlife, and then I'll answer the question about human health.
When it comes to wildlife, there's no doubt that organisms are exposed. This includes animals at every level of the food web. In Lake Ontario, for example, where I live, we sometimes find fish with more than 100 pieces of microplastics in their gut contents. They're exposed, and in certain locations, they're exposed to a high concentration.
A number of laboratory studies have looked at the effects on organisms. This includes zooplankton, organisms at that lower level of the food chain, and from molluscs like mussels and clams and oysters all the way up to fish. If people synthesize that work and put it together, they can look at the risk to the species. For example, if I put this information together, what is the concentration that harms 5% of the species within the environment? That concentration is around 100 to 120 particles per litre. That concentration is found in some parts of our Great Lakes already.
When it comes to microplastics, we still have a lot to learn in terms of the different types of plastics out there, but we know that the concentrations we find in nature in high concentrations can be toxic to freshwater and marine species.
When it comes to human health, we know that there are microplastics in our drinking water. We know that there are microplastics in the seafood we eat as a result of microplastics leaving the gut and going into parts of the organism that we eat. We don't yet know how it impacts human health. That's still a bit of a black box.