Effects of Persistent Organic Pollutants on Top Predators

Top predators are often most affected by persistent organic pollutants due to bioaccumulation. This occurs because each step of the food chain acquires a little more of the pollutant (a shrimp eats polluted algae, a small fish eats many shrimp, a big fish eats many small fish, and a polar bear eats many big fish) and the top predator ends up with the highest concentrations of all. Often these effects take the form of problems in reproductive development and susceptibility to disease due to inhibition or incorrect development or various immune and organ systems. As humans we are already beginning to see signals of health problems from endocrine disruptors (further discussed in another post) in the form of decreasing sperm counts, increased levels of defective sperm, smaller penises, undescended testicles, underdeveloped or inter-sex genitals, higher incidence of hermaphrodites, increased levels of some cervical and vaginal cancers, and higher incidence of some birth defects. From studies on the environment, other species, and ourselves, we know that endocrine disruptors are all around us, and that they are very harmful to just about any species they come into contact with. These chemicals fundamentally threaten the survival of affected species due to their reproduction-associated effects.