Behind a frigging pay wall, as usual! Kelly et al. argue in Science that hydrophobicity, the tendency to favor oil over water (to break it down to the simplest explanation) is not the only factor that explains biomagnification. The underlying theory used to be that compounds that can dissolve in water would swiftly degrade (either chemically or biologically) and not be of any concern to humans. Compounds like dioxins, PCB’s, DDT, etc. accumulated in fat tissue of aquatic animals and these were the compounds that would biomagnify through ingestion (eating!). Kelly et al. uncover another pathway that probably made every scientist go “D’uh”! – Apparently, chemicals animals breathe in can also bioaccumulate if they are not cleared efficiently by the lungs. So, air breathing cows, chickens and pigs can also cause significant bioaccumulation of certain compounds. Which ones? I guess you’ll have to pay to find out more, but this Scientific American article adds some context. Turns out, it is about 10000 chemicals, not all of them known to be harmful, but because they were never suspect, their metabolism is unknown.
Well, if anything, it will keep the biomonitoring folks busy for a while!
Global regulators of commercial chemicals apply a scientific paradigm that relates the biomagnification potential of the chemical in food webs to the chemical’s hydrophobicity. However, Kelly et al. (p. 236; see the news story by Kaiser) show that current methods fail to recognize the food web biomagnification potential of certain chemicals. Certain chemicals do not biomagnify in most aquatic food chains, but biomagnify to a high degree in air-breathing animals, including humans, because of low respiratory elimination. Thus, additional criteria for evaluating biomagnification and toxicity in chemicals that biomagnify are required.