Many toxic compounds are highly soluble in fats but almost insoluble in seawater.
In comparison to the ocean of water, the ocean of fat is minuscule. It is therefore incapable of diluting down to harmless levels the fat-soluble toxic substances that humans have already manufactured and will soon have dumped into the environment. I will focus on just one of these groups-the PCBs. They are particularly damaging to vertebrates that live at or near the top of food chains. They are widely used as pesticides, fungicides, herbicides, and insecticides-they are, in fact, biocides that are found in hundreds of products.