High levels of PCBs are also found in trout, carp, catfish, bass, bluefish and mackerel. PCBs are particularly harmful to devel-oping fetuses and infants because it can impair development. The pesticide DDT was banned in the 1970s but it is still being found in the flesh of fish. PCBs, mercury, DDT, dioxin and scrombold can t be destroyed by cooking or freezing fish. Another health concern is the level of heavy metals in seafood.
Shellfish carry toxic levels of lead, cadmium, arsenic and other heavy metals.
The World Health Organization has concluded that there is no absolutely safe level of mercury in the human body. Fish is the main source of dietary mercury in our bodies and almost all of it is in the toxic form, methylmercury. A typical can of tuna contains 15 micrograms of mercury. Fish also contain natural toxins such as ciquatera and scrombold which, like PCBs, mercury, DDT and dioxin, can t be destroyed by cooking or freezing. Ciquatera poisoning causes nausea, vomiting, cramps, headaches and extreme fatigue.