Chemicals involved:
-DDT
-Mercury
-Cesium 137
Harmful chemicals that start at the bottom of the food chain continue up to the higher end of the food chain. The chemicals multiply as the organisms at the top of the food chain consume (eats) the organisms of the lower part of the food chain. The organisms at the top of the food chain will suffer the most with the largest doses of the chemical.
For example, in the 1970's, DDT was used as an "insect repellent" mainly used to kill off mosquitoes and prevent malaria. Humans sprayed DDT on all kinds of crops without knowing the harmful effects. Over time, they found that DDT affected various organisms, in particular birds. The shells of the bird eggs were thinning, causing them to break. The population of animals such as crayfish, daphnids, sea shrimp and many species of fish also declined. Not only did it affect birds and small animals, but also humans. Research showed that DDT harms the female reproductive systems, and is carcinogen; cancer causing.