Early on in their history, the development of resistance to chemical pesticides became a significant issue. The rapid multiplication rates of single-celled or other simple organisms makes it clear that such a problem is inevitable, but the speed with which resistance occurs has often surprised observers. Resistance to DDT was a major problem only five years after its introduction. Today multiple pesticide resistance is common, and new pesticides, like new antibiotics, are regularly produced by industry to address this problem. The WHO further estimates that at least 3 million persons are poisoned annually, many of whom are children.
Pesticides can be remarkably persistent in biological systems.
The U.S. Environmental Protection Agency has conducted the National Human Adipose Tissue Survey since 1976, measuring toxic compounds in human fat. These findings are particularly disturbing because DDT has been banned in the U.S. since 1972. Pesticides are also found far afield, in ecosystems considered pristine and far from active pesticide use. Osprey eggs in the Queen Charlotte Islands, polar bear fat in the high arctic, and the blubber of whales in all the oceans of the world are contaminated with pesticide residues , even though all these creatures live far from point sources of pesticide application. Highest on the food chain, human breast milk is of great concern because of high levels of bio-accumulated pesticides.