Human exposure to persistent organic pollutants (POPs) occurs in several ways—in foods, mostly as pesticide residues; occupationally, as among farm workers who spray pesticides on crops; and through accidents, including leaks in indoor storage areas (6, 261). POPs are organic compounds that have long lives in the environment and undergo physical, chemical, and biological changes over time.

What makes POPs especially dangerous is that they tend to accumulate in the fatty tissues of animals and humans. They climb the food chain, increasing in concentration as one organism eats a lower one, lodging eventually in human beings and such top predators as polar bears and wolves. Once in the human body, they mimic the function of steroid compounds, such as hormones, leading to the disruption of the endocrine system. Such disruption can damage reproductive health, causing sterility, birth defects, cancers, and spontaneous abortions, among other adverse effects (147).

POPs also can travel great distances in air or water. Greenlanders, for example, live thousands of miles from any known source of the pesticide hexachlorobenzene (HCB), but they have 70 times as much of this pollutant in their bodies as people from temperate areas of Canada (130, 134). The highest concentrations of one of the most potent POPs—polychlorinated biphenyls (PCBs)—have been found in Inuit people in the remote Arctic. Their levels are several hundred times higher than those reported anywhere else (134). This carcinogenic chemical has been found in elevated concentrations in the blubber of whales and seals, which are important food sources for the Inuit people.

In Denmark epidemiologists have noted a threefold increase in testicular cancer over the past 50 years, an increase that they attribute to proliferation of toxic chemicals, such as POPs, in the food chain (261). Some think that high levels of DDT may predispose women to breast cancer (28).

Global negotiations are now underway to ban or greatly limit use of 12 dangerous compounds, mostly pesticides. The first international meeting to discuss a global treaty to limit POPs took place in Montreal in July 1998. Currently, a framework treaty is being negotiated under the auspices of the United Nations Environment Program (UNEP). It is expected to be ready for signature by the end of 2000 (6). By signing the treaty, nations will commit themselves to concrete steps to phase out production and use of these chemicals by a specified date.

R. Faidutti/FAO

In Eritrea a farmer sprays pesticide on his fields. Increasingly, toxic chemicals are entering the food chain, with serious effects on human health. Global negotiations are underway to limit use of 12 dangerous chemical compounds, mostly pesticides.