Persistent Organic Pollutants and Pesticides

POPs -- persistent organic pollutants -- have caused such international concern that the United Nations has organized consultations to produce a convention in 2001 for controlling use of the "dirty dozen", 12 of the most worrisome of these compounds.

• Eight are pesticides, including some of the most widely used over the past 60 years: aldrin, chlordane, DDT, dieldrin, endrin, heptachlor, mirex and toxaphene.
• Two are mainly industrial chemicals: hexachlrobenzene (also a pesticide) and
• The other two are unintended byproducts of other activities, including natural processes like fire: polychlorinated dibenzo-p-dioxins (PCDDs), also known as dioxin, and heptachlor-polychlorinated dibenzo-furans (PCDFs), referred to often as furans. They are often discharged by pulp mills that use chlorine as a bleaching agent.
  
  What makes them such a problem? There are fears their use can cause edocrinal damage resulting in birth defects. They also dissipate slowly in the environment and bioaccumulate through the food web (increasing the dangers among consumers). However, they have proven very useful in pest control over the years, before their dangers were known, and a number of tropical countries with stubborn problems from diseases such as malaria or an economy based on pesticide-dependent production of commodities such as cotton have been reluctant to sign on to a blanket ban.