"No longer can people simply expect a stronger pesticide to eliminate health risks or a better disposal process to halt toxic waste problems created by various industrial polluters."

IN 1999, Belgium suffered a public health crisis that toppled a government, sent food exports plunging, and captured world press attention. The problems began in January, when two synthetic organic compounds--furans and polychlorinated biphenyls (PCBs)--were mixed with animal oils and fats destined for feed. Investigators do not know what caused the initial contamination, but they suspect used transformer oils. Both compounds have effects similar to dioxins, persistent substances that are one of the most toxic group of chemicals known.

About 10 feed manufacturers sold their products to nearly 1,700 farmers in Belgium, who gave it to countless chickens, pigs, and cows. Although the exposure in each bite of feed was minuscule, these contaminants collect in animal fat, concentrating to much higher levels. By early February, chickens were dying and egg production at many of the farms had declined. In mid March, the Ministry of Agriculture found PCBs and furans in chicken fat and eggs at several hundred times the legal and safe limit.

Despite the evidence, national authorities waited another month to warn the public and neighboring nations of the dangers, a decision that came back to haunt them on election day. By the end of May, retailers throughout the country pulled from their shelves all poultry and egg products, including mayonnaise, cakes, and cookies; farmers slaughtered any animals suspected of carrying the poisons; and governments from Australia to the U.S. banned importation of Belgian animal products. Consequently, Belgian farmers lost nearly $500,000,000 in sales, and many politicians were ousted in the June election.

This widely reported case is just the tip of a much larger problem that affects people and wildlife in every corner of the globe--the spread of persistent organic pollutants (POPs) like dioxins and PCBs, and their infiltration into food and water, the environment, and people's bodies.

POPs are a group of insidious synthetic compounds that share four common properties: they are toxic, accumulate in the food chain, persist in the environment, and have a high potential to travel long distances from their source. The properties that made some of these chemicals so appealing to industries in the first place have made their control extremely difficult. Rather than being soluble in water, POPs have an affinity for the fat tissue of living organisms. Animals and people accumulate these toxins in their bodies, primarily from the food they eat. As the chemicals move up the food chain, they bioaccumulate, meaning that each link or species in the food chain takes up the previous link's exposure, adding it to their own and magnifying the effects.

POPs are extremely durable. Even where these chemicals have been banned for 20 or more years, as in the U.S., they persist in soil, water, and body fat. Many health problems can be traced to chemical releases that ended long before the victims were born. Moreover, because they are highly reactive to temperature and pressure, POPs can hitchhike on global wind and water currents, migrating from warmer to colder climates and contaminating people as far away as the Arctic Circle.

As the 21st century begins, the legacy of the chemical revolution is clear: From plastics to pesticides, POPs are ubiquitous. Some of these synthetic compounds have helped raise levels of food production, protected human health, and allowed for many of the conveniences of modern life, but these advances have come at a high price. All of us now have about 500 anthropogenic chemicals in our bodies--potential poisons that did not exist before 1920. Many of these are POPs, with PCBs and DDE--a highly persistent breakdown product of the notorious insecticide DDT--the most commonly detected.

While scientists have yet to understand fully the long-term health impacts of POPs, they have begun to confirm some of the initial effects. Several POPs are thought to be hormonally active compounds that impersonate natural chemical messengers and throw the body's endocrine and immune systems into disarray. Others are associated with delayed intellectual development, reproductive problems, and cancers. From gulls and fish to seals and eagles, species throughout the food web have shown signs that they are imperiled by POPs. Unless actions are taken to reduce and eventually eliminate POPs, these synthetic time bombs will continue to menace life on Earth.

Today, a new chemical substance is discovered about every nine seconds of the working day. Most remain laboratory artifacts. On June 15, 1998, chemists identified the 18,000,000th synthetic chemical substance known to science. Of the millions currently recognized, fewer than 0.5%--possibly 50,000 to 100,000--are actually used in commerce. The vast majority of these are organic substances, meaning they contain carbon, an element essential to life. In certain molecular combinations, however, carbon can herald trouble.

Synthetic organic chemicals are largely a 20th-century creation. They were first manufactured on a large scale during the 1930s and have been growing in volume ever since. Some of these "everyday" synthetic organic chemicals are not of direct environmental concern, such as those in pharmaceuticals, cosmetics, and food additives. More problematic are the numerous compounds introduced into the environment in large quantities, such as dyes, detergents, additives in plastics, organic metals, antifouling paints, and pesticides.

Of about 1,000 recognized environmental contaminants, about half contain chlorine, which tends to impart stability and persistence to the molecule and make it more...

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