Word: ddt
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Despite its resistance to water, DDT is easily soluble in fats and highly susceptible to "biological magnification" as it makes its way up the food chain. A typical case of this kind of metabolic mayhem occurred in Long Island Sound. After some mosquito-infested marshes were sprayed, the DDT was found in the nearby water in a "safe" concentration of .000003 parts per million. Nonetheless, the DDT quickly accumulated in more concentrated form...
Sound's tiny Zooplankton (.04 ppm), then built up further in the fatty tissue of plankton-eating fish (.5 ppm). These small fish, in turn, were devoured by larger fish with yet another increase in DDT concentration (2.0 ppm). By the time the chemical had passed into the bodies of such fish-eating birds as cormorants, mergansers and ospreys its concentration (25 ppm) had increased an astounding 10 million times over the original amount (see diagram...
...DDT also interferes with the reproductive cycle. Adult fish, for example, are able to tolerate relatively high levels of DDT. The fish embryo, on the other hand, dies almost immediately when it begins to absorb the pesticide through the fatty yolk sac. In birds, DDT kills off the young by interfering with the female's egg-laying process. Though the exact chemistry is still obscure, the pesticide apparently sends the mother bird's liver into a frenzy of enzyme production. The excess enzymes break down such steroids as estrogen that are essential to the manufacture of calcium. Lacking...
Airborne Cats. Beyond the danger to fish and birds lies DDT's threat to the whole ecological system. Concentrations of DDT no larger than a few parts per billion in plankton, says Biologist Charles F. Wurster Jr., chief scientific adviser to a New York conservationist group called the Environmental Defense Fund, can substantially hinder the photosynthesis process. On a larger scale, such interference could have a devastating effect, since phytoplankton produces 70% of the earth's oxygen...
...bizarre case of ecological damage from DDT occurred in Borneo after the World Health Organization sprayed huge amounts of the pesticide. The area's geckos, or lizards, feasted on the houseflies that had been killed by DDT. The geckos, in turn, were devoured by local cats. Unhappily, the cats perished in such large numbers from DDT poisoning that the rats they once kept in check began overrunning whole villages. Alarmed by the threat of plague, WHO officials were forced to replenish Borneo's supply of cats by parachute...