Take a lesson from Borneo -- go easy on the bug spray

Q: You said pesticides can be hazardous if used carelessly. How serious a problem is this?

A: It can be quite serious, especially if the pesticide is particularly toxic, as DDT was when it was being used.

In the 1950s, the World Health Organization sent supplies of DDT to Borneo to fight mosquitoes that spread malaria among the people. The mosquitoes were quickly wiped out. But billions of roaches lived in the villages, and they simply stored the DDT in their bodies.

One kind of animal that fed on the roaches was a small lizard. When these lizards ate the roaches, they also ate a lot of DDT. Instead of killing them, DDT only slowed them down. This made it easier for cats to catch the lizards, one of their favorite foods.

About the same time, people also found that hordes of caterpillars had moved in to feed on the roofing materials of their homes. They realized that the lizards that previously had kept the caterpillar population under control had been eaten by the cats. And now, all over North Borneo, cats that ate the lizards died from DDT poisoning. Then rats moved in because there were no cats to control their population. With the rats came a new danger: plague. Officials sent out emergency calls for cats. Cats were sent in by airplane and dropped by parachute to help control the rats.

We don't use pesticides as dangerous as DDT anymore, but we still have to be careful. Just because the EPA approves of a pesticide doesn't mean it is safe. It has pulled nearly 100 pesticides off the market that were previously available to the public. The problem is that many of the pesticides available now haven't been around long enough for us to know if they are dangerous or not in the long run.