Revisiting the DDT Debate

Power to the Peeples is an exclusive Earth911 series written by Bob Peeples, our resident chemical engineer and Program Manager of Earth911’s sister site Beaches911. Bob combines his extensive knowledge of the environment and how things work with an off-the-cuff sense of humor.

In 1962, Rachael Carson penned Silent Spring, an indictment of the pesticide industry that held out DDT as her poster child of our tendency to launch chemical products as panacea without careful and complete research. The result of the book was an equal and opposite reaction, as DDT was summarily banned, also without complete environmental or health impact studies.

This is typical of knee-jerk politics, and has no place in real science. Don’t get me wrong, Carson is a hero to us environmentalists, mostly because she may have been the greatest driving force in the subsequent creation of the Environmental Protection Agency, and raised public awareness of our tendency to spoil and waste the resources of our children.

My greatest concern has always been with the broad, pendular swing in public opinion that resulted. We shot right from panacea to poison and suddenly found ourselves at a polar opposite in common public opinion.

I don’t agree at all with environmentalism as religious faith. When we cease to analyze, and instead rely only on blind faith, then we cease to advance science as a society. When we set our policy toward wide swings of mitigative rather than adaptive solutions, we also force ourselves into an out-of-control oscillation in public policy.

Let’s look at DDT again. Here’s a great anti-DDT message, but founded on two faith-based (and fallacious) arguments:

1. The first leap of faith was that DDT had killed off a predatory wasp that controlled a caterpillar that ate thatched roofs in Borneo. Perhaps so, but the best way to control the caterpillars is also probably DDT. Maybe some of the caterpillars just missed the death express train by hiding in cocoons through the previous treatment and could use another application. Better yet would be to take an integrated pest management (IPM) approach of reintroducing the wasp. After all, DDT does not develop new pests; this caterpillar was probably eating roofs long before DDT.
2. The second argument is based in much more obvious fallacy. There has never been any scientific study demonstrating any mammalian or avian health impact from DDT traveling up the food chain. Jumping to the conclusion that the loss of Borneo cats could only be due to the use of DDT not only lacks any evidence of critical thought, but completely ignores a vital consideration. Both Bubonic Plague and the Typhus that they speak of are spread through arthropod (flea, tick, etc.) mammalian parasites or flying insect vectors, and cats are exposed to those same vectors when they confront the rats. Is it perhaps possible that the abrupt planetary ban of DDT is exactly what led to the demise of these cats?

I can’t help but see a twofold solution in the kitty drop: Sending 14,000 unwanted American feral cats to South African homes that will welcome them, while getting them out of my front yard and saving my plants from being torn up for use as cat toilets—that makes pretty darn good sense to me.

There is another discussion (also not my own) of DDT effects that speaks to the polar opposite of the opinion of those faithful masses in the grassroots environmental movement.

So why was DDT ultimately banned? It was traveling up the food chain and most certainly destined for that most sacred of all: mother’s milk. What we failed to ask ourselves is, “So what is the problem with that?”

Everybody spins things to make their argument, and I wouldn’t be a responsible scientist if I took either position as gospel. I don’t know whether DDT is good or bad. I understand that about a million people die every year from malaria alone because we have not yet developed an alternative vector control strategy that is as safe, viable, effective and affordable as DDT. I also realize that DDT and its metabolites were climbing the food chain, and we don’t know what the impact of that is.

I just try to lay both ends out for honest and balanced scrutiny, because real science is about examination and study. I would prefer to see more of the middle instead of these periodic quantum shifts between diametrically opposed paradigms, though.

That’s really all that I have to say; just think about the information that is fed to you. The most dangerous thing that can be fed to you is not DDT, but political mendacity.