Zika Is No Excuse to Bring Back DDT

The pesticide drove bald eagles, ospreys, and other wildlife toward extinction and should only be used as a very last resort.
A woman sprays a DDT aerosol on a window frame to keep insects at bay in 1955. (Photo: Orlando/Three Lions/Getty Images)
Sep 9, 2016· 3 MIN READ
Richard Conniff is the author of House of Lost Worlds: Dinosaurs, Dynasties, and the Story of Life on Earth and other books.

In New England, where I live, this is the time of year when ospreys take their last turn on the waterways before heading south. They’ve mated, reared their young, and seen their fledglings take wing and begin to hunt for themselves. If you are lucky and know your local watering holes, you can still sometimes see them plunging out of the sky and carrying home blood-spangled fish in their talons. It is one of the great spectacles of summer.

But only for a little while longer. Soon the ospreys will migrate 2,500 miles or more, down to the Caribbean or the northeastern coast of South America, where males and females will overwinter separately. They’ll return in March, find their old nest mate (they’re faithful to mates and nest sites, more or less), and begin the ritual once again.

The resurgence of ospreys from near extinction in the 1970s to their modern abundance always makes me think with gratitude of Rachel Carson and the demise of DDT as a standard tool of mosquito control in this country. Her book Silent Spring, published in 1962, first alerted Americans to the risky business of spraying the countryside with as much as 80 million pounds of DDT, an untested chemical, in a single year. One effect of DDT, scientists were demonstrating, was the fatal thinning of the eggshells of ospreys, eagles, peregrine falcons, brown pelicans, and other species. The eggs collapsed under the weight of the nesting parent, and generations were lost. As a result, the osprey population in my home territory, the lower Connecticut River Valley, plummeted from 200 nesting pairs to just two by the early 1970s. The same thing happened to ospreys and other species nationwide. Then the Nixon administration banned most uses of DDT in this country, and wildlife slowly began to recover.

This year, though, my gratitude toward Carson, and my pleasure in ospreys, is complicated by the political response to the devastating birth defects and deaths from mosquito-borne Zika virus, along with the persistent effects of mosquito-borne West Nile virus, which has killed more than 2,000 people since it arrived in the United States in 1999. That’s on top of the 438,000 deaths in 2015 from mosquito-borne malaria, mostly in sub-Saharan Africa.

The Zika outbreak has inspired a proliferation of headlines like the one in a June 6 opinion piece in the New York Post: “The Answer to Zika Is Obvious: Bring Back DDT.” These articles are always written by right-wing political hacks with limited familiarity with science. Apart from the chance to use DDT as a political brickbat, they also have no real interest in public health.

People who have spent their lives working on mosquito-borne disease would tell them, first of all, that mosquitoes had already evolved resistance to DDT in many areas, long before Rachel Carson’s book, in part because manufacturers had enthusiastically promoted its indiscriminate use. Second, the federal government never banned use of DDT for public health issues and had no power to ban it abroad.

Mosquito control efforts began to fail in many countries for lack of funding, brought on largely by complacency and political mismanagement once the malaria threat had been somewhat reduced. If you want a good analogy for what happened, look at the congressional failure earlier this year to allocate emergency funding for Zika control. It was the usual partisan blunder fest: Republicans saddled the bill with provisions promoting the Confederate flag and putting limits on Planned Parenthood. Democrats balked. The public be damned.

Health workers would tell the political hacks, finally, that DDT continues to be used in many countries, and U.S. tax dollars still pay for it through foreign aid block grants. Anti-malaria workers spray DDT on the interior walls of homes as a last resort, when safer pesticides have failed. They do it because it can save babies’ lives. But they also recognize, as one specialist in tropical diseases and pesticides told me, that they are “putting DDT in the mouths of babies through the mother’s milk” and that studies have linked DDT exposure to increased incidence of high blood pressure, reproductive disorders, and Alzheimer’s disease, among other health problems. Those political hacks blindly promoting DDT will tell you it is absolutely safe. So offer to spray it in their houses.

In truth, no one wants to live with DDT when other, safer measures are available. The best way to fight Zika and other mosquito-borne diseases is to start by consulting the latest guidance from the Centers for Disease Control and Prevention, which, by the way, is also underfunded because of congressional bickering and complacency. You’ll note the key phrase “source reduction,” which mainly means applying larvicide to kill immature mosquitoes in local waterways and also getting rid of all the incidental places—spare tires, abandoned pools, random containers—where water accumulates and mosquitoes breed. Repellents, protective clothing, proper window screens, and in problem areas, aerial spraying of less dangerous pesticides can also help. (But just last week, South Carolina learned the danger of aerial spraying even supposedly safe pesticides: One farm lost 2.5 million honeybees on the spot.)

We can have public health without sacrificing our environment, our children’s health, and our wildlife. I will continue to watch my ospreys with pleasure and honor Rachel Carson for helping to save them, and us. The politically motivated call for a return of DDT is just a mindless bid to go back to that blighted era when we thought the only way to save the world was to destroy it.