did ddt really kill birds

Crushed eggs. Dead eagles. Birth defects. The 1960s and ‘70s were a trying time for the American environment, thanks to DDT. The effects of the toxic pesticide became obvious quickly despite agricultural companies’ prolonged attempts to give it a clean bill of health. With the release of Rachel Carson’s 1962 Silent Spring—published in part as a series in the New Yorker the same year—news of DDT’s toxic effects spread. As public awareness peaked, the debate caught fire, causing President Kennedy to order a scientific inquiry.

What the public didn’t—and still might not—know is that the fight against the chemical wasn’t over even when the horrifying facts came to light. In fact, the battle raged on and victory was only secured a decade later, thanks to the rise of the Environmental Defense Fund, a group of scientists formed explicitly to fight DDT. Its this battle that Charles Wurster, one of the founding members of EDF, explains in his new book, DDT Wars, which came out earlier this month. He leaves no detail uncovered—especially when it comes to describing the complexities of navigating the U.S. legal system—as he outlines the surprising victories that arose from the endeavor. Wursters story is that of the scrappy underdog triumphing over powerful businessmen and politicians—a timeless struggle that offers lessons and insights still relevant today.

The fact that bald eagle and other bird-of-prey populations declined as a result of DDT (or dichloro-diphenyl-trichloroethane) g. ospreys, brown pelicans) is now widely acknowledged by the majority of biologists. But at first, it was unknown how DDT affected the thinning of the eggshells, which prevented these birds from reproducing. In the end, the connection was established by looking again at the impairment’s description.

The persistent finding of high body burdens of DDT metabolites was the initial connection between DDT and declining populations of bald eagles and other birds of prey. Put differently, there was a co-occurrence between the declining bird populations and DDT, the potential cause. Additionally, a comprehensive exposure pathway to birds based on DDT body burden was demonstrated. Extensive DDT toxicity testing on adult bird mortality, however, did not find any connection. This suggested that the proposed mechanism, toxicity, was implausible. But the impairment was not lethality; rather, it was the decline in prey-bird populations. It was necessary to develop a new conceptual model that took into account additional mechanisms that might cause bird population declines. Upon reexamining the entire analysis, it was evident that the tested species had demonstrated a comparatively higher tolerance to DDT exposure than the wild-dwelling species. Additionally, the lethality observed in these tests would not accurately represent the success or failure of reproduction as a result of DDT exposure.

Field observations eventually provided a plausible explanation for the possible mechanism of bald eagles and other prey birds’ reproductive failure caused by thinning eggshells. Laboratory experiments showed that DDE could cause eggshell thinning. Based on the stressor-response relationship, field investigations demonstrated that exposure to DDE, a metabolite of DDT, was sufficient to have an impact on numerous bird species. Taken together, these results offered points of evidence suggesting that DDT may thin eggshells and lower reproductive success, which is a more targeted impairment than population declines in birds.

In the US, DDT was outlawed for most uses in 1972. Bald eagle and other bird-of-prey populations gradually recovered in the years after the prohibition. There is compelling evidence that the use of DDT was the real cause of the declines in the populations of bald eagles and other birds of prey, as evidenced by the recovery of bird populations following the ban on the chemical’s use.

The Long Island environmentalists escalated their conflict in September 1967. To persuade the organization to join the battle against DDT, they broke into the National Audubon Society’s biannual convention, which was taking place in Atlantic City, New Jersey, that year. Other leaders disagreed with the idea, but Audubon’s vice president at the time, Roland Clement, did. Thus, the nine-member Long Island unit went rogue and independently established the EDF in October 1967 in order to bring their scientific concerns to court. It was “born out of the frustration of environmentalists who couldn’t get the system changed.” and the strong belief that our concept would succeed because we had witnessed it succeed,” Wurster writes.

Following a string of successes, EDF decided it was time to expand nationwide. Even after the Department of Agriculture placed restrictions on DDT use in 1969, the chemical was still present. In addition to taking up the battle nationally, EDF joined forces with Audubon and other conservation organizations to resolve regional disputes. Wurster weaves together all these tales in a dramatic exposition. He adds scientific support to each scenario, enhancing it, and provides a detailed account of each trial and decision. Because of these numerous layers, the story keeps getting better as it gets closer to the conclusion.

The small citizen-aided survey in Hanover proved to be seminal. After crunching the data on SUV-sized computers in the college’s basements, Wurster and his team published two major studies, one in Science and one in Ecology. Hanover heeded the birds’ morbid warning; the following year they opted for methoxyclor, which unlike DDT, doesn’t persist in soil or inflict damage on the entire food chain.

Wurster’s book is incredibly timely and relevant because of this connection; although the story is ancient, the methods of battle and the fervor needed for such a crusade are still relevant today. Even the biggest battles will be open for grabs if the contemporary environmental movement can emulate the tenacity and perseverance of the EDF founders.

What the public was unaware of, and possibly still is, is that the battle against the chemical continued even after the horrifying details became public. In actuality, the fight went on, and it wasn’t until ten years later that the Environmental Defense Fund—a group of scientists founded specifically to oppose DDT—rose to prominence. Charles Wurster, one of the original members of EDF, describes this conflict in his recently released book, DDT Wars, which was released earlier this month. He doesn’t omit any information, particularly when outlining the difficulties of navigating the U S. legal system—as he describes the unexpected successes that resulted from the effort Wurster’s tale is one of the tenacious underdog defeating strong businessmen and politicians—a timeless conflict that provides lessons and insights that are still applicable today.


Did DDT harm birds?

The fact that DDT (or dichloro-diphenyl-trichloroethane) played a role in the decline of bald eagle and other bird-of-prey populations (e.g., ospreys, brown pelicans) is now commonly appreciated among most biologists.

Was DDT really that bad?

Following exposure to high doses, human symptoms can include vomiting, tremors or shakiness, and seizures. Laboratory animal studies show DDT exposure can affect the liver and reproduction. DDT is a possible human carcinogen according to U.S. and International authorities.

Did DDT kill robins?

It all started when people wanted to protect American elm trees from a deadly disease. They sprayed the elm trees with an insecticide that contained a powerful chemical called DDT. The chemical pesticides ended up killing backyard robins, but long after the elm trees were sprayed.

Has DDT killed anyone?

That last point isn’t easy to document in the U.S. During the go-go DDT years there was one case of a young girl who drank from a prepared DDT solution, and died a short time later. The incident was a tragedy, but not unique for the 1950s and 1960s.