DDT Byproduct Found in Bald Eagle – Not Related to Its Death

A bald eagle that was tested by the U.S. Fish and Wildlife Service in June 2018 was found to have DDE, a byproduct of DDT, in its liver. This was not the reason for the bird’s death, according to reports received through a Freedom of Information Act (FOIA) request made by WNAV.

On April 25, 2018, three bald eagles and a fox were found in a field in Pedricktown, N.J. One of the eagles and fox died. Two eagles were saved. Pedricktown is located right above the Delmarva Peninsula.

Dr. Erica Mill, the veterinarian who initially treated the birds, emailed WNAV in July of 2018, “Based on the history, clinical signs and response to treatment, I believe these birds were affected by carbofuran. It was certainly some type of cholinesterase inhibitor … I believe the case is still under investigation, so I haven’t been privy to actual findings.”

WNAV submitted a FOIA in this case because of the history of carbofuran use on the Delmarva Peninsula to kill wildlife. The results of the FOIA were received on Friday.

According to the USFWS veterinary pathology examination final report, it is believed the eagle, “died of a bacterial flood infection that resulted in irreversible metabolic disturbances. A cause of death for the fox (LAB-1) could not be determined. Neither animal had detectable toxins that could be associated with mortality.”

The conclusions of the report state, “DDE, a metabolite of DDT, was detected in the liver of this eagle … This likely represents long-term exposure through the diet and is unrelated to the death of the bird.”

“DDT (dichloro-diphenyl-trichloroethane) was developed as the first of the modern synthetic insecticides in the 1940s,” according to the Environmental Protection Agency (EPA) website. “In 1972, EPA issued a cancellation order for DDT based on its adverse environmental effects, such as those to wildlife, as well as its potential human health risks.”

According to the EPA, “DDT is highly persistent in the environment,” with a soil half-life between two and 15 years.

“The half-life of DDT in an aquatic environment is about 150 years,” according to the EPA.

According to the USFWS, “Shortly after World War II, DDT was hailed as a new pesticide to control mosquitoes and other insects. However, DDT and its residues washed into nearby waterways, where aquatic plants and fish absorbed it. Bald eagles, in turn, were poisoned with DDT when they ate the contaminated fish. The chemical interfered with the ability of the birds to produce strong eggshells. As a result, their eggs had shells so thin that they often broke during incubation or otherwise failed to hatch. DDT also affected other species such as peregrine falcons and brown pelicans. In addition to the adverse effects of DDT, some bald eagles have died from lead poisoning after feeding on waterfowl containing lead shot, either as a result of hunting or from inadvertent ingestion. By 1963, with only 417 nesting pairs of bald eagles remaining, the species was in danger of extinction. Loss of habitat, shooting, and DDT poisoning contributed to the near demise of our national symbol. As the dangers of DDT became known, in large part due to the 1962 publication of Rachel Carson’s book Silent Spring, the Environmental Protection Agency took the historic and, at the time, controversial step of banning the use of DDT in the United States. That was in 1972, and it was the first step on the road to recovery for the bald eagle. In 1967, the Secretary of Interior listed bald eagles south of the 40th parallel under the Endangered Species Preservation Act of 1966. Following enactment of the Endangered Species Act of 1973, the Service listed the species in 1978 as endangered throughout the lower 48 states, except in Michigan, Minnesota, Oregon, Washington, and Wisconsin where it was designated as threatened.”

Photo courtesy of Michael Lathroum

In the years since the pesticides DDT and carbofuran were banned, the bald eagle population has bounced back from the brink of extinction.  

On June 28, 2007, the USFWS announced the recovery of the bald eagle and removed it from the list of threatened and endangered species.

Today, it’s estimated there are over 9,700 bald eagle nests in the lower 48 states.

Bald eagles remain federally protected. They still have many threats. In Maryland, 30 or more bald eagles have been killed by carbofuran, a federally banned pesticide, in the past ten years – The EPA fully banned carbofuran in 2009. Lead is another issue. According to American Bird Conservancy, “Millions of birds are poisoned by lead every year. Some birds, like Bald Eagles, accidentally ingest lead shotgun pellets and ammunition fragments when scavenging on carcasses or remains left by hunter.”

Old stock of DDT, carbofuran or any other toxic chemical should be disposed of properly. Do not pour it down sinks, toilets, sewers or street drains. In Maryland, for directions on proper disposal of pesticides, contact the Maryland Department of Agriculture Pesticide Regulation Section at 410-841-5710 or pest.reg@maryland.gov. In New Jersey, contact the Pesticide Control Program of the New Jersey Department of Environmental Protection at 609-984-6507.

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