VANCOUVER — Decades after a chemical plant spewed DDT throughout St. Louis, Mich., the harmful insecticide lingers, reaching acutely toxic levels in birds and their eggs, researchers reported November 13 at the annual meeting of the Society of Environmental Toxicology and Chemistry.
Led by environmental toxicologist Matt Zwiernik of Michigan State University in East Lansing, researchers found that the town’s birds suffer from seizures and lesions, and had extremely low survival rates.
Of 29 dead birds collected between May and August 2013, 10 had gross organ abnormalities, including brain and liver lesions. Levels of DDT and its breakdown products topped 4,700 micrograms per gram of weight in the birds’ organs. Those concentrations are among the highest levels ever recorded in wild birds.
In eggs, concentrations of DDT and its breakdown products ranged from about 4,000 to 650,000 nanograms per gram of weight. Any eggs with greater than 63,000 nanograms per gram of weight had no chance of hatching, the researchers found. In robins’ nests, less than a quarter of chicks hatched.
The U.S. Environmental Protection Agency is now working to clean up the town, which was home to the DDT-producing Velsicol chemical plant until 1978. The use of DDT was banned in 1972.
Editor’s note: This story was updated at 5 p.m. on November 17, 2014, to correct that the measured egg concentrations included both DDT and its breakdown products, not just DDT.