The AP reports:
In the coastal redwood forests of central California, scientists trying to unravel the mystery surrounding the reproductive problems of dozens of endangered condors think they have uncovered the culprit: the long-banned pesticide DDT.
The soaring scavengers with wingspans wider than NBA players are tall were reintroduced to the rugged coast of Big Sur in 1997 after a century-long absence. Upon arrival, the birds found plenty to eat, with dead California sea lions and other marine mammals littering the craggy shoreline.
While a good food source, sea lion blubber often has high levels of DDT, a pesticide banned in 1972 that has proven to be a persistent pollutant because it accumulates in bodies of creatures throughout the food chain when animals eat one another.
Once used widely in agriculture, DDT was banned because it is a human toxin considered a possible carcinogen by the U.S. Centers for Disease Control and Prevention.
Kelly Sorenson, executive director of Ventana Wildlife Society and a co-author of a new study on condors, said researchers who spent six years studying their reproductive problems have “established a strong link” to DDT in the birds’ food source…
Another former condor program manager, Noel Snyder, was critical of the DDT study, however.
He said it only looks closely at one potential cause of reproductive problems — DDT — and fails to properly evaluate the potential effects of other contaminants and factors that may be involved and more important.
“DDT is not the only thing that causes eggshell thinning, and the authors of the paper don’t present a significant correlation of DDT with the thinning found, and thus do not do a convincing job of linking DDT with the happenings in Big Sur.”