A drug used as a painkiller in cattle in Asia has driven three species of vultures to the brink of extinction, the first time a pharmaceutical has been documented as the cause of an ecological disaster. The discovery was made by a team of scientists working with the Boise-based Peregrine Fund. The Peregrine Fundґs international program director Rick Watson called the discovery alarming.
"This may not be the only pharmaceutical impacting wildlife," Watson said.
More than 95 percent of populations of the vultures have disappeared since 1996, an extinction spiral not seen since the loss of the great auk and the passenger pigeon in the 19th century. The birds could go extinct in a matter of months, not years, if nothing is done, Watson said. Extinction of the vultures could be disastrous in Asia because they clean up dead livestock. Hindus consider cattle sacred and do not eat them. Muslims do not eat cattle that die from sickness. Cattle are often medicated in South Asia, then die and are left for scavengers. Vultures eat the contaminated beef and develop kidney failure, the Peregrine Fund team found.
Tom Cade, founder of the Peregrine Fund, said the rapid crash of the three vulture populations is eerily similar to the decline of the peregrine falcon and bald eagle populations due to DDT in the 1960s, reports &to=http://www.idahostatesman.com' target=_blank>IdahoStatesman.com
A study in 2002 by the United States Geological Survey found traces of many different pharmaceuticals and "personal care products" - including steroids, insect repellents and many others - in the American water supply. The effect of these traces is unknown, but the concern is about the unexpected. One laboratory study suggested, for example, that antidepressants like Prozac could trigger spawning in some shellfish. "I think what it actually says is that we really need to look systematically at the use of pharmaceuticals for veterinary purposes," Dr. Lovejoy said. He added, "It does raise a question of whether we should be looking more closely at the trace chemicals from human use." The next step was to survey veterinarians and the sellers of veterinary drugs to find which medications were regularly used in livestock, since domestic animals formed a major portion of the vultures' diet.
Because an overdose of diclofenac can cause kidney damage in humans, the drug seemed to be a likely cause of death in the vultures. Further tests established that there were residues of diclofenac in dead vultures. The researchers then conducted experiments that showed that the amount of diclofenac a vulture might ingest from a carcass could kill it within days, according to &to=http://www.nytimes.com' target=_blank>NYTimes.com