May 15, 2015
By Glynis Board
A new study out of West Virginia University finds that lead poisoning in vultures is way more prevalent than expected. Researchers say the source of the lead is ammunition and coal-fired power plant emissions—prompting one researcher to liken vultures to the canaries miners once used to gauge if a coal mine was safe or not.
“Bone acts as a sink,” said doctor of veterinary medicine, Jesse Fallon. He explained that bodies can mistake lead for calcium and suck it into the bone where it will stay for a long time, even years.
Fallon is the Director of Veterinary Medicine for the Avian Conservation Center of Appalachia which is a nonprofit that treats and rehabilitates injured, ill, or orphaned wild birds. Through this work and ecotoxicology training, Fallon has become an expert on lead poisoning.
"The presence of lead in these vultures is indicative of a threat that humans face," said researcher and now wildlife biologist with the U.S. Geological Survey, Todd Katzner. "We view these vultures as indicators, as canaries in the coal mine."
He was involved in the recent vulture study helping researchers understand the physiological ramifications of lead exposure, and how lead moves through the body and where to look for it.
That’s why Shannon Behmke cut into the femur bones of just over 100 vulture carcasses—to look for lead.
“Reading more of the literature I understood that most of these vultures would have lead exposure or signs of lead exposure within their organs, but the extent to which we found it in the femurs was incredible,” Behmke said.
Behmke, the lead author of the study, found evidence of significant lead exposure in every bone she examined, which indicates persistent exposure throughout the birds’ lives. Vultures typically live about ten years, so this study is an indicator of environmental exposures over the last decade. But that’s not all she was able to determine.
“We did isotope ratio analysis,” Behmke said. “It pretty much gives ideas of where the sources could be of this lead. And what we found were isotope ratios similar to those found in lead ammunition and also lead emission from coal fired power plants.”
There were a couple other sources, and isotope ratio analysis of lead is an inexact science, but Behmke says ammunition and coal-fired power plants seem to be the major sources of lead.
“The presence of lead in these vultures is indicative of a threat that humans face,” said researcher and now wildlife biologist with the U.S. Geological Survey, Todd Katzner. “We view these vultures as indicators, as canaries in the coal mine.”
Katzner points out that vultures are obviously breathing the emissions that we breath. West Virginia had coal-fired generating units at 20 locations in 2005. Three have been retired, and American Electric Power says three more are supposed to go off line next month.
Katzner also says it’s also important to think about lead ammunition, especially in a state that harvested about 40,000 bucks during last year’s firearms season alone. Vultures often eat discarded gut piles. Most of those animals were killed with lead ammunition. Since that lead is making its way into the birds, Katzner says, chances are, it’s also probably making its way onto our tables. But even low levels of lead are dangerous.
Fallon explains that low levels of lead exposure can affect the body neurologically, in tissue and organs, and by impairing reproductive abilities. He explains that higher levels of lead exposure can cause anemia and neurological injury which can lead to blindness, seizures, weakness and even death. Fallon says this is certainly true for birds, but also for humans, especially children who are developing a nervous system.
The Centers for Disease Control reported that “at least 4 million households today have children living in them that are being exposed to high levels of lead.” CDC says no safe blood lead level in children has been identified. And since lead can affect nearly every system in the body, and leave no obvious symptoms, it frequently goes unrecognized. In a recent report the CDC wrote that compelling evidence shows that low levels of lead exposure are associated with IQ deficits, attention-related behaviors, and poor academic achievement.
Photo top: Balck vulture. Credit: Shannon Behmke. Bottom right: Shannon Behmke, lead author on study of lead exposure in vultures. Credit: WVU