A team of wildlife researchers, led by a West Virginia University graduate student, has found evidence of long-term lead exposure in birds in eastern North America. The discovery suggests that lead permeates the region’s ecosystems to a previously unrecognized degree, which could have profound implications on human health.

Birds have long been environmental bellwethers, charting the health of natural resources on which humans depend and, like the canary in the coalmine, alerting us to impending problems. For years scientists have used data about bird populations as warning signals about our ecosystems.

In a paper published online today (March 19) in Environment International, researchers from WVU, Virginia Polytechnical University, Michigan State University and the USDA Forest Service reported that 100 percent of birds sampled in their study had bone lead levels indicative of long-term lead exposure.

Shannon Behmke, lead author and graduate student in wildlife and fisheries resources in the Davis College of Agriculture, Natural Resources and Design said that the findings raised concerns about the state of the natural environment in the region.

“This is an indicator – a particularly strong one – that lead is far more pervasive in our environment than previously thought,” Behmke said. “It is important for us to understand the meaning of these findings on a larger scale and the potential impact of this lead on the health of ecosystems, wildlife and humans.”

“With mild exposure, lead causes a number of nearly lethal effects such as neurological damage, tissue and organ damage, and reproductive impairment,” explained Jesse Fallon, a doctor of veterinary medicine and graduate of WVU’s Division of Animal and Nutritional Sciences master’s degree program. “At more toxic concentrations in birds, lead causes a litany of problems including anemia, disturbances of cellular metabolic functions, and neurological injury leading to blindness, seizures, weakness and death.”

This is an indicator – a particularly strong one – that lead is far more pervasive in our environment than previously thought.

In today’s study, researchers evaluated tissue from 108 American black vultures (Coragyps atratus) and turkey vultures (Cathartes aura), obligate scavenging birds native to eastern North America.

“These birds are ideal subjects because they are widespread and serve as useful environmental sentinels for the region,” said Todd Katzner, Behmke’s thesis advisor in wildlife and fisheries resources and currently a wildlife biologist with the U.S. Geological Survey. “As scavengers, one of their most important food sources is hunter-killed game, which is also common in human diet.”

The research team collected samples from the birds’ livers, a tissue whose lead concentrations are indicative of short-term lead exposure, and femurs, which are indicative of long-term lead exposure. Additionally, isotope ratios were used to home in on the source of lead exposure.

“The data showed that only some birds had liver lead levels indicative of recent exposure,” Katzner said. “However, what is new is we found that all of the birds showed signs of prolonged lead exposure from multiple sources.”

Isotope ratios recorded in the study demonstrated that lead exposure appeared to be consistent with lead used in rifle ammunition and lead emitted from coal-fired power plants and zinc smelting operations.

Katzner said that all of those sources are common in eastern North America. He also noted that the prevalence of lead in this avian population combined with evidence that exposure was from multiple sources makes it likely that other species in the region, including humans, could also be at risk for exposure.

Adam Duerr, a wildlife biologist at WVU and co-author on the manuscript, said, “Additional research should be conducted to determine what is needed to protect avian populations, other wildlife and people from potential exposure to lead.”

“Our findings illustrate that lead permeates to a previously unrecognized degree in the environment of eastern North America, which is a system that both humans and vultures depend on,” Katzner said. “Therefore, this study calls attention to an issue that may directly affect human health as well as our nation’s ecosystems.”

Additionally, Behmke said that the study demonstrated that future studies should look for lead in the right places.

...this study calls attention to an issue that may directly affect human health as well as our nation’s ecosystems.

Past avian toxicology studies typically used soft-tissue, feathers and blood measurements as reliable indicators of short-term lead exposure. Behmke said that by themselves those indicators missed the chronic exposure reported here. Samples from femurs provide data to assess long-term lead exposure.

“Our study brought to light the importance of alternative sampling systems for both wildlife and humans to understand long-term exposure to lead,” Behmke said.

Behmke is a member of WVU’s Peace Corp Masters International Program in the Davis College. The paper was co-authored by Fallon, Katzner and Duerr, as well as Andreas Lehner and John Buchweitz of the Diagnostic Center for Population and Animal Health at Michigan State University.

By Marissa Sura
University Relations/News

-WVU-

ms/03/19/15

CONTACT: David Welsh, Davis College of Agriculture, Natural Resources, and Design
304.293.2394, David.Welsh@mail.wvu.edu

Follow @WVUToday on Twitter.

Editor’s note: Citations and abstract for the study

“Chronic lead exposure is epidemic in obligate scavenger populations in eastern North America”

Authors: Shannon Behmke, West Virginia University; Jesse Fallon, Virginia Polytechnical University; Adam Duerr, West Virginia University; Andreas Lehner, Michigan State University; John Buchweitz, Michigan State University; and Todd Katzner, West Virginia University and USDA Forest Service

Published: Online on March 18 and in print in volume/issue: 79C, pp. 51–55, Environment International

DOI: 10.1016/j.envint.2015.03.010

Web: http://www.sciencedirect.com/science/article/pii/S0160412015000616

Abstract: Lead is a prominent and highly toxic contaminant with important impacts to wildlife. To understand the degree to which wildlife populations are chronically exposed, we quantified lead levels within American black vultures (Coragyps atratus; BLVU) and turkey vultures (Cathartes aura; TUVU), two species that are useful as environmental sentinels in eastern North America. Every individual sampled (n = 108) had bone lead levels indicative of chronic exposure to anthropogenic lead (BLVU: = 36.99 � 55.21 mg Pb/kg tissue (�SD); TUVU: = 23.02 � 18.77 mg/kg). Only a few showed evidence of recent lead exposure (BLVU liver: = 0.78 � 0.93 mg/kg; TUVU liver: = 0.55 � 0.34 mg/kg). Isotopic ratios suggested multiple potential sources of lead including ammunition, gasoline, coal-fired power plants, and zinc smelting. Black and turkey vultures range across eastern North America, from Quebec to Florida and individuals may traverse thousands of kilometers annually. The extent to which vultures are exposed suggests that anthropogenic lead permeates eastern North American ecosystems to a previously unrecognized degree. Discovery of an epidemic of chronic lead exposure in such widespread and common species and the failure of soft-tissue sampling to diagnose this pattern has dramatic implications for understanding modern wildlife and human health concerns.