Lead poisoning destroying wildlife
STILLWATER – Americans have known for a long time about the harmful effects of lead.
Because it can cause anemia, neurological impairment and immune system impairment, lead was banned from paint in 1977, plumbing used for drinking water in 1986 and gasoline in 1996. However, it is still widely used in other applications such as ammunition and weights for fishing tackle.
“While lead has been linked to human health concerns for centuries, only recently has its harm to wildlife been addressed,” said Dwayne Elmore, Oklahoma State University Cooperative Extension wildlife specialist. “Lead is especially problematic for birds, since lead can accumulate in a bird’s gizzard where it is continually ground into smaller particles and readily absorbed into the blood stream.”
The lead particles are absorbed in animal tissue at a faster rate than it can be expelled, making it extremely toxic. When considering an Environmental Protection Agency (EPS) estimate that about 70,000 tons of lead are deposited at shooting ranges each year combined with the additional shot deposited during hunting, the potential threat to scavenging wildlife is evident.
There are several ways birds can consume lead. The most frequent ways are the consumption of contaminated animal carcasses, or lead being mistaken for food and ingested.
“As few as one or two lead pellets can kill waterfowl,” Elmore said. “Even if mortality does not occur, poisoned waterfowl have depressed activity and are more at risk of harvest or predation.”
Consumption of lead shot, bullets or bullet fragments has been a cause of mortality for rare and endangered birds of prey and scavengers. For example, through 1996 there were five states where at least 20 bald eagles died from ingesting lead from carcasses, Elmore said.
Lead ingestion is not limited to just shot as nearly 4,000 tons of lead sinkers are purchased in the United States each year.
While it is hard to estimate the amount of lead deposited into the water, it is assumed that a high percentage of this lead is lost each year.
Swans, geese, ducks, pelicans and loons have a history of mortality from lead weights.
“Loons probably ingest the lead incidentally as they are eating bait off broken fishing lines,” Elmore said. “Some studies have found about half of all loon mortalities were due to lead poisoning. Swans all over the world also have high mortality rates due to lead consumption.”
Nontoxic options are available, and rather than placing regulations on ammunition and weights, voluntary restrictions are preferred. Using steel loads, which are comparably priced to lead, is a viable alternative. For more information on using nontoxic alternatives refer to OSU Extension fact sheet NREM-9015, “Impacts of Lead Ammunition and Sinkers on Wildlife,” at www.osufacts.okstate.edu.
“It’s likely that in the coming years there will be continued restrictions placed on public lands limiting the use of lead ammunition and fishing tackle,” said Elmore.