The Science and Impacts of Lead Ammunition

Scientific consensus continues overwhelmingly conclude that lead contamination negatively impacts wildlife, the environment, and human health. In many cases, the primary source of lead contamination is from ammunition.

Rachel Carson drew the world’s attention to the environmental and human health impacts of the widespread use of the pesticide DDT throughout the first half of the 20th century in her ground-breaking book Silent Spring, published in 1962.

One of the wildlife species impacted by DDT was the bald eagle (Haliaeetus leucocephalus). By 1963, there were only 417 known nesting pairs of bald eagles in the lower 48 States. Bald eagles were part of what author Michelle Nijhuis calls the “class of 1967” in her book Beloved Beasts, when they were part of the first group of species protected by the precursor to the Endangered Species Act in 1967. They were later protected by the Endangered Species Act when it came into force in 1973. But not everyone wanted eagles protected. As with many misguided and narrow-minded views on predators, many hunting and sporting groups not only opposed eagle conservation in the mid-1900s, but actively shot eagles and encouraged people to hunt them for no other reason than as part of wider efforts at the time to eliminate predators.

But conservation prevailed.

This post is an expansion of my discussion from Episode 15 – Outdoor Narratives, Adventures, and Joy of the Hunt To Eat Show.

Bald Eagle Recovery

By 1997, there were more than 5,000 breeding pairs of bald eagles in the lower 48 states. In 2021, the count put that number at 71,467 breeding pairs, with a total count of about 316,700 individuals.

In 2020, I was participating in a project to put satellite trackers on glaucous gulls (Larus hyperboreus) to track their migration routes. The project involved sitting for hours at the dump in St. John’s, Newfoundland trying to catch gulls in February. As we sat watching for gulls, we counted dozens of bald eagles at any time sitting on the fences and flying around the dump.

With their numbers well recovered, the U.S. Fish and Wildlife Service removed bald eagles from the ESA in 2007.

an eagle flying in the sky
Photo by Frank Cone on

There is some recent good news coming out of Vermont. To help with recovery, Vermont released 29 eagles between 2004 and 2006. But while bald eagle populations are soaring throughout North America, it wasn’t until 2008 that the first breeding pair was confirmed in Vermont – the last state to have breeding eagles confirmed. By last year, there were 44 breeding pairs in the state. The Wildlife Society reports that in February 2022, Vermont officially removed bald eagles from its list of threatened and endangered species.

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While eagles recovered from the major population crash they experienced in the mid-1900s, there is still some reason to be concerned about impacts to their populations and there is an important role for hunters to continue to play in their conservation.

Concern for Eagles

David Frey at The Wildlife Society has done a great job tracking the emerging science around lead contamination in eagles. In an article released on February 17, he reviews two recent scientific papers: one published in January in The Journal of Wildlife Management and the other published in February in the journal Science. Both papers documented impacts to bald and golden eagle (Aquila chrysaetos) populations from lead contamination.

I mentioned that there are an estimated 316,700 bald eagles. Golden eagle numbers are still far lower, estimated at only 30,000. The two studies looked at the effects of lead contamination, which for hunters, should concern us because the primary source of lead exposure for eagles is scavenging at gut piles left by hunters.

golden eagle
Photo by Pixabay on

The first study looked at data on bald eagles between 1990 and 2018 in seven eastern United States specifically and estimated that in that region, lead contamination has caused a decline population growth between 4.2 and 6.3%. The study also found declines in resilience in hatchling and breeding females – meaning that they are less able to recover from the impacts of lead.

The other study examined the issue across 38 States and found both chronic lead poisoning in around 46% of bald and golden eagles and acute lead poisoning in around 30% of eagles. The research found that the levels of lead poisoning are causing bald eagle population growth to slow by 3.8% and golden eagle population growth to slow by 0.8% – and remember that golden eagle populations are already substantially lower.

Ballistics and Effectiveness

What this points to is that lead ammunition continues to negatively impact wildlife. Scientific research and hunting organizations such as Sporting Lead-Free advocate for switching to lead-free ammunition for human health reasons, such as reducing lead exposure when we eat game meat we shot with lead. But these studies also continue to reinforce the wider ecosystem impacts of lead ammunition.

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Many hunters have already made the switch to lead-free ammunition. Every single big game animal I have shot with a rifle has been with copper bullets and I now spring the extra cash for lead-free shot, including non-waterfowl species.

The science is out there on effectiveness and ballistics.

A 2014 study published in PLOS One comparing the performance of lead-free and lead-containing bullets concluded that in their experiments, “deforming lead-free bullet closely resembled the deforming lead-containing bullet in terms of energy conversion, deflection angle, cavity shape, and reproducibility, showing that similar terminal ballistic behavior can be achieved.”

What about shotgun ammo? Another 2014 study – and bear in mind that the technology has improved since then and continues to improve – published in the Wildlife Society Bulletin compared lead and steel shot loads in mourning dove hunting scenarios. The researchers basically Pepsi-challenged hunters with lead and lead-free ammo, giving hunters different types of ammo and not telling them which they had. That study found that hunters were unable to distinguish the ammunition they were using, that there was no difference in the number of attempts or number of shots fired, no relationship between ammunition type and hunter satisfaction. Importantly, there was also no difference in the number of birds bagged, wounded, or the penetration of the shot.

“This is Now a Socio-Political Issue”

Beyond the pure science, issues around lead contamination will continue to come up in politics.

In November 2021, the Center for Biological Diversity launched a lawsuit to remove hunting and fishing opportunities from national wildlife refuges across the U.S. In their press release, the Center for Biological Diversity cites the Fish and Wildlife Service’s 2016 order to phase out the use of lead on all national wildlife refuges by 2023. Unfortunately, the Trump administration rescinded the order and the impacts of lead contamination are an impetus for the current lawsuit.

And yet, some hunting and shooting advocacy organizations continue to bury their head in the sand, at best, and worsen the situation with deliberate misinformation, at worst. The Institute for Legislative Action (NRA-ILA), the lobbying arm of the National Rifle Association, ridiculously asserts on its website that “Traditional ammunition does not and has not negatively impacted wildlife populations in North America.” Let’s be unequivocal here: this is blatantly false and the NRA-ILA is completely wrong. And they are actively harming the image of hunting and shooting and the future of healthy wildlife by continuing to propagate this falsehood.

The cycle of lead from spent ammunition. Lead from gunshot or bullets will enter the food chain and expose humans and animals to health risks (Arnemo et al., 2016). Illustration created by Diogo Guerra (© Diogo Guerra)

A review of peer-reviewed scientific papers published in 2016 in the journal EcoHealth examined the state of knowledge of the impacts of lead on wildlife, the environment, and human health. The authors found that out of the 570 papers they reviewed, “more than 99% of them raised concerns over use of lead-based ammunition.” The review notes that according to the World Health Organization (WHO), there is no safe level of lead intake for humans – all lead intake is bad. The authors poignantly point out that we have the knowledge; our understanding of the harmful impacts of lead will not change with more science. Instead, we need policies and other regulatory initiatives. “This is now a socio-political issue,” the paper concludes.

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Hunters are some of the most vocal advocates for conservation ethics and science-based management. We point out that when history called for difficult decisions, such as reducing hunting, implementing levies and taxes to generate revenue for conservation, or working with non-hunters to enact legislation to protect declining species, we were there and embraced these difficult tasks. Hunters continue to call on anti-hunting organizations to recognize the rigor of modern hunting regulations and practices and to respect scientific studies that indicate hunting is sustainable. We need to apply this call for science-based decision-making to our own choices.

The science is clear: lead ammunition is bad for humans, environments, and wildlife. Lead-free ammunition is effective for hunting.

Organizations like the Center for Biological Diversity will very likely continue to find reasons to try to curtail hunting opportunities. However, we should also look for ways to proactively undermine these efforts and advocate for progressive policies that emphasize how hunters prioritize environmental stewardship – and perhaps more importantly, I think we have a moral obligation to to make choices that protect the health of wildlife and landscapes.

Hunting organizations should get ahead of these issues and be the advocates for lead-free hunting and fishing options.

2 Comments on “The Science and Impacts of Lead Ammunition

  1. I like your comments and concur that we cannot advocate for the science on one hand and ignore it on the other when it doesn’t suit. I will be making the switch to lead free bullets.

    On a slightly different but similar note, the science tells us that baiting deer adds to the risk of spreading CWD which could become one of the biggest threats to hunting. Perhaps you could share your thoughts on this issue?

  2. Pingback: Frontline Dispatches – April 2022 Vol. IV, No. 4 - Conservation Frontlines

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