Lead is a highly toxic poison affecting almost all systems of the body. Wildlife is exposed to lead via sources such as fishing weights, leaded paint, mining and smelting activities, but by far the greatest exposure comes from spent ammunition, mainly spent gunshot. Waterfowl and terrestrial game birds mistakenly ingest spent cartridge shot in place of the grit needed to aid digestion of food within their muscular gizzard.
The disease negatively affects many body systems and is an important cause of mortality e.g. it has been estimated that 8.7% of the population of 17 species of wildfowl in Europe might die each year from lead poisoning during the winter season (November to February). Recent WWT research found a third of tested waterbirds had lead levels in their blood indicative of lead poisoning. Additionally, the disease was responsible for the deaths of 1 in 10 birds found dead over the last four decades, with no measurable changes following introduction of legislation.
WWT has monitored the disease and its impacts for decades and been instrumental in pushing for national and international legislative changes to reduce risks to wildlife from lead. The UK is now committed under the African-Eurasian Waterbird Agreement (AEWA) to phasing out the use of lead shot over wetlands, with regulations restricting the use of lead shot being introduced in England, Wales, Scotland and Northern Ireland in 1999, 2002, 2004 and 2009, respectively.
Do birds die from eating lead shot?
This video explains how lead is ingested by waterbirds. We filmed this during one of the many post mortems carried out by WWT on waterbirds over the past few decades.
Measuring whether the law works
So, does the law in England work? A small WWT study conducted with RSPB during 2001/2002 found that compliance with the law in England was very poor with 69% of birds from a game dealer survey having been shot illegally with lead. More recently, in 2008, Defra commissioned WWT, working with the British Association for Shooting and Conservation (BASC), to conduct a larger scale 18 month study to assess compliance with these regulations.
The same high level of non-compliance was found across two winters (2008/09 and 2009/10) and across the country.
Why is compliance with the law so low? Questionnaire surveys of the shooting community (BASC members and shoot providers) found a good understanding of the spirit of the law, however, 45% indicated that they sometimes or never comply with the regulations. Reasons for non-compliance included disagreement with the reasons for the regulations with a widely held belief that lead poisoning was not a sufficiently great problem, perceptions about the cost and efficacy of alternatives to lead shot, and also the lack of enforcement.
The findings of the report are being considered by Defra and the Lead Ammunition Group.
Impacts on human health
There has been mounting concern about the potential impacts of lead ammunition on human health with evidence showing that lead bullets and gunshot fragment on impact, leaving small lead particles distributed throughout game tissue destined for consumption. Given WWT’s duty of care to better understand the risks that lead ammunition may pose to human health as well as wetland wildlife as it advises communities on the sustainable use and management of wetland resources in the UK and overseas, WWT conducted a study to investigate the levels of lead to which consumers of game in UK are exposed.
The results were worrying. A high proportion of samples had lead concentrations above the European Union Maximum Level for domestic animal meat (no level is set for game meat). Overall, these and others' findings have indicated that the potential risk to human health from lead ingested through eating wild game is greater than previously thought, especially for vulnerable groups such as children, pregnant women and those trying to get pregnant, and for those eating large amounts of game meat.
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