The last factory producing lead bullets in the United States will close its doors on 31 December on the orders of the federal Environmental Protection Agency (EPA), which says lead bullets are "harmful to wildlife" - presumably unlike the "green" copper bullets which will replace them.

The closure of the Doe Run company's lead smelter in Herculaneum, MIssouri, marks the end for the lead bullet, a victim of environmental and marketing forces. In 2010 Doe Run settled a $65 million deal with the EPA and Missouri State regulators in the hope it would be able to continue manufacturing other lead products, but a change in federal regulations in 2012 meant it had to abandon its plans and on 31 December 145 Doe Run employees will lose their jobs.

The switch to "greener" copper bullets has been criticised by the gun lobby. In a statement the National Rifle Association (NRA) said:

"Whatever the EPA's motivation when creating the new lead air quality standard, increasingly restrictive regulation of lead is likely to affect the production and cost of traditional ammunition."

The military have already announced they won't use lead bullets after 2018 and the State of California has announced that lead bullets must be phased out of hunting by 2019.

When that announcement was made by Governor Jerry Brown the Center for Biological Diversity said in a statement: "California has taken a historic step to protect its wildlife from lead poisoning. Switching to nontoxic ammunition will save the lives of eagles, condors and thousands of other birds every year – and, importantly, will keep hunters and their families from being exposed to toxic lead. It's great to see California lead the nation in getting lead out of the wild."

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However in a country where mass shootings are an all-too-common occurrence and which averages 87 gun-related gun deaths every day, the switch from lead to copper won't be much consolation for the country's many anti-gun campaigners.