Athletes training for Olympic shooting events discharge thousands of rounds of lead ammunition each year, and wildlife and water resources are at risk because of it, according to a team of Canadian researchers calling for a ban of lead ammunition use in Olympic activities.

The 2014 Winter Olympic Games underway in Sochi, Russia this month are not an issue because the lead ammunition from shooting events is collected and recycled, the researchers said. But they contend that recycling practices are not in place during the extensive practice sessions the athletes take place in around the world.

Writing in the journal Environmental Policy and Law, biologist Vernon Thomas of the University of Guelph and David Anderson, former Canadian minister of the environment and former chair of the governing council of the United Nations Environment Program, report that lead poisoning presents risks to wildlife populations and that ecosystems can be damaged by lead contamination.

Lead shot is the only ammunition approved by the International Shooting Sport Federation (ISSF), which regulates Olympic trap and skeet shooting events. As such, lead ammunition is used in Olympic qualifying events and by athletes in practice, the researchers report.

Thomas said that each Olympic shooter discharges more than 1 ton of lead shot each year on practice shooting ranges.

"The real concern is the amount of shot released during the four-year interval by the many hopefuls in each country and the Olympic team members of each country who practice assiduously with over 1,000 shots per week," he said. "This lead shot - many tons - is rarely recovered and poses real toxic risks to wildlife that may ingest it and to groundwater quality."

Steel shot, an alternative to lead ammunition, has been available for about 20 years.

As such, the researchers are calling upon the International Olympic Committee to ban the use of lead ammunition in Olympic events by phasing it out after the 2016 Olympics.

Thomas may get what he's looking for. Earlier research by Thompson outlined lead-free ammunition alternatives for California hunters, which led to a state-wide ban on lead hunting ammunition.