The use of bismuth bullets – an alternative to lead shots, which were banned in the 1990s for environmental reasons – has raised concerns among some U of T researchers that the substance may be entering the food chain.
“It’s not clear whether bismuth is non-toxic,” says William Gough, a professor of environmental sciences at U of T at Scarborough and co-author of a study on bismuth published in Environmental Pollution. “Our final recommendation is to abandon bismuth and use steel shots until further research is completed.”
Gough, graduate student Ruwan Jayasinghe and colleagues at McMaster, Queen’s and the University of Waterloo examined the muscle and liver tissues of mallard ducks, northern pintails, green-winged teals, Canada geese and snow geese and found evidence of lead contamination resulting from bismuth use. The waterfowl samples were all provided by hunters from First Nations Cree communities, who eat the birds as part of their traditional diet. Researchers also believe there are errors in the original studies that justified the switch to bismuth.
Human and laboratory animal studies have suggested that excessive bismuth exposure may be linked to blood, liver, kidney and neural problems.