Lead shot is still widely used in bird hunting, although it has been banned in some countries. It is documented that whole shot pellets eaten occasionally may result in increased lead exposure and intoxication in humans. However, not only whole pellets will remain in tissue from species killed by lead shot. High lead concentrations have been attributed to the presence of lead fragments 1-2 millimeters (mm) in length to very fine dust and were judged to be the result of the disruption of lead shot pellets upon collision with bone. Thus tissue may become contaminated with high concentrations of lead through this mechanism as found in Canada and Greenland. This means that lead shot contamination of birds may a significant source of lead in the diet of people exposed. In some cases safe limits of human lead intake will be largely exceeded. As illustrated in the figure, a single bird meal of eider may result in a lead intake close to the tolerable weekly intake.
In a study of the relationship between the intake of birds hunted with lead shot and the lead concentration in human blood among hunters in Greenland, we found a clear relationship between the number of bird meals and blood lead and also a clear seasonal variation. The concentration was highest in mid winter when bird consumption is at its highest. Blood lead was low (15 micrograms per liter [µg/L], mean concentration) among the participants reporting not eating birds. Among those reporting to eat birds regularly, blood lead was significantly higher, up to 128 µg/L (mean concentration). Concentrations depended on the frequency of bird meals: the more bird meals, the higher resulting blood lead. This clear relationship points to lead shot as the dominating lead source to people in Greenland.
- Johansen, P., Pedersen, H.S., Asmund, G. & Riget, F.F. 2006. Lead shot from hunting as a source of lead in human blood. Environmental Pollution, 142(1):93-97.
- Johansen, P., Asmund, G. & Riget, F.F. 2004. High human exposure to lead through consumption of birds hunted with lead shot. Environmental Pollution, 127(1):125-129.
- Bjerregaard, P., Johansen, P., Mulvad, G., Pedersen, H.S. & Hansen, J.C. 2004. Lead sources in human diet in Greenland. Environmental Health Perspectives, 112(15):1496-1498.