Health effects following chronic dosing with tungsten-iron and tungsten-polymer shot in adult game-farm mallards

Permanent approval of shot composed of tungsten-iron and tungsten-polymer f or waterfowl hunting by the U.S. Fish and Wildlife Service was pending the results of the present study that examined the health and reproductive effe cts of the two shot types on mallards (Anas platyrhynchos) over a 150-day p eriod. We collected data pertaining to the effects of tungsten-iron and tun gsten-polymer shot on mortality body weight, organ weight, tissue pathology , and shot erosion. Thirty-two bird groups (sexes equal) of adult mallards were dosed orally with eight #4 steel shot (control), eight #4 tungsten-iro n shot, or eight #4 tungsten-polymer shot on days 0, 30, 60, 90, and 120 of a 150-day trial (26 January 1998 to 25 June 1998). An additional 12 mallar ds (sexes equal) were dosed orally with eight #4 lead shot (positive contro l) on day 0 of the study. All lead-dosed ducks died by day 25, whereas no d ucks died in the other treatment groups. Significant liver hemosiderosis wa s present in all control and tungsten-iron-dosed males, in five of eight co ntrol and three of eight tungsten-iron-dosed females, and in one tungsten-p olymer-dosed male examined. The rate of shot erosion was highest for tungst en-polymer shot (99%), followed by tungsten-iron (72%), and steel (55%) sho t. Tungsten-iron or tungsten-polymer shot repeatedly administered to adult mallards did not have deleterious health effects during the 150-day trial b ased on mortality, body weights, organ weights, and histology of the liver and kidneys.