Hematological effects and metal residue concentrations following chronic dosing with tungsten-iron and tungsten-polymer shot in adult game-farm mallards

The U.S. Fish and Wildlife Service required a chronic dosing study that ass essed the health and reproductive effects of tungsten-iron and tungsten-pol ymer shot in adult game-farm mallards (Anas platyrhynchos) prior to grantin g permanent approval of the shot for waterfowl hunting. Herein, we present the effects of tungsten-iron and tungsten-polymer shot on various hematolog ic parameters and metal residue concentrations in the femur, liver, kidneys , and gonads. Thirty-two-bird groups (sexes equal) of adult mallards were d osed orally with eight #4 steel shot (control), eight #4 tungsten-iron shot , or eight #4 tungsten-polymer shot on days 0, 30, 60, 90, and 120 of 150 d ay trial (26 January 1998 to 25 June 1998). An additional 12 mallards (sexe s equal) received eight #4 lead shot (positive control) on day 0 of the stu dy. Lead-dosed mallards had significantly decreased hematocrit, hemoglobin concentration, and whole-blood delta aminolevulinic acid dehydratase activi ty on day 7, as well as significant changes in a number of plasma chemistry parameters compared to ducks in the control, tungsten-iron, or tungsten-po lymer groups. Mallards dosed with tungsten-iron or tungsten-polymer shot ha d occasional significant differences in hematocrit and plasma chemistry val ues when compared to control mallards over the 150 day period, but these ch anges were not considered to be indicative of deleterious effects. Low conc entrations of tungsten were detected in gonad and kidney samples from males and females and in liver samples from females dosed with tungsten-polymer shot. Tungsten was also detected in femur samples from tungsten-polymer-dos ed mallards. Higher concentrations of tungsten were detected in femur, live r, kidney, and gonad samples from tungsten-iron-dosed ducks. Tungsten-iron or tungsten-polymer shot repeatedly administered to adult mallards did not cause adverse hematological. effects during the 150 day trial. Concentratio ns of tungsten in the femur, liver, kidneys, and gonads were generally high er in tungsten-iron-dosed ducks when compared to tungsten-polymer-dosed duc ks.