Abstract
Particles of white phosphorus (P~4~) in pond sediments at Eagle River Flats, Alaska, USA, a military artillery range are acutely toxic to dabbling ducks and swans. We determined if toxicity of P~4~ to ducks varied by its form (i.e., dissolved or particulate) or particulate size. Residual P~4~ in the digestive tracts of ducks was measured to assess risks posed to predators and scavengers of ducks. Farm‐reared mallards were treated with 12 mg P~4~/kg body weight, either dissolved in oil, or as numerous small, or one to two large particles. At the first major convulsion, ducks were euthanized and the quantity and location of P~4~ in the digestive tract were determined. These data were compared to data from dead ducks collected from the artillery range. Dissolved, small, or large particles of P~4~ produced similar acute toxicity. Residual P~4~ in digestive tracts was greatest in ducks treated with small particles and was as great as 3.5 mg P~4~. Similar quantities of residual P~4~ were found in dead ducks collected at Eagle River Flats. For dabbling ducks, P~4~ particle size is not as important as the dose ingested. For predators, the P~4~ contents of the entire digestive tract is important for assessment of the risk of poisoning.