Pesticide and mercury levels in migrating duck populations

In November of 1970 officers of the Iowa State Conservation Commission collected ducks of various species, by shooting, from different locations in the state. Residues of both mercury and chlorinated hydrocarbon insecticides reflect accumulations from their more northern summer environment. Ducks were collected from seven locations and composite samples made of the breast muscle, liver, and fat. Pesticide concentrations are lowest in the breast muscle and highest in the fat for any of the sets of composites. The mercury in the tissues has a distribution distinctly different from the chlorinated hydrocarbons, being lowest in the fat and highest in the liver. Except for two values of mercury in the liver, the samples did not show evidence of significant contamination by pesticides and mercury when evaluated against FDA tolerances for fish. 3 references, 2 tables.