Heavy metals in tissues of the mute Swan (Cygnus olor).

During the period 1973–1977, a number of mute swans (Cygnus olor) were submitted to the National Veterinary Institute in Stockholm and examined post mortem. Organ tissues from 58 swans were chemically analysed for concentrations of lead, cadmium, copper, zinc, iron and manganese. In 10 swans (17 %), elevated residues of lead were found indicating intoxication. Cadmium concentrations were significantly higher in adult than in juvenile swans; also in swans from the Swedish east coast compared with specimens from the west coast. Remarkably high copper concentrations were often found, with one exception yet without any signs of intoxication. High zinc and cadmium concentrations were often found in the same swans. The findings of iron and manganese were not remarkable.