Toxicity of Anacostia River, Washington, DC, USA, sediment fed to mute swans (Cygnus olor)

Sediment ingestion is Sometimes the principal route by which waterfowl are exposed to environmental contaminants, and at severely contaminated sites w aterfowl have been killed by ingesting sediment. Mute swans (Cygnus olor) w ere fed a diet for 6 weeks with a high but environmentally realistic concen tration (24%) of sediment from the moderately polluted Anacostia River in t he District of Columbia, USA, to estimate the sediment's toxicity. Control swans were fed the same diet without the sediment. Five organochlorine comp ounds were detected in the treated diets, bur none of 22 organochlorine com pounds included in the analyses was detected in livers of the treated swans . The concentrations of 24 polynuclear aromatic hydrocarbons measured in th e treated diet were as high as 0.80 mg/kg, and they were thought to have be en responsible for the observed induction of hepatic microsomal monooxygena se activity in livers. A concentration of 85 mg/kg of lead in the diet was enough to decrease red blood cell ALAD activity but was not high enough to cause more serious effects of lead poisoning. The dietary concentrations of Al, Fr, V, and Ba were high compared to the concentrations of these elemen ts known to be toxic in laboratory feeding studies. However, the lack of ac cumulation in the livers of the treated swans suggested that these elements were not readily available from the ingested sediment. We did not study al l potential toxic effects, bur, on the basis of those that we did consider, we concluded that the treated swans were basically healthy after a chronic exposure to the sediment.