title: Toxic exposure of songbirds to lead in the Southeast Missouri Lead Mining District.
abstract: Mining and smelting in the Southeast Missouri Lead Mining District has caused widespread contamination of soils with lead (Pb) and other metals. Soils from three study sites sampled in the district contained from approximately 1,000-3,200 mg Pb/kg. Analyses of earthworms [33-4,600 mg Pb/kg dry weight (dw)] collected in the district showed likely high Pb exposure of songbirds preying on soil organisms. Mean tissue Pb concentrations in songbirds collected from the contaminated sites were greater (p < 0.05) than those in songbirds from reference sites by factors of 8 in blood, 13 in liver, and 23 in kidney. Ranges of Pb concentrations in livers (mg Pb/kg dw) were as follows: northern cardinal (Cardinalis cardinalis) = 0.11-3.0 (reference) and 1.3-30 (contaminated) and American robin (Turdus migratorius) = 0.43-8.5 (reference) and 7.6-72 (contaminated). Of 34 adult and juvenile songbirds collected from contaminated sites, 11 (32%) had hepatic Pb concentrations that were consistent with adverse physiological effects, 3 (9%) with systemic toxic effects, and 4 (12%) with life-threatening toxic effects. Acid-fast renal intranuclear inclusion bodies, which are indicative of Pb poisoning, were detected in kidneys of two robins that had the greatest renal Pb concentrations (952 and 1,030 mg/kg dw). Mean activity of the enzyme delta-aminolevulinic acid dehydratase (ALAD) in red blood cells, a well-established bioindicator of Pb poisoning in birds, was decreased by 58-82% in songbirds from the mining sites. We conclude that habitats within the mining district with soil Pb concentrations of ≥1,000 mg Pb/kg are contaminated to the extent that they are exposing ground-feeding songbirds to toxic concentrations of Pb.
authors.affiliation: United States Geological Survey, Patuxent Wildlife Research Center, BARC-East, Building 308, 10300 Baltimore Avenue, Beltsville, MD 20705, USA. nbeyer@usgs.gov
authors.forename: W Nelson
authors.initials: WN
authors.lastname: Beyer
authors.forename: J Christian
authors.initials: JC
authors.lastname: Franson
authors.forename: John B
authors.initials: JB
authors.lastname: French
authors.forename: Thomas
authors.initials: T
authors.lastname: May
authors.forename: Barnett A
authors.initials: BA
authors.lastname: Rattner
authors.forename: Valerie I
authors.initials: VI
authors.lastname: Shearn-Bochsler
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Warner
authors.forename: John
authors.initials: J
authors.lastname: Weber
authors.forename: David
authors.initials: D
authors.lastname: Mosby
mesh_terms: D000818:Animals; D004781:Environmental Exposure; D004784:Environmental Monitoring; D007854:Lead / Q000032:analysis / Q000097:blood / Q000633:toxicity*; D013058:Mass Spectrometry; D019216:Metals, Heavy / Q000032:analysis / Q000097:blood / Q000633:toxicity; D008906:Mining; D008923:Missouri; D009835:Oligochaeta / Q000378:metabolism*; D012989:Soil Pollutants / Q000032:analysis / Q000097:blood / Q000633:toxicity*; D020308:Songbirds / Q000378:metabolism*
chemical_list: D019216:Metals, Heavy; D012989:Soil Pollutants; D007854:Lead