title: Acute and chronic toxicity of lead in water and diet to the amphipod Hyalella azteca.
abstract: We evaluated the influence of waterborne and dietary lead (Pb) exposure on the acute and chronic toxicity of Pb to the amphipod Hyalella azteca. Test solutions were generated by a modified diluter with an extended (24-h) equilibration period. Acute (96-h) toxicity of Pb varied with water hardness in the range of 71 to 275 mg/L as CaCO3, despite similar dissolved Pb concentrations. Acute toxicity was greatest in soft test water, with less than 50% survival at the lowest dissolved Pb concentration (151 microg/L). Survival also was significantly reduced in medium-hardness water but not in hard test water. In chronic (42-d) studies, amphipods were exposed to waterborne Pb and fed either a control diet or a diet equilibrated with waterborne Pb levels. For animals fed the control diet, the median lethal concentration (LC50) for Pb was 24 degrees g/L (as dissolved Pb), and significant reductions in survival occurred at 16 microg/L. Exposure to Pb-treated diets significantly increased toxicity across a wide range of dissolved Pb concentrations, with a LC50 of 16 microg/L and significant reductions in growth and reproduction at 3.5 microg/L. Significant effects on growth and reproduction occurred at dissolved Pb concentrations close to the current U.S. chronic water-quality criterion. Our results suggest that both aqueous- and dietary-exposure pathways contribute significantly to chronic Pb exposure and toxic effects in aquatic biota.
authors.affiliation: US Geological Survey, Columbia Environmental Research Center, 4200 New Haven Road, Columbia, Missouri 65201, USA. jbesser@usgs.gov
authors.forename: John M
authors.initials: JM
authors.lastname: Besser
authors.forename: William G
authors.initials: WG
authors.lastname: Brumbaugh
authors.forename: Eric L
authors.initials: EL
authors.lastname: Brunson
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Ingersoll
mesh_terms: D033304:Amphipoda / Q000187:drug effects*; D000818:Animals; D004032:Diet; D007854:Lead / Q000008:administration & dosage / Q000633:toxicity*; D018675:Toxicity Tests; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; D007854:Lead