title: Relative importance of direct and trophic uranium exposures in the crayfish Orconectes limosus: Implication for predicting uranium bioaccumulation and its associated toxicity.
abstract: Pollutants that occur at sublethal concentrations in the environment may lead to chronic exposure in aquatic organisms. If these pollutants bioaccumulate, then organisms higher in the food chain may also be at risk. Increased attention has thus been focused on the relative importance of dietary uptake, but additional knowledge of the cellular distribution of metals after dietary exposure is required to assess the potential toxicity. The authors address concerns relating to increasing uranium (U) concentrations (from 12 µg/L to 2 mg/L) in the freshwater ecosystem caused by anthropogenic activities. The objective of the present study is to compare uranium bioaccumulation levels in tissues and in the subcellular environment. The authors focused on the cytosol fraction and its microlocalization (TEM-EDX) in the gills and the hepatopancreas (HP) of the crayfish Orconectes limosus after 10 d of direct exposure (at concentrations of 20, 100, and 500 µg/L) and five trophic exposure treatments (at concentrations from 1 to 20 µg/g). Results indicated that adsorption of uranium on the cuticle represents the main contribution of total uranium accumulation to the animal. Accumulation in the gills should be considered only as a marker of waterborne uranium exposure. Accumulation in the HP after trophic environmental exposure conditions was higher (18.9 ± 3.8 µg/g) than after direct exposure. Moreover, no significant difference in the subcellular distribution of uranium (50%) in HP was observed between animals that had been exposed to both types of treatment. A potential toxic effect after uranium accumulation could therefore exist after trophic exposure. This confirms the need to focus further studies on the metal (uranium) risk assessment.
authors.affiliation: Laboratoire de Radioécologie et d'Ecotoxicologie, Institut de Radioprotection et de Sûreté Nucléaire, Saint Paul Lez Durance, France. olivier.simon@irsn.fr
authors.forename: Olivier
authors.initials: O
authors.lastname: Simon
authors.forename: Magali
authors.initials: M
authors.lastname: Floriani
authors.forename: Virginie
authors.initials: V
authors.lastname: Camilleri
authors.forename: Rodolphe
authors.initials: R
authors.lastname: Gilbin
authors.forename: Sandrine
authors.initials: S
authors.lastname: Frelon
mesh_terms: D000818:Animals; D059001:Aquatic Organisms; D003400:Astacoidea / Q000378:metabolism*; D017753:Ecosystem; D004781:Environmental Exposure / Q000032:analysis* / Q000706:statistics & numerical data; D020387:Food Chain; D005618:Fresh Water / Q000737:chemistry; D005880:Gills / Q000378:metabolism; D043143:Hepatopancreas / Q000378:metabolism; D018570:Risk Assessment; D014501:Uranium / Q000378:metabolism* / Q000633:toxicity; D014875:Water Pollutants, Radioactive / Q000378:metabolism* / Q000633:toxicity; D014878:Water Pollution, Radioactive / Q000706:statistics & numerical data
chemical_list: D014875:Water Pollutants, Radioactive; D014501:Uranium