title: Tissue-based risk assessment of great blue heron (Ardea herodias) exposed to PCDD/DF in the Tittabawassee River floodplain, Michigan, USA.
abstract: Concentrations of dioxin-like compounds, primarily polychlorinated dibenzofurans (PCDFs), in soils and sediments of the Tittabawassee River (TR) and associated floodplains downstream of Midland, Michigan, USA, were greater than upstream sites and prompted a site-specific risk assessment of great blue herons (GBH). Tissue exposure of PCDF and polychlorinated dibenzo-p-dioxins (PCDDs) was assessed in multiple GBH tissue types, including blood plasma of adults and eggs, as well as blood plasma, adipose, liver, and muscle of nestlings. Adult GBH exposure was associated with foraging area and age class, with concentrations of PCDD/DF being greater in blood plasma of adult GBH foraging in the TR compared with those foraging in upstream reference areas and in older birds as compared with their younger cohorts. Concentrations of PCDD/DFs and dioxin-like polychlorinated biphenyls (PCBs) in eggs and nestling tissues of GBH collected from rookeries within the TR floodplain were generally similar among rookeries. Mean concentrations of PCDD/DFs in eggs of GBH ranged from 45 to 67 ng/kg, wet weight for the rookeries studied, with a maximum concentration of 210 ng/kg, wet weight observed. Adipose consistently had the greatest concentration of PCDD/DFs of all tissues collected from nestlings of GBH, ranging from 98 to 430 ng/kg, wet weight. Potential for adverse population-level effects from site-specific contaminant exposures were evaluated by comparison with selected toxicity reference values (TRVs). Minimal risk of adverse population-level effects were predicted when exposures measured in tissues of GBH collected from rookeries within the TR were compared with appropriate TRVs. This prediction is consistent with site-specific measures of population condition, which included clutch size and number of nestlings per successful nest.
authors.affiliation: Department of Zoology, Center for Integrative Toxicology, Michigan State University, East Lansing, Michigan 48824, USA. sestonri@msu.edu
authors.forename: Rita M
authors.initials: RM
authors.lastname: Seston
authors.forename: Timothy B
authors.initials: TB
authors.lastname: Fredricks
authors.forename: Dustin L
authors.initials: DL
authors.lastname: Tazelaar
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Coefield
authors.forename: Patrick W
authors.initials: PW
authors.lastname: Bradley
authors.forename: John L
authors.initials: JL
authors.lastname: Newsted
authors.forename: Denise P
authors.initials: DP
authors.lastname: Kay
authors.forename: Scott D
authors.initials: SD
authors.lastname: Fitzgerald
authors.forename: John P
authors.initials: JP
authors.lastname: Giesy
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Zwiernik
mesh_terms: D000273:Adipose Tissue / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D001717:Birds; D004305:Dose-Response Relationship, Drug; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008824:Michigan; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism*; D010063:Ovum / Q000378:metabolism; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000032:analysis / Q000633:toxicity; D018570:Risk Assessment; D045483:Rivers / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000633:toxicity
chemical_list: D000072317:Polychlorinated Dibenzodioxins; D014874:Water Pollutants, Chemical