title: Great horned owl (Bubo virginianus) dietary exposure to PCDD/DF in the Tittabawassee River floodplain in Midland, Michigan, USA.
abstract: Soils and sediments in the floodplain of the Tittabawassee River downstream of Midland, Michigan, USA contain elevated concentrations of polychlorinated dibenzofurans (PCDF) and polychlorinated dibenzo-p-dioxins (PCDD). As a long-lived, resident top predator, the great horned owl (Bubo virginianus; GHO) has the potential to be exposed to bioaccumulative compounds such as PCDD/DF. Site-specific components of the GHO diet were collected along 115 km of the Tittabawassee, Pine, Chippewa, and Saginaw Rivers during 2005 and 2006. The site-specific GHO biomass-based diet was dominated by cottontail rabbits (Sylvilagus floridanus) and muskrats (Ondatra zibethicus). Incidental soil ingestion and cottontail rabbits were the primary contributors of PCDD/DF to the GHO diet. The great horned owl daily dietary exposure estimates were greater in the study area (SA) (3.3 to 5.0 ng 2,3,7,8-TCDD equivalents (TEQ(WHO-avian))/kg body wt/d) than the reference area (RA) (0.07 ng TEQ(WHO-Avian)/kg body wt/d). Hazard quotients (HQs) based on central tendency estimates of the average daily dose and no-observable-adverse effect level (NOAEL) for the screech owl and uncertainty factors were <1.0 for both the RA and the SA. Hazard quotients based on upper end estimates of the average daily dose and NOAEL were <1.0 in the RA and up to 3.4 in the SA.
authors.affiliation: Zoology Department, Center for Integrative Toxicology, Michigan State University, East Lansing, Michigan 48824, USA.
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Coefield
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Zwiernik
authors.forename: Timothy B
authors.initials: TB
authors.lastname: Fredricks
authors.forename: Rita M
authors.initials: RM
authors.lastname: Seston
authors.forename: Michael W
authors.initials: MW
authors.lastname: Nadeau
authors.forename: Dustin L
authors.initials: DL
authors.lastname: Tazelaar
authors.forename: Jeremy N
authors.initials: JN
authors.lastname: Moore
authors.forename: Denise P
authors.initials: DP
authors.lastname: Kay
authors.forename: Shaun A
authors.initials: SA
authors.lastname: Roark
authors.forename: John P
authors.initials: JP
authors.lastname: Giesy
mesh_terms: D000818:Animals; D001572:Benzofurans / Q000633:toxicity*; D000072338:Dibenzofurans, Polychlorinated; D004032:Diet; D004781:Environmental Exposure; D008824:Michigan; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000633:toxicity; D020305:Strigiformes
chemical_list: D001572:Benzofurans; D000072338:Dibenzofurans, Polychlorinated; D000072317:Polychlorinated Dibenzodioxins