Multiple lines of evidence risk assessment of American robins exposed to polychlorinated dibenzofurans (PCDFS) and polychlorinated dibenzo-P-dioxins (PCDDS) in the Tittabawassee River floodplain, Midland, Michigan, USA.

Concentrations of polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo-p-dioxins (PCDDs) in Tittabawassee River floodplain soils and biota downstream of Midland, Michigan, USA, are greater than regional background concentrations. From 2005 to 2008, a multiple lines of evidence approach was utilized to evaluate the potential for effects of PCDD/DFs on American robins (Turdus migratorius) breeding in the floodplains. A dietary-based assessment indicated there was potential for adverse effects for American robins predicted to have the greatest exposures.

Reproductive success of three passerine species exposed to dioxin-like compounds near Midland, Michigan, USA.

Nests of three passerine birds, house wren (HOWR), tree swallow (TRES), and eastern bluebird (EABL) were monitored daily (2005-2007) at study areas (SAs) downstream of Midland, Michigan where soil and sediment concentrations of polychlorinated dibenzofurans (PCDFs) were significantly greater than the regional background concentrations and upstream reference areas (RAs). Similarly, TRES research conducted at sites contaminated with dioxin-like compounds indicated that concentrations of polychlorinated dibenzo-p-dioxins and PCDFs, expressed as ΣPCDD/DFs and 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents observed in the diet and eggs of these three species would be predicted to cause significant effects on reproduction. However, site-specific reproductive parameters including hatching success and fledging success at downstream SAs were similar to or greater than those at upstream RAs.

Dietary- and tissue-based exposure of belted kingfisher to PCDFs and PCDDs in the Tittabawassee River floodplain, Midland, MI, USA.

Concentrations of polychlorinated dibenzofurans (PCDFs) and other dioxin-like compounds in soils and sediments of the Tittabawassee River and associated floodplains downstream of Midland, Michigan, USA, are greater than upstream sites. As a result of these concentrations, which are some of the greatest ever reported, a site-specific exposure assessment of belted kingfisher breeding in the assessment area was conducted. To reduce the uncertainty associated with predicting exposure from abiotic matrices, concentrations of residues were quantified in site-specific prey items and in eggs and nestlings of belted kingfisher.

Multiple Lines of Evidence Risk Assessment of Terrestrial Passerines Exposed to PCDFs and PCDDs in the Tittabawassee River Floodplain, Midland, Michigan, USA.

A site-specific multiple lines of evidence risk assessment was conducted for house wrens (Troglodytes aedon) and eastern bluebirds (Sialia sialis) along the Tittabawassee River downstream of Midland, Michigan, where concentrations of polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo-p-dioxins (PCDDs) in flood-plain soils and sediments are greater compared to upstream areas and some of the greatest anywhere in the world. Lines of evidence supporting the population-level assessment endpoints included site-specific dietary- and tissue-based exposure assessments and population productivity measurements during breeding seasons 2005-2007. While a hazard assessment based on site-specific diets suggested that populations residing in the downstream floodplain had the potential to be affected, concentrations in eggs compared to appropriate toxicity reference values (TRVs) did not predict a potential for population-level effects.

Effects on tree swallows exposed to dioxin-like compounds associated with the Tittabawassee River and floodplain near Midland, Michigan, USA.

Concentrations of dioxin-like compounds, primarily polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo-p-dioxins (PCDDs), in soils and sediments downstream of Midland, Michigan (USA) were greater than upstream sites and prompted a site-specific hazard assessment of tree swallows breeding in the associated floodplains. Potential for adverse population-level effects from site-specific contaminant exposures were evaluated at study areas (SAs) along the Tittabawassee and Saginaw rivers downstream of Midland. The site-specific multiple lines of evidence approach to hazard assessment included endpoints for dietary- and tissue-based exposures, and population productivity measurements for tree swallows ([TS]; Tachycineta bicolor) measured during the 2005, 2006, and 2007 breeding seasons.

Dietary exposure of great blue heron (Ardea herodias) to PCDD/DFs in the Tittabawassee River floodplain, MI, USA.

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). Dietary exposure of GBH to PCDFs and polychlorinated dibenzo-p-dioxins (PCDDs) was evaluated based on site-specific concentrations of residues in prey items. Concentrations of ∑PCDD/DFs and 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQ(WHO-Avian)) in prey items collected from the TR were consistently greater than those collected from associated reference areas (RAs) and further downstream in the Saginaw River (SR).

Tissue-based risk assessment of great blue heron (Ardea herodias) exposed to PCDD/DF in the Tittabawassee River floodplain, Michigan, USA.

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.

Great horned owl (Bubo virginianus) dietary exposure to PCDD/DF in the Tittabawassee River floodplain in Midland, Michigan, USA.

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.

Ecological risk assessment of great horned owls (Bubo virginianus) exposed to PCDD/DF in the Tittabawassee River floodplain in Midland, Michigan, USA.

Soils and sediments downstream of Midland, Michigan, USA have elevated polychlorinated dibenzofuran (PCDF) and polychlorinated dibenzo-p-dioxin (PCDD) concentrations. To determine if the PCDD/DF concentrations have the potential to adversely affect terrestrial avian predators, a site-specific, multiple lines of evidence risk assessment was conducted for the great horned owl (Bubo virginianus; GHO). As long-lived resident top predators, the GHO has the potential to be exposed to relatively great concentrations of bioaccumulative compounds such as PCDD/DF.

Effects of in ovo exposure of white leghorn chicken, common pheasant, and Japanese quail to 2,3,7,8-tetrachlorodibenzo-p-dioxin and two chlorinated dibenzofurans on CYP1A induction.

In birds, activation of the aryl hydrocarbon receptor (AhR) by some polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) results in induction of cytochrome P4501A (CYP1A) expression. This response has been useful for predicting relative sensitivity of birds to dioxin-like compounds. To further investigate species-sensitivity to dioxins and dioxin-like compounds induction of cytochrome P450 1A4 and 1A5 (CYP1A4 and CYP1A5) mRNA and ethoxyresorufin O-deethylase (EROD) activity were quantified in liver of posthatch white leghorn chicken, common pheasant, and Japanese quail exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 2,3,4,7,8-pentachlorodibenzofuran (PeCDF), or 2,3,7,8-tetrachlorodibenzofuran (TCDF) via air cell injection.

Bioaccumulation of polychlorinated dibenzo-p-dioxins, dibenzofurans, and dioxin-like polychlorinated biphenyls in fishes from the Tittabawassee and Saginaw Rivers, Michigan, USA.

Characterizing biological factors associated with species-specific accumulation of contaminants is one of the major focuses in ecotoxicology and environmental chemistry studies. In this study, polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and non- and mono-ortho-substituted polychlorinated biphenyl (PCB) congeners were analyzed in various fish species from the Tittabawassee and Saginaw Rivers (12 fish species; n=314 individuals), Michigan, USA. Due to their migratory habits, greater delta(13)C stable isotope values were found in walleye and white sucker among 12 fish species.

Passerine exposure to primarily PCDFs and PCDDs in the river floodplains near Midland, Michigan, USA.

House wren (Troglodytes aedon), tree swallow (Tachycineta bicolor), and eastern bluebird (Sialia sialis) tissues collected in study areas (SAs) downstream of Midland, Michigan (USA) contained concentrations of polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo-p-dioxins (PCDDs) greater than in upstream reference areas (RAs) in the region. The sum of concentrations of PCDD/DFs (SigmaPCDD/DFs) in eggs of house wrens and eastern bluebirds from SAs were 4- to 22-fold greater compared to those from RAs, whereas concentrations in tree swallow eggs were similar among areas. Mean concentrations of SigmaPCDD/DFs and sum 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (SigmaTEQs(WHO-Avian)), based on 1998 WHO avian toxic equivalency factors, in house wren and eastern bluebird eggs ranged from 860 (430) to 1500 (910) ng/kg wet weight (ww) and 470 (150) to 1100 (510) ng/kg ww, respectively, at the most contaminated study areas along the Tittabawassee River, whereas mean concentrations in tree swallow eggs ranged from 280 (100) to 760 (280) ng/kg ww among all locations.

Hepatic P450 enzyme activity, tissue morphology and histology of mink (Mustela vison) exposed to polychlorinated dibenzofurans.

Dose- and time-dependent effects of environmentally relevant concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQ) of 2,3,7,8-tetrachlorodibenzofuran (TCDF), 2,3,4,7,8-pentachlorodibenzofuran (PeCDF), or a mixture of these two congeners on hepatic P450 enzyme activity and tissue morphology, including jaw histology, of adult ranch mink were determined under controlled conditions. Adult female ranch mink were fed either TCDF (0.98, 3.

Chronic effects of polychlorinated dibenzofurans on mink in laboratory and field environments.

Mink are often used as a sentinel species in ecological risk assessments of chemicals such as polychlorinated biphenyls (PCBs), dibenzo-p-dioxins (PCDDs), and dibenzofurans (PCDFs) that cause toxicity mediated through the aromatic hydrocarbon receptor. Considerable toxicological information is available on the effects of PCBs and PCDDs on mink, but limited toxicological information is available for PCDFs. Thus, exposure concentrations at which adverse effects occur could not be determined reliably for complex mixtures in which PCDFs dominate the total calculated concentration of 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalent (TEQ).

Toxicokinetics of 2,3,7,8-TCDF and 2,3,4,7,8-PeCDF in mink (Mustela vison) at ecologically relevant exposures.

Wild mink (Mustela vison) living along the Tittabawassee River in central Michigan exhibit elevated hepatic and dietary polychlorinated dibenzofuran (PCDF) concentrations exceeding mink-specific, literature-reported toxicity reference values (TRVs) on a toxicity equivalents basis. However, no apparent effects on individuals or population are evident, suggesting that available TRVs may overpredict risk for the site-specific mix of congeners. To investigate this discrepancy, a 180-day spiked feed study was conducted to assess: (1) the dosages of key congeners necessary to achieve liver concentrations bracketing those observed in wild mink, (2) time to achieve steady-state concentrations, and (3) effect of coadministration of 2,3,7,8-tetrachlorodibenzofuran (TCDF) and 2,3,4,7,8-pentachlorodibenzofuran (4-PeCDF) on the toxicokinetics and distribution of each congener.

Exposure and effects assessment of resident mink (Mustela vison) exposed to polychlorinated dibenzofurans and other dioxin-like compounds in the Tittabawassee River basin, Midland, Michigan, USA.

Historically, sediments and floodplain soils of the Tittabawassee River (TR; MI, USA) have been contaminated with polychlorinated dibenzofurans (PCDFs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated biphenyls (PCBs). Median concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQs) based on 2006 World Health Organization tetrachlorodibenzo-p-dioxin toxic equivalency factors (TEFs) in the diet of mink (Mustela vison) ranged from 6.8 x 10(-1) ng TEQ/kg wet weight upstream of the primary source of PCDF to 3.

Risk assessment methodologies for exposure of great horned owls (Bubo virginianus) to PCBs on the Kalamazoo River, Michigan.

Dietary exposures of great horned owls (GHO; Bubo virginianus) to polychlorinated biphenyls (PCBs) in the terrestrial food web at the Kalamazoo River, Michigan, USA, were examined. Average potential daily doses (APDD) in GHO diets were 7- to 10-fold and 3-fold greater at the more contaminated location versus a reference location for site-specific exposures quantified as total PCBs and 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQ(WHO-Avian)), respectively. Wetland/aquatic prey contributed significantly to PCB exposure and APDD.

Nondestructive scat sampling in assessment of mink (Mustela vison) exposed to polychlorinated dibenzofurans (PCDFs).

The mink (Mustela vison) is often utilized as a sentinel species for ecological assessments at sites where contaminants of concern include dioxins and dioxin-like compounds. Utilizing mink scat as a nondestructive tool to determine internal exposure to dioxin-like compounds may allow for rapid, accurate estimates of exposure without the need to capture mink or their prey. To determine the relationships between concentrations of polychlorinated dibenzofurans (PCDFs) in tissues (liver and adipose) and those in scat, mink were fed PCDFs in scat during a controlled laboratory study for 180 days.

Passaic river sediment interstitial water phase I toxicity identification evaluation.

A suite of tests was conducted to evaluate and identify the cause or causes of toxicity in Passaic River sediments. Sediment toxicity was measured with three types of bioassays: a whole sediment bioassay with the marine amphipod, Ampelisca abdita, and interstitial water bioassays with A. abdita and the bioluminescent bacterium Vibrio fisheri (Microtox((R))).

Plasma to egg conversion factor for evaluating polychlorinated biphenyl and DDT exposures in great horned owls and bald eagles.

The benefits of nondestructive sampling techniques, such as plasma sampling, to directly measure contaminant exposure levels in at-risk or protected raptor populations are many. However, such assays are generally inconsistent with the most certain source of toxicity reference values, which are based on feeding studies and quantified as dietary or "in ovo" (egg-based) concentrations. An accurate conversion factor to translate nondestructive plasma-based contaminant concentrations to comparable egg-based concentrations will prove valuable to risk assessors investigating the potential effects of chemical exposures to raptors.

Risk assessment of great horned owls (Bubo virginianus) exposed to polychlorinated biphenyls and DDT along the Kalamazoo River, Michigan, USA.

The great horned owl (GHO; Bubo virginianus) was used in a multiple lines of evidence study of polychlorinated biphenyls (PCBs) and p,p'-dichlorodiphenyltrichloroethane (DDT) exposures at the Kalamazoo River Superfund Site (KRSS), Kalamazoo, Michigan, USA. The study examined risks from total PCBs, including 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQWorld Health Organization [WHO]-Avian Toxicity Equivalency Factor [TEF]), and total DDTs (sum of DDT, dichlorodiphenyldichloroethylene [DDE], and dichlorodiphenyldichloroethane [DDD]; sigmaDDT) by measuring concentrations in eggs and nestling blood plasma in two regions of the KRSS (upper, lower) and an upstream reference area (RA). An ecological risk assessment compared concentrations of the contaminants of concern (COCs) in eggs or plasma to toxicity reference values.

Accumulation of polychlorinated biphenyls from floodplain soils by passerine birds.

Eggs, nestlings, and adults of the eastern bluebird (Sialia sialis) and house wren (Troglodytes aedon) were collected at a polychlorinated biphenyl (PCB)-contaminated site and a reference location on the Kalamazoo River (MI, USA). Eggs and nestlings of eastern bluebirds at the more contaminated location contained concentrations of 8.3 and 1.

Tree swallow (Tachycineta bicolor) exposure to polychlorinated biphenyls at the Kalamazoo River superfund site, Michigan, USA.

In 1990, a portion of the Kalamazoo River in Michigan, USA, was designated a Superfund site because of the presence of polychlorinated biphenyls (PCBs) in the sediment and floodplain soils. During a four-year period from 2000 to 2003, several avian species were monitored for reproductive effects and concentrations of PCBs in tissues attributed to food chain transfer from contaminated sediments. The tree swallow (Tachycineta bicolor) was chosen as a model receptor for contamination of passerine species.

Productivity of tree swallows (Tachycineta bicolor) exposed to PCBs at the Kalamazoo River superfund site.

A 123-km stretch of the Kalamazoo River in Michigan, was designated a Superfund site in 1990 due to historical releases of effluent containing polychlorinated biphenyl (PCB)-contaminated paper waste. Risk to bird species in the river ecosystem was evaluated using the tree swallow (Tachycineta bicolor) as a monitor for possible effects due to PCB exposure at two nesting locations, one in the Superfund site and one in an upstream reference location that is less contaminated with PCBs. In 2 of the 3 years of the study, clutch size at the contaminated location was 3.

Differential accumulation of polychlorinated biphenyl congeners in the aquatic food web at the Kalamazoo River Superfund site, Michigan.

A series of field studies were conducted to gain a better understanding of the bioaccumulation and dynamics of polychlorinated biphenyl (PCB) congeners in the aquatic food web of the Kalamazoo River flood plain. Representative species of passerine birds, mammals, fish, aquatic plants, invertebrates, and colocated sediments were collected from areas located within submerged portions of the former Trowbridge impoundment and also from areas located at an upstream reference location. In most matrixes, total concentrations of PCBs were significantly greater in the downstream study area compared to the upstream reference location.