Ecological risk assessment for mink and short-tailed shrew exposed to PCBs, dioxins, and furans in the Housatonic River area.

A probabilistic risk assessment was conducted to characterize risks to a representative piscivorous mammal (mink, Mustela vison) and a representative carnivorous mammal (short-tailed shrew, Blarina brevicauda) exposed to PCBs, dioxins, and furans in the Housatonic River area downstream of the General Electric (GE) facility in Pittsfield, Massachusetts. Contaminant exposure was estimated using a probabilistic total daily intake model and parameterized using life history information of each species and concentrations of PCBs, dioxins, and furans in prey collected in the Housatonic River study area. The effects assessment preferentially relied on dose-response curves but defaulted to benchmarks or other estimates of effect when there were insufficient toxicity data. The risk characterization used a weight of evidence approach. Up to 3 lines of evidence were used to estimate risks to the selected mammal species: 1) probabilistic exposure and effects modeling, 2) field surveys, and 3) species-specific feeding or field studies. The weight of evidence assessment indicated a high risk for mink and an intermediate risk for short-tailed shrew.

Dietary exposure of mink (Mustela vison) to fish from the housatonic river, Berkshire County, Massachusetts, USA: effects on reproduction, kit growth, and survival.

We evaluated the effects of feeding farm-raised mink (Mustela vison) diets containing polychlorinated biphenyl (PCB)-contaminated fish from the Housatonic River (HR; Berkshire County, MA, USA) on adult reproductive performance and kit growth and survival. Diets contained 0.22-3.54% HR fish, providing 0.34-3.7 microg total PCBs (TPCB)/g feed wet wt (3.5-68.5 pg toxic equivalence [TEQ]/g). Female mink were fed diets before breeding through weaning of kits. Twelve kits from each treatment were maintained on their respective diets for an additional 180 d. Dietary PCBs had no effect on the number of offspring produced, gestation period, or other measures of adult reproductive performance. Mink kits exposed to 3.7 microg TPCB/g feed (68.5 pg TEQ/ g) in utero and during lactation had reduced survivability between three and six weeks of age. The lethal concentrations to 10 and 20% of the population (LC10 and LC20, respectively) were estimated to be 0.231 and 0.984 microg TPCB/g feed, respectively. Because inclusion of PCB-contaminated fish that composed approximately 1% of the diet would reduce mink kit survival by 20% or more, it is likely that consumption of up to 30-fold that quantity of HR fish, as could be expected for wild mink, would have an adverse effect on wild mink populations.

Dietary exposure of mink (Mustela vison) to fish from the Housatonic River, berkshire County, Massachusetts, USA: effects on organ weights and histology and hepatic concentrations of polychlorinated biphenyls and 2,3,7,8-tetrachlorodibenzo-P-dioxin toxic equivalence.

The effects of feeding ranch mink (Mustela vison) diets containing polychlorinated biphenyl (PCB)-contaminated fish (88 gold fish [Carassius auratus] weighing a total of 70.3 kg and 16 carp [Cyprinus carpio] weighing a total of 77.3 kg) collected from the Housatonic River (HR; Berkshire County, MA, USA) in October 1999 on organ weights and histology and hepatic concentrations of total PCBs (sigmaPCBs) and 2,3,7,8-tetrachlorodibenzo-p-dioxin toxic equivalence (TEQ) were evaluated. Diets contained 0.22 to 3.54% HR fish, which provided 0.34 to 3.7 microg sigmaPCBs/g feed (3.5-69 pg TEQ/g feed). Female mink were fed the diets eight weeks before breeding through weaning of kits at six weeks of age. Offspring were maintained on their respective diets for an additional 180 d. The dietary concentration of PCBs that caused a decrease in kit survival (3.7 microg EPCBs/g feed [69 pg TEQ/g]) resulted in a maternal hepatic concentration of 3.1 microg sigmaPCBs/g wet weight (218 pg TEQ/g). Organ weights were not consistently affected. Mandibular and maxillary squamous cell proliferation was apparent in 31-week-old juveniles exposed to as low as 0.96 microg sigmaPCBs/g feed (9.2 pg TEQ/g). Juveniles in this treatment group had a liver concentration of 1.7 microg sigmaPCBs/g wet weight (40 pg TEQ/g). Because inclusion of PCB-contaminated fish, which comprised approximately 1% of the diet, resulted in mandibular and maxillary squamous cell proliferation, it is possible that consumption of up to 30-fold that quantity of HR fish, as could be expected for wild mink, would result in more severe lesions characterized by loss of teeth, thus impacting survivability.