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The avian ecological soil screening level (Eco‐SSL) for Pb (11 mg/kg) is within soil background concentrations for >90% of the United States. Consequently, its utility as a soil screening level is limited. Site‐specific ecological risk–based remedial goals for Pb are frequently many times greater. Toxicity reference values (TRVs) play a major role in defining Eco‐SSLs. The Pb Eco‐SSL TRV is driven by reduced egg production in Japanese quail (Coturnix japonica), which displays effects at doses both substantially lower and greater than other tested species. High variability in egg production in Japanese quail has also been observed for other contaminants. Japanese quail egg production may therefore be too variable and unreliable an effect endpoint upon which to base regulatory screening criteria. Toxicity data supporting the Eco‐SSL were reevaluated and only studies reporting both no and lowest observed adverse effect levels (NOAELs and LOAELs) for reproduction, growth, or survival were considered. Dose–response data were extracted from 10 studies both as concentrations and doses. Dose–response relationships were developed using the US Environmental Protection Agency (USEPA) Benchmark Dose Software for dietary concentrations and doses for egg production in Japanese quail and chickens. Effect levels (of 10%, 20%, and 50%) were extracted from the dose–response analyses. Species sensitivity distributions and dose–response data indicated reproduction was most sensitive to Pb and survival was least sensitive, with growth intermediate. Limited data for ringed turtle doves (Streptopelia risoria) and American kestrels (Falco sparverius) suggest lower sensitivity than chickens to Pb. The ED10 and ED20 thresholds for chickens were 4.4 and 9.8 mg·kg–1·d–1, respectively. Avian Pb Eco‐SSLs were recalculated based on the chicken ED10 and ED20, with and without a bioavailability adjustment. Revised avian Pb Eco‐SSLs for the most highly exposed species (American woodcock), based on the ED10 and assuming 100% and 50% bioavailability, were 36.3 mg/kg and 43.7 mg/kg, respectively. Integr Environ Assess Manag 2019;15:739–749. © 2019 SETAC. Key Points: The avian ecological soil screening level (Eco‐SSL) for Pb (11 mg/kg), which is within soil background concentrations for >90% of the United States, is biased due to the variable and unreliable toxicity reference value (TRV) driven by egg production in Japanese quail egg.Toxicity data from the Eco‐SSL were reevaluated, and reproduction, growth, and survival dose–response data extracted and analyzed for 4 species using the USEPA Benchmark Dose Software, and ED10 and ED20 values for egg production were derived for Japanese quail and chickens.Dose–response data indicated reproduction was most sensitive to Pb (with ED10 and ED20 thresholds for chickens being 4.4 and 9.8 mg·kg–1·d–1, respectively) and survival least sensitive, with growth intermediate.Revised avian Pb Eco‐SSLs for the most sensitive species (American woodcock), based on the ED10 and assuming 100% and 50% bioavailability, were 36 mg/kg and 44 mg/kg, respectively. [ABSTRACT FROM AUTHOR]

Habitat surrounding the inactive Continental Mine in northern Idaho, USA, supports bear (Ursus arctos, Ursus americanus), moose (Alces alces), elk (Cervus elaphus), woodland caribou (Rangifer tarandus caribou), and abundant mule (Odocoileus hemionus) and white-tailed deer (Odocoileus virginianus). Tailings on the mining site were capped and remediated in 2003 to reduce environmental exposure of surrounding soil and sediments of Blue Joe Creek, downslope of the mine. Before capping, the mean Pb concentration in deer pellets collected on-site was 920 mg/kg of Pb (dry wt). This exposure, if chronic, would be comparable to an exposure that could be lethal to cattle or horses. Surprisingly, the mean pellet Pb concentration of 950 mg/kg in 2004 was as high as it was before remediation, and it was related to a high rate of soil ingestion. Mean soil content of the pellets collected from the capped site in 2004 was 22% dry weight, estimated from the acid-insoluble ash, a marker of soil ingestion. Clumps of sand and bits of rock were observed inside some of the pellets, and Pb concentrations in the pellets were correlated (p < 0.05) with soil content. Although terrestrial risk assessments generally estimate exposure from diets and from incidentally ingested soil, the deer at this site were directly ingesting contaminated soil or mining waste. The mean Pb concentration of this ingested soil was estimated as 6,700 mg/kg and the maximum as 25,000 mg/kg, well above the Pb concentrations measured in the remediated cap. The deer seemed to be ingesting soil or mining waste from one or more small but highly contaminated sources located beyond the remediated cap. [ABSTRACT FROM AUTHOR]