Regulatory considerations for the potential development and application of metal cleanup values

The development of media-specific ecological values for risk assessment includes the derivation of acceptable levels of exposure for terrestrial wildlife (e.g., birds, mammals, reptiles, and amphibians). Although the derivation and subsequent application of these values can be used for screening purposes, there is a need to identify toxicological effects thresholds specifically for making remedial decisions at individual contaminated sites. A workshop was held in the fall of 2012 to evaluate existing methods and recent scientific developments for refining ecological soil screening levels (Eco-SSLs) and improving the derivation of site-specific ecological soil clean-up values for metals (Eco-SCVs). This included a focused session on the development and derivation of toxicity reference values (TRVs) for terrestrial wildlife. Topics that were examined included: methods for toxicological endpoint selection, techniques for dose-response assessment, approaches for cross-species extrapolation, and tools to incorporate environmental factors (e.g., metal bioavailability and chemistry) into a reference value. The workgroup also made recommendations to risk assessors and regulators on how to incorporate site-specific wildlife life history and toxicity information into the derivation of TRVs to be used in the further development of soil cleanup levels.

Section: Case Examplementioning

confidence: 99%

Furthering the derivation of predictive wildlife toxicity reference values for use in soil cleanup decisions

Mayfield

Johnson

Burris³

et al. 2013

“…Soil microbial processes have been incorporated successfully into soil risk assessment in other national and international regulatory schemes, and the workgroup recommends their application to Eco-SCV development and clean up of contaminated sites in North America. Greenberg et al (2014) note that, because of the great potential for more immediate and widespread use of normalizing factors to adjust soil values to site-specific soil chemistry, an easily accessible compendium of approaches and normalizing factors is needed. They also noted that this approach depends on collecting the required information during soil analyses conducted in support of the risk assessment.…”

Section: Soil Microbial Processesmentioning

confidence: 99%

“…Greenberg et al () note that, because of the great potential for more immediate and widespread use of normalizing factors to adjust soil values to site‐specific soil chemistry, an easily accessible compendium of approaches and normalizing factors is needed. They also noted that this approach depends on collecting the required information during soil analyses conducted in support of the risk assessment.…”

Section: Overviews Of Articles In the Seriesmentioning

confidence: 99%

“…They also noted that this approach depends on collecting the required information during soil analyses conducted in support of the risk assessment. Additionally, Greenberg et al () point out that the variability in standardized toxicity tests for soil biota makes it difficult to calculate precisely low‐effect values (such as the concentration where 10% of the test population would be affected). Therefore, an effect concentration between 25% and 50% is recommended for all endpoints when setting Eco‐SCVs.…”

Section: Overviews Of Articles In the Seriesmentioning

confidence: 99%

See 1 more Smart Citation

Next steps in the development of ecological soil clean‐up values for metals

Wentsel

Fairbrother

2013

This special series in Integrated Environmental Assessment Management presents the results from 6 workgroups that were formed at the workshop on Ecological Soil Levels-Next Steps in the Development of Metal Clean-Up Values (17-21 September 2012, Sundance, Utah). This introductory article presents an overview of the issues assessors face when conducting risk assessments for metals in soils, key US Environmental Protection Agency (USEPA) documents on metals risk assessment, and discusses the importance of leveraging from recent major terrestrial research projects, primarily to address Registration, Evaluation, Authorization and Restriction of Chemical Substances (REACH) requirements in Europe, that have significantly advanced our understanding of the behavior and toxicity of metals in soils. These projects developed large data sets that are useful for the risk assessment of metals in soil environments. The workshop attendees met to work toward developing a process for establishing ecological soil clean-up values (Eco-SCVs). The goal of the workshop was to progress from ecological soil screening values (Eco-SSLs) to final clean-up values by providing regulators with the methods and processes to incorporate bioavailability, normalize toxicity thresholds, address food-web issues, and incorporate background concentrations. The REACH data sets were used by workshop participants as case studies in the development of the ecological standards for soils. The workshop attendees discussed scientific advancements in bioavailability, soil biota and wildlife case studies, soil processes, and food-chain modeling. In addition, one of the workgroups discussed the processes needed to frame the topics to gain regulatory acceptance as a directive or guidance by Canada, the USEPA, or the United States.

“…New approaches in determining threshold values have gained acceptance in the European Union's Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) program. These include use of the HC5 (concentration hazardous to 5% of species) from the species sensitivity distribution (SSD) and use of concentration response functions instead of no observed adverse effect levels (NOAELs) as an appropriate endpoint (Allard et al ; Greenberg et al ; Sample, Schlekat et al ). The authors also recognize that the toxicity reference value (TRV; 1.63 milligrams of Pb per kilogram per day) used to estimate the Eco‐SSL is problematic.…”

Section: Introductionmentioning

confidence: 99%

Revisiting the Avian Eco‐SSL for Lead: Recommendations for Revision

Sample¹,

Beyer

Wentsel³

2019

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.