Bio
Ms. Heather Summers is a toxicologist and risk assessor with technical leadership experience in ecological and human health risk assessment, specializing in bioaccumulation and toxicity of metals and PCBs. She has conducted aquatic and terrestrial ecological risk assessments involving complex ecosystems with multiple receptors, stressors, and assessment endpoints. Ms. Summers is experienced with the unique characteristics of systems characterized by ubiquitous metals contamination. She has led toxicity, bioavailability, and trophic transfer modeling evaluations of highly bioaccumulative metals such as mercury and selenium for the purpose of assessing risks to ecological endpoints in aquatic and terrestrial habitats. Ms. Summers has advised clients on developing site-specific toxicity criteria for the purposes of supporting natural resource damage assessments (NRDAs) and risk assessments at CERCLA sites. She has experience with classical and Bayesian statistics, parametric and nonparametric statistical analysis, and probabilistic modeling.
Ms. Summers has managed numerous field programs to support RI/FS biomonitoring. She has extensive field experience in water, sediment, and biota sampling techniques for freshwater and marine systems. In addition, she has more than 12 years of experience in environmental analytical chemistry instrumentation and detection methods for trace metals, volatile organic and semivolatile organic compounds, and nutrients.
Relevant Experience
Risk Assessment
RI/FS and Risk Assessment for Berry’s Creek, New Jersey — Managed and supported ecological data and risk analysis to evaluate bioaccumulation and toxicity of representative biota and plants exposed to mercury and PCB contamination. Conducted extensive literature review of toxicological studies involving effects of mercury and PCBs in fish and birds. Contributed to study design and directed field implementation of multiyear sampling efforts to support ecological and human health risk assessments. Directed bioaccumulation analysis to support conceptual site model development. Performed a baseline ecological risk evaluation including dose-response modeling and probabilistic risk assessment to support risk management and development of an adaptive remedial design.
Risk Assessment and Natural Resource Damages, Delaware River, Delaware — Participating in concurrent ecological risk assessment and NRDA being conducted for a steel slag fill and bio-solids site located along the Delaware River. Currently managing the conceptual site model, chemical screening, and exposure model development for the ecological risk assessment. Constituents of concern include metals, PCBs, and PAHs. Simultaneously working with the State of Delaware to perform an injury assessment and research early restoration options in anticipation of potential future NRD claim.
Risk Assessment for a Former Wood Treatment Facility, Mississippi — Currently leading strategic development of an ecological risk assessment work plan at a former wood treatment facility under RCRA. Developing field sampling plan for collection of abiotic and biotic media to support ecological exposure assessment of aquatic and terrestrial receptors to PAHs and dioxins.
Creosote Risk Assessment, Southeastern United States — Leading screening-level ecological risk assessment and supporting human health risk assessment associated with PAHs present in groundwater at a former wood treatment facility.
Risk Assessment of Regional Ecosystem Services for Large Marine Ecosystem, Southeast Asia — Provided analytical and research support for an ecological and human health risk assessment related to oil platform decommissioning. Assessed past process water discharges containing mercury and transformation processes associated with methylation of mercury from sediments and overlying water into demersal and pelagic food webs. The risk assessment incorporated multiple lines of evidence, using more than 20 years of research related to regional atmospheric and riverine contributions, mercury isotopic analysis, mercury and methylmercury geochemistry and biogeochemistry, mechanistic modeling of sediment resuspension during 100-year storm events, and platform and regional market fish data. The assessment separated platform risk relative to regional risk and used ecosystem service loss to the local fishery as the common risk metric.
Risk Assessment for Former Mining Site, Illinois — Performed an ecological and human health screening analysis to support identification of chemicals of concern, including lead and other metals, to be evaluated in the risk assessment. Investigated spatial distribution of contamination to develop potential exposure pathways for ecological and human receptors.
Risk Assessment Support for San Jacinto River Waste Pits RI/FS, Harris County, Texas — Assisted in the human health and ecological risk assessments to support the site investigation under CERCLA at a closed facility for storage of bleached kraft pulp mill wastes. Determined exposure point concentrations and evaluated bioaccumulation using statistical software R.
Human Health Risk Assessment for an Oil Refinery, Confidential Location — Completed human health risk assessment for an old oil refinery and transportation and storage terminal. Constituents of concern included petroleum hydrocarbons and PAHs.
South River Ecological Risk Assessment, Virginia — Conducted a relative risk assessment of the effects of mercury contamination in the South River, Virginia, using a Bayesian Belief Network to quantitatively predict the risks to ecological receptors. Performed statistical analysis including a comparative assessment using the Bayesian Belief Network Model and the Relative Risk Model. Conducted in-depth evaluation of mercury bioaccumulation through aquatic and terrestrial food webs to model pathways of transfer and effects to fish and birds. Completed sensitivity and uncertainty analyses to identify key risk factors and guide remediation efforts.
Natural Resource Damage Assessment
NRDA, Asbestos Mining Site, Western United States — Assisting in investigation of a potential NRD claim involving alleged injuries to aquatic and terrestrial habitats from releases of hazardous substances related to asbestos mining activities. Leading technical assessment of toxicological effects and estimates of injury and service losses of key aquatic and terrestrial receptors.
NRDA, Mining Site, Western United States — Currently providing technical consultation for NRD claim involving injuries to surface water and terrestrial habitats allegedly related to releases from mining activities. Constituents of concern include selenium and other metals associated with mining.
NRDA, Former Manufacturing Site, Virginia — Currently providing technical consultation for potential NRD claim for a former industrial site involving alleged injuries to aquatic and riparian resources and groundwater. Constituents of concern include PCBs, mercury, zinc, arsenic, and antimony.
NRDA, Landfill, Confidential Location — Supporting technical investigation and habitat equivalency analysis for a potential NRD claim at a former landfill. Constituents of concern include metals and PCBs.
NRDA, Petroleum Refinery, Colorado — Provided technical consultation to facilitate settlement negotiations for an NRD claim involving alleged injuries to wetlands, aquatic and riparian resources, and waterfowl stemming from a release of refined petroleum product. Investigated technical details of trustee and stakeholder damage claims in an effort to provide accurate information on the magnitude of potential wetland/riparian injuries, resulting service losses, and range of potential restoration/replacement costs.
Litigation Support
Litigation Support Regarding Assessment of Ecological Risks in the Penobscot River, Maine — Provided technical support for the preparation of an expert report, pre-filed direct testimony, pre-filed rebuttal testimony, hearing demonstratives, and testimony support regarding potential impacts on ecological receptors from historical mercury from a former chlor-alkali manufacturing facility in Orrington, Maine. Primary focus was on assessing potential ecological impacts on fish by developing toxicological benchmarks for mercury using point-estimate and probabilistic methods.
Litigation Support Regarding Source Identification and Allocation, Confidential Location — Conducted multivariate statistical analyses including clustering (hierarchical and non-hierarchical), distance and dissimilarity/similarity matrices, and principal component analysis to support client on source identification and allocation negotiations.
Toxicology
Reanalysis of Reference Dose for Dioxin — Conducted a reanalysis of key sources of uncertainty in one of the co-critical studies used by EPA to support the current oral reference dose for 2,4,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and TCDD toxic equivalency (TEQ). Developed a new method for combining data from dose-response studies using Bayesian inference to update probabilities given additional data.
Mercury Toxicity in Songbirds — Conducted literature review and developed toxicity criteria for assessment of reproductive toxicity in songbirds exposed to mercury via the diet.
Mercury and PCB Toxicity in Fish — Conducted literature review of toxicity of mercury and PCBs in fish. Used dose-response models to develop residue-based toxicity criteria for assessing risks to fish.
Selenium Ecotoxicity Assessment — Compiled and critically reviewed literature on toxicity and bioaccumulation of selenium in fish, birds, and cattle. Evaluated the appropriateness of biologically significant endpoints for the development of toxicity reference values. Reviewed sources of uncertainty and their impacts on established toxicity criteria.
Product Stewardship
Development of Database for Environmental Risk Assessment of Cosmetic Ingredients, Nationwide — Developed a database for conducting environmental risk assessment of cosmetic ingredients sold throughout the world, on behalf of an international cosmetics manufacturer. The database included a tiered assessment model that incorporated exposure data and environmental hazard data for conducting a comparison of the predicted environmental concentration and predicted no-effect concentration to be used by the manufacturer in product development decision-making.
Development of Database for Environmental Risk Assessment of Polycarboxylate/Polyacrylate Polymers, Nationwide — Currently developing a database of exposure and hazard data on polycarboxylate/polyacrylate polymers used in cleaning products that will be used to conduct an environmental risk assessment for 26 different polymers.
Site Investigation
Berry’s Creek, Meadowlands, New Jersey — Led and conducted multiple field surveys, including aquatic fauna surveys of the creek and marsh invertebrate sampling, of Berry’s Creek and the surrounding tributaries of the Hackensack River. Developed field sampling plans for evaluating potential food web bioaccumulation of mercury and PCBs. Led field teams and coordinated all aspects of the fieldwork including sample collection, preparation, preservation, and transportation to analytical laboratory. Recent field efforts included marsh invertebrate collection; fish residue biomonitoring, including gut content analysis, sex determination, and otolith collection by dissection; and collection of aquatic food web component, including annelids, fiddler crab, mud crab, grass shrimp, benthic organisms, benthic microalgae, and plankton.
Field Sampling of Waterways near Remediated Landfill, New Jersey — Led field sampling program of sediment, soils, and surface water to address questions of bioavailability of metals. Assessment supported a screening-level ecological risk assessment near a remediated landfill site.
Blackwell Zinc Site, Blackwell, Oklahoma — Conducted effluent and wastewater sampling of Blackwell Zinc site’s groundwater treatment facility and the City of Blackwell’s wastewater treatment plant. Sampling entailed daily collection of aqueous, sludge, and air samples from numerous stages of the groundwater treatment and wastewater treatment facilities to monitor the flow of sludge and the adequacy of digestion in the plant.
Data Management
Database Management and Statistical Analysis — Experience with classical and Bayesian statistics, parametric and nonparametric statistical analysis, and probabilistic modeling. Research and coursework have involved linear regression, descriptive statistics, clustering, and distribution analysis. Statistical software expertise includes Excel, SPSS, R, and Netica.
In-House Statistical Program for Data Exploration and 95UCL Calculation — Created in-house R based program for data exploration, distribution fitting, and calculation of summary statistics specifically to support exposure estimates for risk assessment dose modeling. The software is based upon EPA’s ProUCL Version 5.1.0 software, but improves upon the calculation efficiency of 95% upper confidence limits of means to support complex risk assessments.
In-House Risk Calculation Program — Developed in-house R-based program and relational database of exposure and toxicity parameters to support calculation of exposure dose and hazard quotients for human and ecological risk assessments.
Statistics to Evaluate Remedial Design Alternatives, California — Conducted background hypothesis testing and background threshold value derivation to evaluate remediation design alternatives for an industrial site with background arsenic concentrations. Performed hypothesis testing comparisons of remediation options compared to background concentrations to support remediation design selection.
Education & Credentials
M.S., Environmental Chemistry and Toxicology, Western Washington University, Bellingham, Washington, 2012
B.S., Chemistry (ACS accredited), minors in Mathematics and Environmental Science, Hope College, Holland, Michigan, 2005
Continuing Education
Hazardous Waste Operations and Emergency Response 40-Hour Certification (2012)
Updated 8-Hour Refresher Certification (last update 2018)
First Aid and CPR Certified (2016)
Project Manager Boot Camp Training, PSMJ Resources Inc. (2015)
Professional Affiliations
Member of the Society of Environmental Toxicology and Chemistry
Achievements & Awards
Recipient of 2017 Best Paper Award granted by the Society of Environmental Toxicology and Chemistry (see Landis et al. 2017 in Publications section)
Insights & News
Publications
Spatially referenced environmental exposure model for down-the-drain substance emissions across European rivers for aquatic safety assessments
Publications
Aquatic Risk of Fragrance Materials: Advancing Prioritization in Aquatic Systems
Posters
Environmental Justice Screening Tools: Powerful Platforms with Potential Pitfalls