Gradient has extensive experience in evaluating sources, exposures, and potential human health and ecological risks at mining and smelting sites. We have provided expert technical support for permitting new mine developments. We have developed in-depth transport models, performed forensic evaluations, and investigated numerous exposure pathways, including fugitive dusts, surface and drinking water, sediments, soils, groundwater, livestock, wildlife, and plants. Gradient scientists provide reliable assessments of biologically relevant exposures and potential toxicological impacts. We apply innovative risk assessment approaches and interact with government agencies to develop scientifically sound risk management and site closure plans for our clients.
What We Do:
Site Assessment
Environmental Chemistry and Transport Analysis
Human Health and Ecological Exposure and Risk Assessment
Permitting, Regulatory Comment, and Compliance
Publications:
Goodman, JE; Espira, LM; Zu, K; Boon, D. 2024. “Quantitative recall bias analysis of the talc and ovarian cancer association.” Glob. Epidemiol. 7:100140. doi: 10.1016/j.gloepi.2024.100140.
Bowers, T; Drivas, P; Mattuck, R. 2014. “Prediction of soil lead recontamination trends with decreasing atmospheric deposition.” Soil Sediment Contam. 23(6):691-702. doi: 10.1080/15320383.2013.857294.
Project Examples:
Multi-disciplinary Scientific Support Near a Former Zinc Smelter. Gradient evaluated property damage and medical monitoring records for residents near a former zinc smelter. We evaluated the variability in exposure to metals from soil among the residents and quantified this variability to assess the scientific basis of class certification. We also identified alternative sources of metals in the area based on metal concentration ratios, historical aerial imagery analysis, and flood information. Our analyses were used to develop remediation approaches and costs.
Lead Smelter Baseline Ecological Risk Assessment. As part of a Resource Conservation and Recovery Act (RCRA) facility investigation, Gradient performed a baseline ecological risk assessment (BERA) for a former lead smelter site. We identified field sampling plans for the collection of sediment, soil, surface water, and wildlife tissue. The BERA characterized risks based on site-specific bioavailability and toxicity to aquatic organisms, birds, mammals, and amphibians, and aided in remedial decisions for the site.
Evaluation of Potential Human Exposures to Media Influenced by Mining Operations. Gradient performed a human health risk assessment for a copper and gold mining site to support ongoing environmental monitoring and remedial activities. We investigated multiple exposure pathways, including exposure to metals in fugitive dust, surface water, sediments, soils, drinking water, groundwater, plants, and aquatic tissues.
Risk Assessments at a Former Barite Mining Site. Gradient performed human health and ecological risk assessments to facilitate a remedial strategy at a former barite mining site affected by multiple metals. We evaluated exposures to contaminants in soil, surface water, sediment, and fish and shellfish, and reviewed historical data. We designed a comprehensive sampling program to fill data gaps, evaluate site-specific contaminant bioavailability, and define the need for remediation.
Permitting Support for Critical Minerals Project. Gradient provided scientific support and communications regarding air quality permitting from a state environmental quality agency for a critical mineral exploration and development project. We evaluated potential manganese emissions and health risks to nearby residents, as well as air modeling results and background manganese concentrations in ambient air. In addition, we evaluated human health risks from ambient air exposures to metals, hazardous air pollutants (HAPs), and dust deposition-related effects on threatened and endangered species to support the EIS process.
Risk Assessment at a Copper Mine and Tailings Pond. Gradient assessed human health risks near an active open pit copper mine and tailings ponds. We worked closely with the state agency, the mining company, and other consultants to ensure the appropriate use of risk assessment throughout the remedial investigation/feasibility study (RI/FS) process, including data collection and risk communication. We used a novel probabilistic analysis to derive soil cleanup levels for copper based on a nausea endpoint, which helped the state agency to establish the first US soil cleanup level for copper and was the basis of a peer-reviewed publication.
Risk Assessment at a Secondary Lead Smelter. Gradient performed risk assessments for lead in soil on properties surrounding a RCRA battery manufacturing, recycling, and lead smelting facility. We participated in a blood lead study to determine if residents had been impacted by elevated lead levels in soil; the results of this study were used to modify US EPA’s default inputs to the IEUBK model. Gradient calculated site-specific soil lead cleanup levels for residential and recreational areas surrounding the facility, and participated in negotiations with the regulatory agency.
In the News:
US EPA Releases New Guidance for Assessing Intermittent or Variable Lead Exposures – September 18, 2024
Trends: US Manufacturing and Mining – Winter 2024
