A Certified Professional Soil Scientist, he specializes in the study of transport and geochemical fate of toxic pollutants and their environmental effects. He has 34 years of experience conducting and managing environmental studies throughout North America and Europe. He provides scientific and strategic consultation to industrial clients on the design and implementation of CERCLA and RCRA investigations, cost-effective remediation approaches, and negotiations with state and federal agencies. Dr. Shields manages multidisciplinary investigations, risk assessments, and feasibility studies. He investigates the industrial archeology of sites to understand the history of contaminant sources in a given area. He serves as an expert witness in environmental forensics and has testified on the origin, transport, and fate of chemicals in air, soils, sediments, surface water, groundwater, and biota, and exposure of humans and ecological receptors to those chemicals. He has particular expertise in the environmental chemistry and source identification of dioxins and furans, PCBs, PAHs, PFCs, pesticides, and heavy metals and metalloids. Dr. Shields has also testified on the allocation and appropriateness of remediation costs at a variety of sites. He has specialized expertise in the forest products industry and at mining and smelting sites.