Ann Holbrow Verwiel, M.P.P.
Senior Managing Scientist


Address1010 B Street
Suite 208
San Rafael, CA 94901



Professional Profile

Ms. Verwiel is a Senior Managing Scientist with ToxStrategies, Inc., and is based in northern California. She has more than 20 years of experience in environmental consulting in the areas of human health risk assessment, site assessment, and environmental regulation. Over her career, she has focused on integrating risk assessment into an overall risk management approach to problem definition, investigation, and mitigation. She has successfully applied this approach in negotiations with regulatory agencies and public groups to develop cost-effective investigations, assessments, and mitigation strategies. She has published and presented papers on a wide variety of topics, including probabilistic risk assessment (Monte Carlo analysis), environmental fate and transport of contaminants, and environmental auditing.

Ms. Verwiel has managed and conducted numerous human health risk assessments that addressed a wide variety of chemicals in soil, soil vapor, air, and groundwater. Petroleum, aerospace, mining, and MGP sites are among some of the most common sites for which she has performed these risk assessments. She has evaluated the chemical signatures, transport mechanisms and ultimate fate, and likely current and future human exposures as key first steps in the health risk evaluation. At sites where volatile organic compounds (VOCs) are present, she has addressed the potential for a vapor intrusion exposure pathway through modeling and measurement, and worked to develop investigation strategies and perform assessments of exposure to indoor and ambient air that included evaluating air emission sources, modeling, soil vapor measurements, and indoor/ambient air measurements.

Ms. Verwiel has a detailed understanding of a broad cross section of environmental regulations, which she has applied to regulatory impact analyses, environmental compliance, and training programs. She has evaluated potential impacts of new regulations on operating facilities and new developments, assessed compliance at operating facilities with a wide variety of environmental regulations, and developed training materials to help regulatory agencies make their requirements clear and to help regulated entities comply. She has conducted air toxic analysis to meet the requirements of Proposition 65, AB2588 Toxic “Hot Spots” Act, and the California Environmental Quality Act (CEQA).

Ms. Verwiel also has communicated risk to formal public groups, such as Restoration Advisory Boards, as well as the general public. She has worked with regulatory public participation specialists, public affairs officers, and others to develop written summaries and presentation materials that convey complex technical issues to the public. She has provided litigation support for several projects involving disputes between owners and operators, alleged air emissions exposures, and California Proposition 65 litigation.