Bioavailability & Exposure Assessment

Exponent scientists are internationally recognized for their work evaluating the bioavailability of organic chemicals and metals to humans and diverse ecological receptors. Exponent is at the forefront of this scientific specialty, having studied the bioavailability of many chemicals and their potential impacts under widely varying environmental conditions for decades.

Understanding the bioavailability of chemicals is critical to the proper management of contaminated soils, sediments, and water. Often, absorption of chemicals from soils, sediments, or water is lower than the absorption in laboratory toxicity studies that form the basis of regulatory values. A site-specific evaluation of bioavailability can produce more realistic estimates of exposure and risk to help establish cleanup goals that are scientifically defensible and protective of human health and the environment. Incorporating bioavailability adjustments into human or ecological risk assessments can also provide important insight into the safety of products, which can lead to better-informed decisions for companies and regulators.
Exponent helps public and private sector clients characterize the bioavailability of chemicals in the environment and its influence on potential exposure and risk. We design studies and obtain data and other information that can be used to develop cleanup goals at contaminated sites that are protective of human health and the environment. Exponent has also been involved in the development of site-specific oral bioavailability values and ecological risk for metals (antimony, arsenic, beryllium, copper, cadmium, chromium, lead, mercury, and vanadium) and organic compounds, including polycyclic aromatic hydrocarbons (PAHs), poly- and perfluoroalkyl substances (PFAS), and dioxins and furans. Specific examples of contributions include:

  • Developed guidance with the U.S. Environmental Protection Agency, the U.S. Department of Defense, and state regulators on the use of passive samplers for characterizing bioavailability of contaminants in sediment
  • Used passive samplers in cost-effective laboratory exposures to demonstrate reduced bioavailability of PAHs in sediment from a manufactured gas plant (MGP) site
  • Demonstrated reduced bioavailability of PAHs in sediments as part of a risk-based framework for a series of MGPs in the Midwest
  • Used data on bioavailability of sediment-associated PAHs to reduce the extent of remediation at a former manufacturing and assembly facility
  • Successful demonstrations of limited bioavailability and toxicity of inorganic and hexavalent chromium in sediments adjacent to a chromite ore processing site in New Jersey
  • Designed and coordinated original research to evaluate the soil-chemical interactions that affect the oral and dermal bioavailability of PAHs in soil
  • Assessed the fate, transport, and bioavailability of PFAS in the land-application of biosolids and other residual solids.



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