Bioavailability & Exposure Assessment

Exponent scientists are nationally recognized for their work on evaluating the bioavailability of organic chemicals and metals to humans and ecological receptors. Understanding the bioavailability of chemicals is critical to the proper management of contaminated soils, sediments or water, as well as for informing decisions about products. Often, absorption of chemicals from soils or sediment is lower than the absorption in laboratory toxicity studies that form the basis of regulatory values. A site-specific evaluation of bioavailability can be used to produce more realistic estimates of exposure and risk to 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 is at the forefront of this emerging scientific specialty, having studied the bioavailability of many chemicals under widely varying environmental conditions, and for potential impacts on diverse receptors.


We have used the information on bioavailability to develop site-specific cleanup goals for soil and sediments that adequately protect human health and the environment. Our studies have served as benchmarks for others and have helped develop a better understanding of exposures within affected communities and within industry and the regulatory agencies. We have also worked with US EPA to develop guidance documents on the use of new approaches to measure bioavailability. Exponent has been involved in developing and applying site-specific oral bioavailability values for inorganic chemicals (antimony, arsenic, beryllium, cadmium, chromium, lead, mercury, and vanadium) and organic compounds (polycyclic aromatic hydrocarbons, dioxins and furans). Specific examples of contributions in this area include: 

  • Sampling of pore water to successfully demonstrate reduced bioavailability of chromium in sediments 
  • Oversight and use of passive samplers to demonstrate reduced bioavailability of contaminants in sediments 
  • Conducting laboratory experiments to document reduced oral bioavailability of metals in soils that are ingested by small mammals or humans
  • Designing and coordinating original research to evaluate the soil-chemical interactions that affect the oral and dermal bioavailability of PAHs in soil
  • Conducting original investigations to develop inexpensive benchtop (in vitro) methods to predict bioavailability, and validating these methods for use in risk assessment. 

Recent Related Exponent Publications

Ruby MV, Lowney YW, Bunge AL, Roberts SM, Gomez-Eyles JL, Ghosh U, Kissel JC, Tomlinson P, and Menzie C. Oral bioavailability, bioaccessibility, and dermal absorption of PAHs from soil – state of the science. Environ. Sci. Technol. 2016 (accepted for publication).

Ghosh U, Kane Driscoll SB, Burgess RM, Jonker MTO, Reible D, Gobas F, Choi Y, Apitz SE, Maruya KA, Gala WR, Mortimer M, Beegan C. Passive sampling methods for contaminated sediments: Practical guidance for selection, calibration, and implementation. Integrated Environmental Assessment and Management 2014 April; 10(2):210–223.

Burgess RM, Kane Driscoll SB, Ozretich RJ, Mount DR, Reiley MC. Equilibrium Partitioning Sediment Benchmarks (ESBs) for the protection of benthic organisms: Procedures for the determination of the freely dissolved interstitial water concentrations of nonionic organics. U.S. Environmental Protection Agency Office of Research and Development National Health and Environmental Effects Research Laboratory EPA/600/R-02/012 | December 2012.

Kane Driscoll, SB, McArdle, ME, Plumlee, MH, Proctor, D. Evaluation of hexavalent chromium in sediment pore water of the Hackensack River, New Jersey, USA. Environmental Toxicology and Chemistry, 2010 29 (3):617–620.

McArdle, ME, Kane Driscoll, SB, Booth, PN. An Ecological Risk-Based Cleanup Strategy for Contaminated Sediments in a Freshwater Brook, International Journal of Soil, Sediment and Water, 2010 3 (2): Article 4. Available at:



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