Arsenic Relative Bioavailability Study
The Department of Toxic Substances Control (DTSC) has been awarded a Training Research and Technical Assistance Grant to conduct an Arsenic Relative Bioavailability Study (Study) by the United States Environmental Protection Agency Region IX (USEPA). The goal of the Study is to determine the range of arsenic bioavailability that may exist in contaminated soil at former abandoned mine land (AML) sites and develop better methods to determine the human health effects caused by exposure to arsenic at these sites.
Arsenic is the key chemical of concern at the majority of Brownfield projects at former gold mines in the California Mother Lode. Through implementing the Study DTSC hopes to provide better tools for characterizing AML sites so that bioavailability of arsenic can be employed in risk assessment and risk management decisions, resulting in more cost-effective cleanups.
Currently, toxicity criteria for estimating health effects of arsenic are based on humans exposed to arsenic dissolved in water. However, arsenic at AML sites is bound to soil and rock. To properly describe arsenic risks at AML sites the site-specific relative bioavailability (RBA), which is defined as the ratio of uptake of soil-bound arsenic to arsenic dissolved in water (a ratio of the arsenic that is absorbed in the body from the soil ingestion versus that portion that would be absorbed in the body from water ingestion) must be determined. Currently, the techniques for estimating bioavailability of arsenic are expensive and time-consuming. Animal studies (in vivo bioavailability) could be conducted at each site, but the costs would be prohibitive. The Study will focus on how to predict bioavailability from inexpensive, routine measurements (in vitro bioavailability).
The USEPA grant was awarded in late 2008 and runs for 5 years, terminating in 2013. The current Study is limited to AML sites in the Nevada County area due to budget constraints. If Study results are positive, DTSC intends to expand the geographical area and produce an arsenic bioavailability guidance document that will assist in the proper characterization of arsenic at former AML sites throughout the state, however further activities beyond those planned for this Study will be necessary to achieve this.
For more information or if you have questions, please contact Perry Myers, DTSC Project Manager at (916) 255-3708 or via e-mail firstname.lastname@example.org.