An overview of USEPA's integrated multimedia, multi-pathway, and multi-receptor exposure and risk assessment tool - The 3MRA model

Risk based tools are often useful for making quick yet informed decisions regarding the threats posed by a waste, an emission, or a remedial setting. Such tools may prove useful in Brownfields settings where the primary objective is returning properties to productive use in the most efficient manner possible. This paper chronicles the development of a state-of-the-art risk based standard setting tool, USEPA's Multi-media, multi-pathway, multi-receptor exposure and risk assessment tool - the 3MRA model. The history of its development, nature of the data, the establishment of a site-based approach, the underlying Monte Carlo scheme, the unique software design, and the potential future applications are summarized.