Colorado's plutonium-in-soil standard

Colorado adopted a plutonium-in-soil standard in 1973. This standard, considered conservative at the time of adoption, was based on the then-identified nature of soil sampling, the then-available ambient air plutonium concentrations associated with contaminated soil and the unknown risk associated with general public exposure to such materials. With the availability of additional information, the standard was re-evaluated and this paper is a summary of that effort