[en] The standard proposed for elemental phosphorus plants, the subject of this analysis, was 1 curie per year of polonium-210 for each source. There are currently six plants producing elemental phosphorus. EPA sampling of emissions of four plants and estimates of emissions at the remaining two indicate that, with current output levels and operating characteristics, only two plants will be affected by a 1 curie per year standard. Three alternatives to the 1 curie per year standard were considered in performing the regulatory impact analysis: 2.5 Ci/year, 10 Ci/year and no control. For each of these control options and for each plant, the analysis considered the technologies that are available to reduce emissions to the required level, examined the costs of these technologies, identified the least-cost options evaluated the cost per fatal cancer eliminated, and assessed the economic impacts of the regulation