AWWA CO50836

Prospective Groundwater Monitoring (PGW) studies conducted by the registrant DowAgrosciences in the states of Wisconsin and Florida have demonstrated that 1,3-Dichloropropene (1,3-D) and two major degradates have the capacity to leach to and persist in groundwater. In the Wisconsin Study, concentrations in groundwater (15-20 foot depth) of 1,3-D plus the two degradates reached as high as 4040 ug/L, with a time-weighted annual average concentration of 357 ug/L. In the Florida study, concentrations in groundwater (10 foot depth) of 1,3-D plus degradates ranged up to 39.5 ug/L, with a time-weighted annual average concentration of 1.15 ug/L. 1,3-D has been classified by EPA as a class B2 (probable human) carcinogen. The recently enacted Food Quality Protection Act (FQPA) requires EPA to comprehensively consider drinking water as a separate source of exposure in human dietary risk assessments. Populations which may be the most exposed consist of people living near treated fields who consume untreated water from domestic wells which tap into vulnerable groundwater. In order to better define and address these exposure concerns, measures include a combination of tap water monitoring focused on these populations, and label changes designed to restrict use in vulnerable areas. Includes 13 references, tables, figures.