Studies on the environmental persistence of S-31183 (pyriproxyfen): adsorption onto organic matter and potential for leaching through soil.

Analytical methods were developed to allow the extraction and analysis of S-31183 (pyriproxyfen), 2-[1-methyl-2-(4-phenoxyphenoxy)ethoxy]pyridine, in organic matter from animal waste-water lagoons. Analysis of water and organic debris from a treated lagoon showed that the active ingredient readily adsorbed onto organic matter. S-31183 persisted on organic matter for over a 2-month period, during which time the concentration decayed at an exponential rate. In leaching trials with four different soil types, over 50% of the active ingredient applied remained in the upper 6 cm of a 30-cm soil column; there was no indication of a rapid potential for downward migration. The use of S-31183 for treating wastewater lagoons at doses which are effective for mosquito control did not result in any apparent problems of environmental incompatibility.