14C-Propaphos was rapidly absorbed via leaf surface by foliar application and translocated mostly to the upper part of the plant body. By root application, 14C-propaphos was readily absorbed and rapidly translocated to the shoots and levaes, but the radiocarbon was released to the culture solution from the roots when they were transferred to propaphos free solution. The released radioactive compounds consisted of propaphos and propaphos-SO of nearly equal amount. Metabolic reactions included

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... dation of the methylthio sulfur to sulfoxide and sulfone, hydrolysis of the phosphorus-0-phenyl ester, and four of the metabolites were identified. Recovery of radoicarbon from 4 and a half month old rice plant and the soil treated with 14C-propaphos at 3g/are were estimated to be 3.7% (roots), 20% (shoots and leaves), 0.14% (hulls), 0.07% (hulled rice) and 58.2% (soil), respectively. Radioactive residue in hulled rice treated with 14C-propaphos was 0.02ppm; it is below enough compared with the residue limit of 0.05 ppm, and no intact propaphos was detected in it.