Dissipation and degradation of 14C-DDT in Malaysian soils

The rates of dissipation and degradation of the insecticide DDT were studied under field conditions in Malaysia, using a 14C-labelled chemical. Over a period of one year, extractable, soil-bound and total 14C-activity were recorded. Half of the 14C-activity dissipated from soil after 24 weeks. Extractable DDT showed a half-life of only 10 weeks; 90% of the chemical dissipated after 20 weeks. The formation of DDE as a principal metabolite increased with time and accounted for approx. 60% of the extractable residue after 20 weeks. There was also a gradual significant increase in the formation of soil-14C-bound residues which reached 50% of the total residue after 52 weeks. The data strongly suggest the near-complete dissipation of DDT in less than half a year; the major products (50% of the initially applied chemical) being extractable DDE and bound pesticide residues. (author). 3 refs, 2 tabs