Department of Entomology, Punjab Agricultural University, Ludhiana, 141 004, India
Online published on 15 December, 2011.
Following the application of 10% technical HCH dust @ 2.5 kg a.i./ha on rice crop at the flowering stage, residues of its different isomers were estimated in soil and various fractions of rice crop at harvest time. In all the matrices. β- and δ-HCH were present in proportion greater than that in technical HCH. Amongst the different fractions of fice crop, rice bran contained maximum residues, followed by-straw, husk and rice grains. Boiling of rice grains did not result in any loss of HCH residues. The use of rice bratt and straw from HCH treated crops as feed for milch cattle was shown to cause significant contamination of milk. Theoretical Daily Intakes of various isomers of HCH were estimated and compared with their respective Acceptable Daily Intakes to ascertain the toxicological significance of the residues. Major problems of environmental contamination and human exposure from the use of technical HCH were found to arise from its noninsecticidal β and δ-isomers, while the insecticidal γ-isomer did not seem to constitute any hazard.
