Insecticide residues in soils on 16 farms in southwestern Ontario--1964, 1966, and 1969
Harris, C.R.; Sans, W.W.
Pesticides Monitoring Journal 5(3): 259-267
1971
ISSN/ISBN: 0031-6156 PMID: 5164327 Document Number: 42703
Studies were carried out on 16 farms in south-western Ontario in 1964, 1966 and 1969 to determine the extent to which residues of insecticides were accumulating in agricultural soils as a result of current insect control practices. Residues of organochlorine insecticides were present in soils on all 16 farms. DDT and its metabolites DDE and DDD occurred on all the farms, aldrin or dieldrin or both on 14, and heptachlor, heptachlor epoxide and gamma chlordane on 6. Other organochlorine compounds detected included dicofol in orchards, endrin, trace amounts of gamma BHC (lindane), and endosulfan. The highest average residues of organochlorine compounds were found in orchards, followed by vegetable fields, tobacco fields and field-crop soils. The use pattern indicated that organochlorine insecticides were used almost exclusively between 1961 and 1964, while organophosphorus insecticides were used increasingly between 1965 and 1969. Residues of organochlorine insecticides in soil appeared to be consistent with the use pattern, since they were highest in 1966 and declined by 1969 to levels similar to those found in 1964. Preliminary data indicated that the increasing use of organophosphorus insecticides is resulting in residues of some of these compounds in soils in which vegetables are grown.