Evaluation of conventionally and organically produced vegetables for high lipophilic organochlorine pesticide (OCP) residues

The occurrence and distribution of highly hydrophobic organochlorine pesticide (OCP) in vegetables cultivated under organic and conventional conditions were evaluated. OCP residues in aerial and subterranean tissues of two varieties of lettuce and chard together with the soil where they grown were GC-ECD analyzed. ΣDDTs > ΣChlordane > ΣHeptachlor > ΣAldrins was the OCP distribution pattern in all samples. Conventional soils had higher OCP residues than organic one, even though levels were bellow 5 ng/g dry weight, indicative of low polluted agricultural environments. Vegetables accumulated OCP efficiently with residue levels 4× to 45× fold greater than those of soils. OCP tissue-dependent distribution was found to be upon the physicochemical characteristics of the pollutants (Koa and Kow). Lettuce showed a high variability in pesticide uptake regarding varieties and tillage practices. In spite of analyzed pesticides are banned or restricted, edible tissues of vegetables from both farms showed detectable residues of these compounds even though at levels below the allowed by the Codex Alimentarius. Thus, environmental conditions like presence or absence of trees, hedgerows or nearby to conventional farms influence on OCP occurrence and levels in vegetables organically grown.