In vitro genotoxic effects of the insecticide deltamethrin in human peripheral blood leukocytes: DNA damage ('comet' assay) in relation to the induction of sister-chromatid exchanges and micronuclei

Deltamethrin, a synthetic dibromo-pyrethroid insecticide, is extensively us ed in agriculture, forestry and in household products because of its high a ctivity against a broad spectrum of insect pests (both adults and larvae), its low animal toxicity and its lack of persistence in the environment. Dat a on the genotoxicity and carcinogenicity of deltamethrin are rather contro versial, depending on the genetic system or the assay used. The aim of this study was to further evaluate the potential genotoxic activity of deltamet hrin. The in vitro genotoxicity of deltamethrin has been evaluated by asses sing the ability of the insecticide to damage DNA (as evaluated using the s ingle-cell microgel-electrophoresis or 'comet' assay) or induce sister-chro matid exchanges (SCE) and micronuclei (MN) in human peripheral blood leukoc ytes. All treatments were conducted with and without the presence of an ext ernal bioactivation source ( +/- S9mix). The results indicate that deltamet hrin, in the presence of metabolic activation ( + S9mix), is able to induce DNA damage (double- and single-strand breaks, alkali-labile sites and open excision repair sites) as revealed by the increasing tail moment values ob served with increasing doses. The frequency of SCE and MN were not statisti cally increased in deltamethrin-treated cells as compared to controls, both with and without S9mix. However, lower deltamethrin doses were tested, as compared to 'comet' assay, because of cytotoxicity. (C) 1998 Elsevier Scien ce Ireland Ltd. All rights reserved.