Resumen

FRANCIS, Pierre  y  BETANCOURT, Pedro. Residues of organochlorines and organophosphorus pesticides in onion crop in Quibor depression, Venezuela. Bioagro [online]. 2007, vol.19, n.2, pp.69-78. ISSN 1316-3361.

ABSTRACT The accumulation in onion crops of organophosphorus (OF) and organochlorines (OC) pesticide residues in production systems that used pest chemical control in Quíbor Depression, Lara State, Venezuela, was evaluated. Three representative onion production systems were selected, registering all types of pesticides used during the crop cycle. At the end of crop cycle, samples of onion were taken and analyzed by gas chromatography to determinate levels of OF and OC residues. The results indicated a main use of fungicides, use of highly toxic OC and OF insecticides, overdosage, and high number of applications. Onions of two of the studied systems showed residues of the herbicide OC butachlor ranging from 0.86 to 1,80 mg·kg^-1, which were considered unacceptable. Residues of the insecticide OF chlorpiryfos were detected in the three systems with means between of 0.01 and  0.02 mg·kg^-1, values that did not reach the maximum residue level established by FAO and EPA. In one of the systems 0.02 mg·kg^-1 of residues of the insecticide OF dimethoate were detected, although below the maximum residue level according to FAO. The paper concludes that there was a relation between the inadequate use of pesticides and the presence of residues in the harvested onion

Palabras clave : Insecticide; fungicide; herbicide; toxicity.