Contaminación de leche materna por el plaguicida organofosforado clorpirifos de madres residentes en tres poblaciones agrícolas del estado Mérida, Venezuela

This study determined the concentration of organophosphorus chlorpyrifos in breast milk samples of mothers residing in three rural towns of Merida State, Venezuela, by gas chromatography with electronic capture detector. Chlorpyrifos is a white solid insecticide with a strong, crystalline appearance. It is widely used in housing and agriculture. The chlorpyrifos, is used to control ticks in cattle and in form of spray for the control of harvest pests. Experimentally, an analytical methodology was used to determine chlorpyrifos in breast milk by solid phase extraction. C-18 cartridges were used for the retention of the pesticide and elution was achieved with n-hexane and dichloromethane. Subsequently the cleaning of the extract was carried out in columns of silica acidified with sulfuric acid. The percentages of recovery of the applied extraction method oscillate between 70 and 72%. A total of 60 breast milk samples were analyzed, from 15 mothers who had between 3 and 8 weeks postpartum, who were followed continuously for four weeks. The lipid percentages of the analyzed milk samples are between 0.4% and 7%. Chlorpyrifos is present in 88% of the analyzed breast milk samples and the concentration range is between 0.03-1.7mg/Kg of lipids. All the samples where the chlorpyrifos was quantified exceed the Maximun Residue Limit for this pesticide.