Pesticide residues in milk and their relationship with pesticide contamination of feedstuffs supplied to dairy cattle in Punjab (India)

The aim of the present study was to investigate the correlation between pesticides contamination of feedstuffs supplied to dairy cattle and pesticide residues in bovine milk. The animal concentrate feed, fodder, water and milk samples were collected from 55 dairy farms in Punjab (India) representing intensive production and typical feeding management. The concentrate feed, fodder/silage, water and milk samples were extracted by multiple residue methodology and pesticide residues concentration was estimated by gas chromatography. It was shown that chlorpyrifos pesticide was the main contaminant detected at mean level of 6.01, 4.05 and 2.58 ng · g⁻¹ in concentrate feed, fodder and milk samples, respectively. Other pesticide residues observed in feed and milk samples were: endosulphan sulphate, cypermethrin, ethion, p,p’-DDE, lindane, malathion and fenvalerate. Chlorpyrifos was the only pesticide detected in one water sample. Though the mean residue levels of pesticides were substantially below the maximum residue limits (MRL), individually two milk samples exceeded the MRL value for lindane (1.0 ng · g⁻¹) and three for DDT (20.0 ng · g⁻¹) and chlorpyrifos (20.0 ng · g⁻¹). Two milk samples also violated the MRL value (10.0 ng · g⁻¹) for endosulphan sulphate residues. However, none of the samples was found above the MRL (50.0 ng · g⁻¹) for cypermethrin. The relationship between occurrence of pesticide residues in feedstuff and milk might suggest that animal feed is the main source for appearance of pesticides in milk. However, environmental contamination with pesticides, lack of good management practices while using pesticides and violation of withdrawal period for ectoparasiticides may also result in the occurrence of pesticide residues in milk.