Organochlorine pesticides and polychlorinated biphenyls in raw bovine milk from various dairy farms in Beja, Tunisia: contamination status, dietary intake, and health risk assessment for the consumers

We determined organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in raw bovine milk taken directly from the milking equipment for different animals and various farms in Beja region, which is one of the largest milk producing areas in Tunisia. All milk samples were contaminated with one or more pesticides and exhibited measurable concentrations of some PCB congeners. The residue levels are generally marked by the predominance of dichlorodiphenyltrichloroethanes (DDTs) (median: 17.60 ng g(-1) fat), followed by hexachlorobenzene (HCB) (median: 14.31 ng g(-1) fat), PCBs (median: 4.71 ng g(-1) fat), and hexachlorocyclohexanes (HCHs) (median: 0.77 ng g(-1) fat). DDT/DDE ratios across the samples vary between 0.09 to 32.24 and exhibit the hypothesis of sustaining illegal use of the banned pesticide. The historical or recent use of OCPs and possible emission sources of PCBs identified near studied farms may lead to increased levels of these contaminants in produced milk. The estimated daily intake (EDI) values were several orders of magnitude below the tolerable daily intake (TDI) fixed by FAO/WHO, though recorded concentration in some samples exceeded the maximum residue limits (MRLs) fixed by the EU, especially for OCPs. According to health risk assessments, consumption of raw milk did not pose an obvious cancer risk or other health problems for local inhabitants.

Automated summary

In this study, organochlorine pesticides and polychlorinated biphenyls in raw bovine milk from Beja region, Tunisia were analyzed. All milk samples were found to be contaminated with pesticides and contained measurable concentrations of polychlorinated biphenyls. The predominant residue levels were dichlorodiphenyltrichloroethanes, and the varying DDT/DDE ratios suggested the illegal use of banned pesticides. The use of organochlorine pesticides and potential emission sources of polychlorinated biphenyls near the studied farms might lead to increased levels of these contaminants in milk produced. However, consumption of raw milk did not pose an obvious cancer risk or other health problems for local inhabitants according to health risk assessments.