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, OCPs and PCBs were detected in raw bovine milk samples obtained directly from milking equipment of different animals and farms in Beja, a major milk producing region in Tunisia. All milk samples were contaminated with one or more pesticides, and measurable concentrations of PCB congeners were found. DDTs were most predominant, followed by HCB, PCBs, and HCHs. The presence of illegal use of banned pesticides was suggested based on DDT/DDE ratios. The historical or recent use of OCPs and possible emission sources of PCBs near the farms may contribute to the elevated levels of these contaminants in milk. However, the estimated daily intake values were below the tolerable daily intake fixed by FAO/WHO, indicating that consumption of raw milk in this region does not pose significant health risks.