Assessment of milk contamination by some heavy metals (lead, cadmium, chromium, nickel and mercury) of dairy cattle herd in Qazvin province and its effects on human health

The aim of this study was to evaluate the concentration of some heavy metals in the milk produced by dairy farms in Qazvin province. For this study, milk samples of 35 industrial dairy herds under the auspices of the Livestock Breeders Union of Qazvin province in different cities including Abyek, Qazvin, Takestan, Buin Zahra and Alborz were collected by direct reference in two consecutive days. Immediately after sampling, the samples were sent to a specialized laboratory for measuring levels of heavy metals including lead, cadmium, chromium, nickel and mercury. Then, the obtained data were analyzed in a completely randomized design. The results showed that the concentrations of lead, cadmium and chromium in the produced milk were 1.43± 3.77, 0.70± 2.24 and 1.07±1.27 μg / kg respectively.  There was no significant difference in the concentration of these elements among different cities. The concentrations of nickel and mercury in the produced milk were 0.63± 0.30 and 0.39± 0.37 μg / kg respectively. In terms of nickel and mercury concentrations, the difference between different cities of the province was significant and in Abyek was higher than others (P=0.02 and p=0.02 respectively). In conclusion, concentrations of heavy metals (lead, cadmium, chromium, nickel and mercury) in milk produced in dairy farms was less than the standard levels, thus milk produced in Qazvin province can be considered as a healthy product from heavy metals (lead, cadmium, chromium, nickel and mercury) for human consumption.