Studies on levels of some heavy metals and polychorinated biphenyls,PCBs, in milk and milk products

This study was conducted to determine some contaminants in milk such as heavy metals (Cd, Pb, Fe, Zn, Cu and Cr) and, PCBs (28, 52, 101,138,153 and 180), in milk and milk products. Survey in seven different Egyptian regions and during 3 seasons of one year (2009) was carried out .The effect of manufacturing process of some dairy products (fresh cheese ,Ras cheese, yoghurt and fatty products) on levels of these contaminants was also studied. According to the results obtained it could be concluded that : The most polluted samples were obtained from Shubra. As regards to seasonal variation Cd, Zn, and Cr showed the highest levels of pollution in Jan. -Feb. scason, while Pb, Fe and Cu showed the highest pollution in May- June, the most polluted season is May _June. Referring to dairy products the results obtained recorded about 70-80 %reduction in heavy metals concentration in cheese as compared to that of raw milk. Ras cheese displayed the highest reduction. Concerning yoghurt, the results indicated that levels of studied metals were lower than that of the levels in raw milk by 0,50, 17.04, 15.3, II and 10.6 % for Pb, Cd, Fe, Cr, Cu and Zn, respectively. For fatty product ghee has the lower retention of heavy metals (0-4%).Regarding, the survey of PCBs it can be concluded that The most contaminated region by PCBs is Menofia (l0ng/ g fat), and May June was the highest polluted period. Concerning to processed dairy products they obtained results showed that :Using UF -technique lead to reduction of Ó PCBs. And all congeners concentration as well as sum of all Ó PCBs were decreased gradually till the end of ripening period of Ras cheese. Some congeners are degraded by microbial process in yoghurt manufacture .Congeners PCB 138, 153 and 180 were the most abundant in all fatty products samples. In conclusion, its worthy to note that non of the evaluated milk products samples in the present study exceeded the maximum level set by European community (100 ng/ g fat).