Assessment of heavy metal contamination in raw milk for human consumption

The presence of heavy metals in various farm inputs, including feed, fertilizer, water and environment leads to excretion of the residues in animals' milk. Because consumption of milk contaminated with heavy metals poses serious threats to consumers' health, a study was conducted in 2012 - 2013 in Pakistan to evaluate the concentration of heavy metals in unprocessed raw milk procured in different seasons from Jhang city, Punjab, Pakistan. A total of 400 milk samples was collected from milk shops and dairy farms, and the contents of heavy metals, i.e. copper (Cu), lead (Pb), cadmium (Cd) and chromium (Cr) were analysed via atomic absorption spectrometry. Results indicated that the average concentrations of Cu, Pb and Cd were significantly higher than International Dairy Federation Standards. Within a season, heavy metal levels differed significantly among samples. For each type of milk source, there was a significant difference in mean concentration of heavy metals between summer and winter. Based on these findings, there is a critical need to set legal limits and surveillance for heavy metals in an animal's milk.