Heavy metal levels in milk and serum of dairy cows from different farms located near an industrial area

Background: Heavy metals are toxic, non-biodegradable substances able to enter the food chain of cows and then transfer to their milk. This study investigated the relationship between the heavy metal concentrations in serum and milk and the environmental pollutants exposure at two different farms in Ragusa, Italy. Methods: To evaluate the concentrations of aluminum (Al), chromium (Cr), iron (Fe), copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd), and lead (Pb), milk and serum samples were collected from 40 Friesian dairy cows from farm 1 at about 3.7 km from an industrial area (group 1) and 40 Friesian dairy cows from farm 2 at about 400 mt from a greenhouse and 6.0 km from a chemical fertilizer factory (group 2). Results: The concentrations of heavy metals measured in serum and milk showed no statistically significant differences between group 1 and group 2. No significant correlation between heavy metals in serum and milk in group 1 was observed. A positive correlation between Zn concentrations measured in milk and serum samples was observed in group 2 (r = 0.35, p = 0.03). Conclusions: The determination of heavy metals in serum and milk can be an important tool to detect the exposure to environmental pollutants and in monitoring the hygienic state of the environment in which milk is produced.