Assessment of arsenic, cadmium, and lead in biological and environmental matrices in dairy production systems in Isfahan, Iran.

Background: Contamination with heavy metals such as arsenic (As), cadmium (Cd), and lead (Pb) in dairy production systems poses significant public health risks due to their bioaccumulative nature. Aims: This study investigated the levels of As, Cd, and Pb in multiple matrices within dairy farms in Isfahan Province, Iran, and assessed associated health risks, particularly among children. Methods: A total of 180 samples (water, milk, feed, feed supplements, manure, and tail hair) were collected from 30 industrial dairy farms. Samples were stratified by herd size, milk yield, and proximity to industrial zones. Metal concentrations were analyzed using atomic absorption spectroscopy. Hazard quotients (HQs) for Pb exposure through milk consumption were estimated. Results: Pb levels in raw milk exceeded national standards (0.02 mg/L) in over 50% of farms, particularly in small, and those located near industrial areas. Cd and As levels in milk were generally below detection limits, though As, Cd, and Pb exceeded regulatory limits in tail hair on a significant number of farms. Strong and significant correlations were observed between Pb levels in milk and those in supplements (r Conclusion: Contamination in small farms near industrial zones underscores the need for more stringent feed quality regulations and more frequent biomonitoring using non-invasive markers like tail hair, which has proven effective as a biomarker for chronic metal exposure.