Heavy metal contamination in milk: An evaluation of sources, detection methods and health implications for human population

Background, Context or Rationale Milk is a widely consumed and nutritionally important food, particularly for children and other vulnerable populations. However, contamination with heavy metals has become an increasing global public health concern. Understanding contamination levels, sources, and associated health risks is essential to ensure milk safety and guide regulatory decision‐making. Aim(s) This review aimed to synthesise global evidence on heavy metal contamination in milk from major livestock species (cow, buffalo, goat, camel, and sheep), evaluate associated human health risks, and identify spatial risk patterns to support food safety management and regulatory priorities. Methods Peer‐reviewed studies published between 2000 and 2025 were systematically reviewed to analyse concentrations of As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb and Zn in milk from Bangladesh, Croatia, Egypt, Ethiopia, India, Iran, Mexico, Nigeria, Algeria, Peru, Iraq, South Africa, Columbia, China, Slovakia, Turkey, Yemen, Pakistan, Italy, Kazakhstan and Saudi Arabia. Data on milk type, sampling location, analytical methods, and health risk parameters were extracted. Heavy metals were mainly analysed using AAS, ICP‐OES and ICP‐MS. While health risks were assessed using DIM, HRI, THQ and HI. Major Findings Heavy metal concentrations in milk varied substantially across countries and milk types. Cow milk exhibited elevated Cu, Zn and Fe levels in Pakistan, India, Egypt, Peru and Mexico, while buffalo milk showed higher Mn, Cu, Fe, Pb and Zn contamination in India, China and Pakistan. Goat milk from Pakistan exceeded levels reported in Italy, China and Croatia, particularly for Fe, Mn, Pb and Ni. Camel milk contamination was highest in Kazakhstan and Saudi Arabia, dominated by Zn, Mn and Pb, whereas sheep milk showed the greatest overall contamination in Saudi Arabia, Pakistan, Turkey and Iran, with Mn, Pb and Zn as major contributors. Health risk assessment indicated exceedance of safe thresholds (HI > 1) in multiple regions, with sheep milk presenting the highest cumulative risk, followed by goats', cows', camels', and buffaloes' milk. Spatial risk stratification based on cumulative HI values further distinguished regions including, India, Bangladesh, Saudi Arabia, China and Egypt, with elevated long‐term exposure potential from those with comparatively lower risk regions, such as Pakistan, South Africa and parts of Iran, supporting region‐specific risk prioritisation. Scientific or Industrial Implications The findings highlight the need for strengthened monitoring, improved feed and water management, stricter regulatory enforcement and cleaner dairy production practices to ensure milk safety and protect public health.