Microbiological safety, adulteration, and heavy metal–associated health risks in raw cow and buffalo milk from Punjab, Pakistan

Abstract

Milk is a fundamental component of human nutrition, yet its safety and quality remain major public health concerns in developing countries where raw milk consumption is widespread. This study presents a comprehensive comparative assessment of raw cow and buffalo milk collected from Central and Southern Punjab, Pakistan, focusing on microbiological quality, physicochemical composition, adulteration practices, heavy metal contamination, and associated non-carcinogenic and carcinogenic health risks. A total of 80 raw milk samples (40 cow and 40 buffalo) were collected over a three-month period and analyzed using standard microbiological, chemical, and instrumental techniques, including ICP-AES for heavy metal determination and USEPA models for health risk assessment. Results revealed that both cow and buffalo milk failed to meet international microbiological safety standards, with buffalo milk exhibiting significantly higher total plate counts, coliforms, Escherichia coli, and Staphylococcus aureus. Physicochemical analysis confirmed the superior nutritional composition of buffalo milk, characterized by higher fat, protein, total solids, essential minerals, fat-soluble vitamins, and omega-3 fatty acids. However, widespread adulteration—particularly water addition and the presence of detergents and neutralizers—was observed in both milk types, substantially compromising quality. Heavy metals, especially lead and arsenic, exceeded permissible limits in both cow and buffalo milk, with higher concentrations in buffalo milk. Health risk assessment demonstrated alarming Total Target Hazard Quotient, Hazard Index, and lifetime Cancer Risk values far exceeding acceptable thresholds, indicating significant chronic and carcinogenic risks, particularly for high-consuming and vulnerable populations. Overall, while buffalo milk exhibits superior nutritional and biochemical properties, its safety is severely undermined by poor hygienic practices, adulteration, and environmental contamination. The findings underscore an urgent need for strengthened regulatory enforcement, routine monitoring, farmer education, and improved dairy management practices to ensure milk safety and protect public health in Pakistan.