Abundance and characterization of microplastics in milk and dairy milk products with a special emphasis on possible health risk assessment: A global systematic review.

The presence of microplastics (MPs) in food products has attracted widespread global attention because of concerns about their potential adverse effects on human health. This study synthesises published data on MPs in milk and dairy products, incorporates a comparative analysis across multiple countries and assesses potential health risks from MPs exposure through dairy consumption. In addition, methodological heterogeneity among the included studies was quantitatively evaluated by examining the effects of analytical techniques, minimum particle-size detection thresholds, and digestion protocols on the reported MP concentrations. The findings demonstrated that MPs concentrations in milk and dairy products ranged from 6 particles/L to approximately 20,200 particles/L. Methodological heterogeneity analysis demonstrated that analytical sensitivity and digestion protocols significantly contributed to inter-study variability, whereas differences among the principal analytical techniques were not statistically significant. Morphological characterisation revealed that fibers and fragments were the dominant forms in the milk matrices. An exposure assessment indicated that children are the most vulnerable population group for infant milk powder (827.75 particles/kg) and human breast milk (1828.92 particles/L) exposure. The MPs contamination factor (MCF) values across all countries and milk and dairy milk matrices predominantly fell within Category IV, corresponding to a very high contamination level classification. However, in packaged milk, countries such as Mexico and Ecuador were categorised within a comparatively lower, yet still significant contamination level. Notably, the microplastic load index (MPLI) values were highest in infant milk powder, followed by those in breast milk and packaged milk. This study provides a comprehensive evaluation of MPs occurrence, methodological heterogeneity, contamination severity, and dietary exposure through milk and dairy products, thereby providing evidence to support policymakers, food safety authorities, and public health initiatives aimed at reducing MPs contamination. Furthermore, the findings align with global sustainability goals, particularly SDG 2 (Zero hunger), SDG 3 (Good health and well-being), SDG 12 (Responsible consumption and production), and SDG 15 (Life on Land).