Radionuclides in Milk: A Global Systematic Review and Meta-Analysis and Probabilistic Human Risk Assessment.

This study conducted a systematic review and meta-analysis of radionuclide concentrations of Cesium-137 (Cs-137), Cesium-134 (Cs-134), Iodine-131 (I-131), Lead-210 (Pb-210), and Potassium-40 (K-40) in milk worldwide, along with an assessment of human health risks, in accordance with the PRISMA guidelines. Pooled radionuclide concentrations were estimated using a random-effects model, while excess lifetime cancer risk (ELCR) was calculated to evaluate carcinogenic effects using the Monte Carlo Simulation (MCS) model. A comprehensive search of Scopus, PubMed, Embase, and Web of Science identified 66 papers (200 data reports, 2000-2025) that cover milk samples from 32 countries. The global pooled mean concentrations (Bq/L) followed the order: K-40: 57.494 > Cs-137: 0.904 > I-131: 0.301 > Pb-210: 0.136 > Cs-134: 0.032. Extreme concentrations were observed in the United Kingdom (Cs-137: 288.000), Syria (I-131: 76.000; K-40: 243.500), and India (Pb-210: 1.080), whereas Mali (Cs-137: 0.003) and Algeria (K-40: 2.349) showed the lowest levels. Probabilistic human health risk assessments revealed that the mean cancer risk (CR) for adults from Cs-137 ingestion exceeded the acceptable limit (1E-4) in the United Kingdom, Austria, South Korea, Serbia, the Czech Republic, Germany, Kazakhstan, and Iceland. For Cs-134, the CR in Finland and France remained below the limit. The CR from K-40 exceeded the limit in Spain, Syria, Bangladesh, Mali, Iraq, Singapore, Thailand, Japan, Italy, and Turkey. For I-131, the limit was exceeded in Syria, Romania, Greece, and Spain. The CR of Pb-210 exceeded the limit in Tunisia, Slovenia, India, the Czech Republic, Italy, and Syria. These disparities reflect variations in environmental contamination, nuclear legacy, and regulatory standards. The results highlight the necessity for strict monitoring, especially in high-risk areas, and promote enhanced agricultural practices and food safety policies to reduce radionuclide exposure through milk consumption.