Human biomonitoring in support of the Minamata Convention: a case of phasing out dental amalgam

This study analysed urinary mercury (U-Hg) concentrations in 1412 Slovenian children across four human biomonitoring campaigns conducted between 2007 and 2024. Median U-Hg levels declined from 0.76 ng mL−1 (0.72 µg g−1 creatinine) in the 2007 PHIME cohort to 0.22 ng mL−1 (0.21 µg g−1 creatinine) in the 2018–2024 SLO-HBM-II cohort, paralleling a decrease in the prevalence (from 65 to 3%) and the average number of dental amalgam fillings in children. Multilevel mixed-effects models showed a consistent temporal decline in U-Hg that persisted after adjustment for demographic and environmental covariates. In contrast, the inclusion of the amalgam number substantially attenuated the time trend, indicating that reduced amalgam use likely contributed to the observed decrease. As amalgam prevalence fell, other sources of exposure, such as fish consumption, became relatively more prominent predictors of U-Hg, while children living in historically Hg-contaminated areas showed persistently higher levels. Although Slovenia had already phased down dental amalgam in children before ratifying the Minamata Convention, these long-term biomonitoring data illustrate how changes in exposure sources are reflected in internal Hg levels. The study demonstrates the value of repeated national HBM programmes for identifying dominant exposure pathways, investigating their evolution over time, and providing evidence relevant to effectiveness-evaluation frameworks under Article 22 of the Minamata Convention. ▪ Phase-out of dental amalgam in children is reflected in decreasing urinary mercury ▪ Predominant exposure sources have shifted from dental amalgam towards dietary and environmental ▪ HBM is a key tool for evaluating exposure trends and informing policy decisions ▪ Continued HBM is essential for exposure assessment and health protection