20.500.12556/DiRROS-31516 Non-linear hair-to-blood mercury partitioning in a chronically exposed Amazonian population Human biomonitoring of mercury (Hg) exposure commonly relies on blood and hair measurements, often assuming a stable conversion ratio between these matrices. However, this assumption neglects dynamic toxicokinetic processes governing Hg distribution and elimination. Here, we characterized the distribution, determinants, and toxicokinetic implications of the hair-to-blood total Hg ratio in 453 individuals from Amazonian riverine communities chronically exposed to methylmercury (MeHg). Total Hg (THg) was determined in blood and hair, Hg speciation in hair by LC-ICP-MS, and selenium (Se) in blood was measured by ICP-MS. Model-based estimates of MeHg intake and Hg excretion were derived, and linear, non-linear, and multivariable analyses were applied. Blood and hair THg were strongly correlated (R = 0.86, p < 0.0001), confirming hair as a robust biomarker of chronic exposure. However, the hair-to-blood ratio showed high inter-individual variability (median 303; range 73.6–2132) and a significant inverse association with blood THg (β = − 0.394, p < 0.001), indicating non-linear partitioning. Blood Se levels were elevated and positively associated with the ratio (β = 1.081, p < 0.001). Estimated MeHg intake exceeded the USEPA reference dose by over tenfold. These findings demonstrate that the hair-to-blood Hg ratio is a dynamic biomarker influenced by exposure intensity and potentially by Se status. hair-to-blood ratio methylmercury blood samples mercury detection human biomonitoring lasje živo srebro krvni vzorci zaznavanja živega srebra biomonitoring true false true Elsevier Nizozemska Angleški jezik Slovenski jezik © 2026 The Authors. Neznano 2026-08-04 13:54:29 2026-08-04 13:54:29 2026-08-05 03:48:58 0000-00-00 00:00:00 2026 0 0 Nasl. z nasl. zaslona; Soavtorica iz Slovenije: Milena Horvat; Opis vira z dne 27. 7. 2026; str. 1-12 Vol. 215, [article no.] 116231 Sep. 2026 0000-00-00 Zaloznikova Objavljeno NiDoloceno 2026-04-17 2026-06-19 2026-06-23 543 1873-6351 10.1016/j.fct.2026.116231 286131715 https://www.sciencedirect.com/science/article/pii/S0278691526003054 1 40d61756-8ffb-11f1-af5a-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=48842 RAZ_Cassulatti_dos_Santos_Lucas_2026.pdf RAZ_Cassulatti_dos_Santos_Lucas_2026.pdf 1 17F0BE4663C77DBC1DD189A2C6ED0189 04937cc16a5350de649b5ca17a87e2bb337fe525ce12977d107d6ddfe1c18078 9054e1be-8ffb-11f1-af5a-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=48843 Institut Jožef Stefan 0 0 0