Cutaneous penetration and permeation of tritiated particles: Experimental evidence from the TITANS EU project

During nuclear facility decommissioning, the release of tritiated particulate matter from contaminated stainless steel and cement poses potential dermal exposure risks for workers and nearby environments. This study investigates the transdermal behavior of tritium (3H) released from tritiated stainless steel (TSSPs) and cement particles (TCPs), two matrices differing in physicochemical composition and hydrogen-binding properties. Using in vitro Franz diffusion cells and excised human skin, 3H permeation was evaluated under intact, damaged, abraded, and decontaminated skin conditions. Intact skin provided an effective barrier, whereas compromised epidermal integrity markedly enhanced 3H diffusion and retention. Differences in 3H release kinetics between particle types were associated with their surface characteristics and mechanisms of 3H binding, solid-solution entrapment in TSSPs versus isotopic exchange and surface adsorption in TCPs. The persistence of 3H within partially damaged skin suggests potential formation of organically bound tritium (OBT), indicating localized and sustained radiobiological exposure. Importantly, simple water decontamination significantly reduced 3H permeation, supporting its practical relevance in occupational dermal protection. These findings provide insight into the material interactions and dermal safety implications of tritiated particulates, contributing to risk assessment strategies in radiological and material exposure contexts.