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Study of the possible toxicity of tungsten particles emitted by Iter

​CEA researchers and their partners have synthesized and characterized tungsten particles similar to those to be produced by the Iter fusion reactor and have identified their cyto-genotoxic properties in lung models.

Published on 29 January 2020

​The International Thermonuclear Experimental Reactor (Iter) aims to produce carbon-free energy through thermonuclear fusion. Nuclear fusion reactions create tritiated tungsten particles, the hazard of which remains to be established in order to implement effective prevention strategies against the risk of occupational exposure in the event of loss of containment. To anticipate this health issue, this consortium of researchers from various backgrounds produced 'Iter-like' particles as close as possible to those that should be generated within Iter, then studied (i) their physico-chemical characteristics, (ii) their behaviour in a biological environment and (iii) their potential toxicity.

These particles were produced by various techniques (planetary milling, laser and plasma ablation), then characterized and loaded with tritium. The work showed that the physico-chemical stability of the particles generated varied according to the biological host environment, which made it possible to define in particular the kinetics and mechanisms of the oxidative dissolution of tungsten.

Since inhalation is the principal route of exposure, two biological models representative of the human lung were used. In an in vitro 3D cell model of human lung epithelium, no significant toxicity was observed over 28 days following 24-hour exposure to Iter-like particles. In contrast, single-stranded DNA breaks and chromosomal damage were found in a lung cell line. The researchers demonstrated that the genotoxic effects observed were not due to the presence of tritium in the particles, but rather to the release of soluble tungsten by oxidative dissolution. Since genotoxicity is likely to initiate a carcinogenic process, in vivo studies should be considered to determine the mutagenic potential of these particles.

This work was carried out within the transdisciplinary project A*MIDEX/PASSIV-Iter which brings together several CEA Institutes (Biam, Iramis, IRFM, Institut Frédéric-Joliot) as well as researchers from Aix Marseille University and CNRS (CEREGE, IMBE, LP3, LAMES, LSPM) and the INFLPR in Bucharest.

Scanning electron microscopy photography of Iter-like particles produced by plasma erosion of a tungsten target. © INFLPR

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