Radioactive releases in the environment around civilian nuclear facilities have significantly decreased over the last few decades, with the exception of tritium. In late 2007, papers published in the UK (RIFE 11 report, study by the HPA’s Advisory Group on Ionising Radiation (AGIR)) raised questions as to the behaviour of tritium in the environment. Given this context, ASN wanted to get a clear analysis of the existing studies into the issue and in early 2008 decided to establish two independent pluralistic working groups. Two main points of the discussions are on the bioaccumulation and the biological effects.