Data are presented here on the anthropogenic I-129 inventory in regions that have been strongly affected by releases from European reprocessing facilities which, to the authors’ knowledge, presently account for > 90% of the global isotope source in the Earth’s surface environment. The results show that > 90% of the isotope inventory occurs in marine waters with the Nordic Seas and Eurasian basin of the Arctic Ocean containing most of the I-129. Within the terrestrial environment of Europe, soils contain the largest part of the isotope inventory. However, the inventory of the terrestrial system did not provide clues on the most plausible atmospheric source of I-129 to Europe, thus supply from both gaseous and marine releases is proposed. The sum of the total inventory in both the marine and terrestrial environments did not match the estimated releases. This imbalance is likely to relate to unconstrained inventory estimates for marine basins (Irish Sea, English Channel and North Sea) close to the facilities, but also to the occurrence of I-129 in the biosphere, and possible overestimated releases from the nuclear reprocessing facilities. There is no doubt that the available data on I-129 distribution in the environment are far from representative and further research is urgently needed to construct a comprehensive picture. (c) 2006 Elsevier Ltd. All rights reserved.