A review of internal exposure accidents

The definition of an internal exposure accident is much more difficult to establish clearly than the one concerning external overexposures. For the latter, the notion is implicitly related to resulting health damage, while in most cases any internal contamination, regardless of its level and the upcoming or no of a detriment, is qualified as accidental. Therefore, this overview is limited to (1) large scale internal exposure accidents because large groups of individuals, highly contaminated or not, were involved; (2) occupational contaminations which sometimes resulted into long-term health effects, and (3) the results of the follow-up of patients who were either explored or treated in the 30s and 50s by alpha emitting radionuclides. Among large-scale accidents, mention is made of the 1954 american nuclear test in the Pacific ocean, uncorrectly programmed and responsible for thyroid diseases, of the 1957 accident in the Mayak complex in the Urals, of the Chernobyl nuclear reactor accident in 1986 and of the 1987 Goiania accident due to the uncontrolled dismantling of a teletherapy source. Among occupational contaminations, several medical and epidemiological follows-up are of particular interest, such as those concerning dial painters who used radium in the years 1910 and uranium miners, although it is difficult to qualify as accidental these practices, even if the doses received at this time were widely in excess of the limits in use nowadays. Taking into account the previous caution, the groups of patients who received relatively large amounts of thorotrast (used as contrast material) and of radium (considered as a large spectrum therapeutic agent) are very interesting as well; these two medical practices resulted into various long-term health effects, and were used, in some degree, to quantify the risk in man of alpha emitters. (author)