Effectiveness of the European chromium(vi) directive for cement implementation on occupational allergic contact dermatitis occurrence: assessment in France and the U.K.

International audienc

Les études épidémiologiques sur les travailleurs exposés aux faibles doses de rayonnements ionisants

Purpose of the study: A review of epidemiological studies on workers exposed to low doses of ionizing radiation is proposed. Method: Workers included are radiologists and radiological technologists, miners, air flight attendants and nuclear industry workers. Studies were listed through medline data base (National Library of Medicine) without restriction on date of publication. Results: Radiologists and radiological technologists were among the first to be occupationally exposed to ionizing radiation. Excesses of leukemia, lung and skin cancer were observed for older registration years. For more recent years, epidemiological data lack sufficient statistical power to conclude. Among uranium miners, the lung cancer dose-effect relationship is well established. Effect modifiers have also been observed: decreases in the effect with time since exposure and age at exposure. An increase with the fractionation of dose is also strongly suspected. Excesses of malignant melanomas and breast cancers were observed among airflight attendants. This population is exposed to cosmic radiation, irregular working schedule and frequent jetlags. It is difficult to relate these excesses to these different factors though life-style or reproductive life factors seem to be insufficient to explain excesses of such magnitude. Finally, among nuclear workers, pathologies with more frequent dose-effect relationships are: leukemia except chronic lymphoid leukemia and multiple myeloma, the order of magnitude of excess relative risk being 2 and 4 per Sievert respectively. Lung cancer is also suspected but caution should be taken on potential confusion factors (internal radiation and other occupational factors particularly). Conclusion: This review highlights the importance of results obtained from occupational ionising radiation epidemiology. Studies should continue in order to confirm observed dose-effect relationships and better understand some of the excesses observed. It confirms the need for systematic epidemiological surveillance and post-occupational health monitoring of populations concerned. © Masson, 2005

Données épidémiologiques sur le cancer du sein radio-induit

Background. - Female breast cancer is the most frequent cancer, both in incidence and mortality. It is well known that exposure to ionizing radiation increases the risk, but some questions remain concerning low dose and low-dose rate effects and cofactors. These potential effects have to be taken into account to carry out adequate risk assessment on medically exposed populations. A literature review is proposed on this issue. Methods. - A Medline research was undertaken. Keywords used were ionizing radiation, breast cancer and epidemiology. More studies were added through references included in the first list of articles. The focus was placed on studies including quantitative dose-effect relationship analyses. Results. - A latency of five to 10 to 13 years is observed in the appearance of risk. The risk diminishes with age at exposure. A diminution with age at risk is also suspected. The excess relative risk per gray varies between 0.3 and 1.5 for an age at first exposure of 25 years. The study of Hiroshima and Nagasaki survivors shows that risk is increased even if doses are restricted to below 0.5 Gy. Above high doses (20 Gy), the risk no longer increases. This can be interpreted as a cell-killing effect. The excess subsists if doses are fractionated, but a diminution of the effect is suspected. Conclusion. - The effects of exposure to levels of doses used for medical diagnostic are very difficult to study in the general population by epidemiological methods. Only studies conducted on very young children could achieve enough power, because of their high radiosensitivity. Available information on the effects of doses above 0.5 Gy allows extrapolation on maximal effects. Models deduced from existing cohorts can be used to assess risk, with their limits due to associated uncertainties. Preston et al. proposed an excess absolute-risk model, which makes estimates from the more comprehensive cohorts compatible. This model has been retained by the 2006 committee "Biological effects of ionizing radiation" (report VII). © 2008 Elsevier Masson SAS.Position du problème Le cancer du sein est le cancer le plus fréquent chez la femme, tant en incidence qu’en mortalité. Si l’exposition aux rayonnements ionisants est un facteur de risque reconnu du cancer du sein, certaines questions ne sont pas encore résolues : quantification des effets aux faibles doses et débit de doses, influence des cofacteurs. Ces éléments sont indispensables pour mener des évaluations du risque sanitaire valides sur les populations actuellement exposées : patients, public et professionnels de santé. Nous proposons ici une synthèse de la littérature sur le sujet mettant en relief les études incluant une relation dose–effet. Méthodes Le recueil bibliographique a été réalisé à partir de la base de données « Medline ». Les mots clés utilisés étaient « rayonnements ionisants », « cancer du sein », « épidémiologie ». D’autres études ont été ajoutées grâce aux références incluses dans la première liste d’articles. Résultats Selon les études, l’excès de risque observé survient entre cinq et dix à 13 ans après la première exposition. Le risque diminue avec l’âge à l’exposition. Une diminution du risque avec l’âge au diagnostic est également suspectée. L’ordre de grandeur de l’excès de risque relatif par gray varie selon les études entre 0,2 et 1,5 pour un âge à la première exposition de 25 ans. L’étude réalisée sur les survivantes d’Hiroshima et de Nagasaki indique une augmentation du risque pour les doses inférieures à 0,5 Gy. Au-delà de 20 Gy environ, le risque atteint un plateau qui pourrait être expliqué par une augmentation de la mort cellulaire. Le fractionnement de l’exposition ne fait pas disparaître l’effet, mais une diminution de cet effet est suspectée. Conclusion Les effets de l’exposition aux rayonnements ionisants au niveau des doses délivrées actuellement dans un but diagnostic sont très difficiles à étudier par des méthodes épidémiologiques en population générale. Seuls les effets sur l’enfant en très bas âge pourraient éventuellement être abordés avec suffisamment de puissance, étant donnée la radiosensibilité des jeunes enfants. En revanche, les connaissances actuelles sur les effets des doses à partir de 0,5 Sv permettent par extrapolation d’évaluer les effets maximaux. Des modèles issus des cohortes existantes, peuvent être éventuellement utilisés pour des évaluations de risque, avec leurs limites du fait des incertitudes associées. Preston et al. proposent un modèle en excès de risque absolu, qui rend compatibles les estimations issues des principales cohortes fournissant une relation dose–effet et qui a été retenu en 2006 par le comité « Biological effects of ionizing radiation » (rapport VII)

Exposition aux radiations et mortalité chez les travailleurs du nucléaire en France

This vast cohort study covers nearly 30 000 workers at CEA and Cogema, with a mean follow-up of 17.8 years. Consistently with previous studies, it found a mortality rate lower than that of the general population. An excess risk of cancer mortality was found only for melanoma, and its association with ionizing radiation remains to be defined. As in the literature, a dose-effect relation was seen for leukemia

Exposition aux radiations et mortalité chez les travailleurs du nucléaire en France

This vast cohort study covers nearly 30 000 workers at CEA and Cogema, with a mean follow-up of 17.8 years. Consistently with previous studies, it found a mortality rate lower than that of the general population. An excess risk of cancer mortality was found only for melanoma, and its association with ionizing radiation remains to be defined. As in the literature, a dose-effect relation was seen for leukemia

CEA-EXPO: A facility exposure matrix to assess passed exposure to chemical carcinogens and radionuclides of nuclear workers

A "Facility-Exposure Matrix" (FEM) is proposed to assess exposure to chemical carcinogens and radionuclides in a cohort of nuclear workers. Exposures are to be attributed in the following way: a worker reports to an administrative unit and/or is monitored for exposure to ionising radiation in a specific workplace. These units are connected with a list of facilities for which exposure is assessed through a group of experts. The entire process of the FEM applied in one of the nuclear centres included in the study shows that the FEM is feasible: exposure durations as well as groups of correlated exposures are presented but have to be considered as possible rather than positive exposures. Considering the number of facilities to assess (330), ways to simplify the method are proposed: (i) the list of exposures will be restricted to 18 chemical products retained from an extensive bibliography study; (ii) for each of the following classes of facilities: nuclear reactors, fuel fabrication, high-activity laboratories and radiation chemistry, accelerators and irradiators, waste treatment, biology, reprocessing, fusion, occupational exposure will be deduced from the information already gathered by the initial method. Besides taking into account confusion factors in the low doses epidemiological study of nuclear workers, the matrix should help in the assessment of internal contamination and chemical exposures in the nuclear industry. © 2005 EDP Sciences