gms | German Medical Science

50. Jahrestagung der Deutschen Gesellschaft für Medizinische Informatik, Biometrie und Epidemiologie (gmds)
12. Jahrestagung der Deutschen Arbeitsgemeinschaft für Epidemiologie (dae)

Deutsche Gesellschaft für Medizinische Informatik, Biometrie und Epidemiologie
Deutsche Arbeitsgemeinschaft für Epidemiologie

12. bis 15.09.2005, Freiburg im Breisgau

Occupational Exposure to Ionizing Radiation is Associated With Autoimmune Thyroid Disease

Meeting Abstract

  • Henry Völzke - Ernst-Moritz-Arndt-Universität, Greifswald
  • André Werner - Ernst-Moritz-Arndt-Universität, Greifswald
  • Nele Friedrich - Ernst-Moritz-Arndt-Universität, Greifswald
  • Ulrich John - Ernst-Moritz-Arndt-Universität, Greifswald
  • Wolfgang Hoffmann - Ernst-Moritz-Arndt-Universität, Greifswald

Deutsche Gesellschaft für Medizinische Informatik, Biometrie und Epidemiologie. Deutsche Arbeitsgemeinschaft für Epidemiologie. 50. Jahrestagung der Deutschen Gesellschaft für Medizinische Informatik, Biometrie und Epidemiologie (gmds), 12. Jahrestagung der Deutschen Arbeitsgemeinschaft für Epidemiologie. Freiburg im Breisgau, 12.-15.09.2005. Düsseldorf, Köln: German Medical Science; 2005. Doc05gmds091

Die elektronische Version dieses Artikels ist vollständig und ist verfügbar unter: http://www.egms.de/de/meetings/gmds2005/05gmds161.shtml

Veröffentlicht: 8. September 2005

© 2005 Völzke et al.
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Gliederung

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Context and Aims

The thyroid gland is a potential target organ for radiation-related damage. Currently, it is not clear whether occupational exposure to ionizing radiation causes autoimmune thyroid disease (AITD). The aim of the present analysis was to investigate an association between occupational exposure to ionizing radiation and AITD.

Subjects and Methods

Analyses were performed in a population-based sample of 4299 subjects who were recruited for the population-based Study of Health in Pomerania (SHIP). Among them, 160 persons reported a history of occupational exposure to ionizing radiation. AITD was defined as the combined presence of hypoechogenicity in thyroid ultrasound and antithyroxiperoxidase antibodies >200 IU/mL. Sex-stratified logistic regression analyses were performed to investigate the association of interest.

Results

Females with occupational exposure to ionizing radiation had more often AITD than non-exposed females (10.0% vs. 3.4%, p<0.05). This association persisted after adjustment for relevant confounders (odds ratio [OR] 3.46, 95%-confidence interval [95%-CI] 1.16; 10.31, p<0.05). In males, there were too few subjects who fulfilled the criteria of AITD, but the association between the exposure to radiation and hypoechogenicity of the thyroid gland barely missed statistical significance (OR 2.20, 95%-CI 0.92; 5.26, p=0.08). In both females and males, subjects with a length of exposure of >5 years exhibited the highest risk of the endpoints.

Discussion

From our data we can only speculate about the nature of AITD as a potential radiation effect. While further studies are clearly indicated to assess the mechanisms and whether a specific type of radiation exposure is responsible for AITD, radiation protection practice should adopt the precautionary principle. Thus, damage of the thyroid gland by external radiation can effectively be reduced by using thyroid protection shields and further protection devices. As to the results of the present study, the usage of thyroid protection shields by radiation workers in order to prevent AITD should be recommended.

Limitations include the relatively low number of exposed persons and the lack of detailed information on lifetime radiation exposure. The risk estimation for the association between the exposure to radiation and AITD, however, was precise, consistent over a number sensitivity analyses, and not seriously affected by different categorizations of confounding risk factors. We were also able to demonstrate a dose-dependent relation between the duration of the exposure and AITD among both females and males. However, since the dose rate which exposed people may have varied, the duration of exposure is only a proxy of the radiation dose and cannot substitute a more accurate measure of the exposure in further studies. While a cross-sectional study like the present is generally not suitable to establish causal relations, the latter points and the given biological plausibility may indicate such causality. Additional case-control studies are, however, needed to confirm the present findings, and cohort studies should be designed to investigate possible causal relations.

Conclusions

Occupational exposure to ionizing radiation is related to the risk of autoimmune thyroid disease. While confirmation of a causal relation is pending, the use of thyroid protection shields by radiation workers is strongly recommended based on the precautionary principle.

Acknowledgement

The work is part of the Community Medicine Research (CMR) net of the University of Greifswald, Germany, which is funded by the Federal Ministry of Education and Research (grant no. ZZ9603), the Ministry of Cultural Affairs as well as the Social Ministry of the Federal State of Mecklenburg-West Pomerania. The CMR encompasses several research projects which share data from the population-based Study of Health in Pomerania (SHIP; http://www.medizin.uni-greifswald.de/cm/).