Study on the Prevalence of Thyroid Desease in Healthcare Workers at the Hospital of Pisa in Relation with Occupational Exposure to Ionizing Radiation

This study analyzes the prevalence of thyroid disease in healthcare workers who have worked at the University Hospital in Pisa. They underwent a health surveillance protocol from 2 January 2005 to 1 July 2009 with particular regard to occupational exposure to ionizing radiation. Data of health care workers were obtained by consulting Asped 2000: computerized medical records used by the University Hospital in Pisa for health surveillance of workers exposed to occupational risk. This population consisted of 6658 people: 4391 women and 2267 men. Among these, 546 people were found to have thyroid disease. Radiological exposure interested 2226 people. 213 out of 546 workers suffering from thyroid diseases were exposed to ionizing radiation. For thyroid diseases overall and for each type of thyroid disease the fraction of patients professionally exposed has been calculated. A statistical analysis was done to determine the exposure that could be a risk factor for the development of these diseases. Only for healthcare workers exposed to ionizing radiation and affected by thyroid cancer, dosimetric charts folders were collected. For thyroid diseases in general the odds ratio resulted to be 1.30 with a 95% confidence interval (CI 95%) between 1.09 and 1.55. Thyroiditis was present in 187 cases including 79 exposed subjects and 108 non-exposed subjects with an odds ratio of 1.47 (CI 95%, 1.10-1.97). No statistical significance was achieved for the other thyroid diseases analyzed (goiter, Ccell hyperplasia, hyperthyroidism, hypothyroidism, Graves' disease, nodular disease and cancer). Thyroid cancer was present in 37 cases including 14 exposed and 23 non-exposed. The odds ratio was 1.21 (CI 95%, 0.622.36). It is very important to say that the classification in exposed or non-exposed workers is not based on the real exposure to ionizing radiation but on a susceptibility of exposure, according to radioprotection principles