From naturally occurring goitrogens to the effects of anthropogenic endocrine disruptors on the thyroid in Slovakia.

The objective is to describe the effect of mandatory and well monitored prophylaxis of endemic goitre in Slovakia with the use of iodised salt for past 50 years and previous experimental attempts to assess a possible participation of naturally occurring goitrogens in the etiology of goitre. Previous observations by others showed a striking decrease of goitre prevalence in schoolchildren as early as few years after starting the prophylaxis in Slovakia and this success has been confirmed by a European study conducted by others in mid nineties. In the meantime, however, massive industrialisation of Slovakia and environmental negligence of the administration resulted in heavy airborne and mainly waterborne pollution of the food chain in certain areas around large chemical factories by industrial waste including polychlorinated biphenyls (PCB). Since Slovakia has been recently evaluated as an iodine replete country as based on the findings of the low thyroid volume by ultrasound and high urinary iodine, it became possible to evaluate the participation of factors different from iodine deficiency in the thyroid growth. Recent field surveys including an extensive international study PCBRISK repeatedly showed highly increased blood PCB level in subjects living in the polluted area and, at the same time, increased thyroid volume by ultrasound, increased frequency of positive thyroid antibodies and impaired glucose tolerance. (Ref. 59)