Drinking water is the major natural source of iodine in many European countries. In
the present study, we examined possible sites of iodine loss during the usual water
purification process. Water samples from 6 sites during the technological process
were taken and analyzed for iodine content. Under laboratory circumstances, prepared
iodine in water solution has been used as a model to test the effect of the presence
of chlorine. Samples from the purification sites revealed that in the presence of
chlorine there is a progressive loss of iodine from the water. In the chlorine concentrations
employed in the purification process, twenty four hour chlorine exposure eliminated
more than 50 % of iodine when the initial iodine concentration was 250 mug/L or less.
Iodine was completely eliminated if the starting concentration was 16 mug/L. We conclude
that chlorine used during water purification may be a major contributor to iodine
deficiency in European communities.