Affiliations: Department of Endocrinology and Medicine, University
Hospital Aalborg, Denmark | Institute of Food Research and Nutrition, Danish
Veterinary and Food Administration, Copenhagen, Denmark | Department of Internal Medicine I, Bispebjerg
Hospital, Copenhagen, Denmark | Centre for Preventive Medicine, Glostrup Hospital,
Copenhagen, Denmark
Note: [] Address for correspondence: Peter Laurberg, MD, Department of
Endocrinology and Medicine, University Hospital Aalborg, DK-9000 Aalborg,
Denmark. Fax: +45 98 12 02 53; E-mail: laurberg@aas.nja.dk
Abstract: Thyroid diseases are common in all populations but the type and
frequency depends on environmental factors. In Denmark geographical differences
in iodine intake are caused by different iodine contents of drinking water,
which varies from < 1 to 139 μg iodine per litre.
Comparative epidemiologic studies have demonstrated considerable differences in
type and occurrence of thyroid disease with more goitre and hyperthyroidism in
Aalborg with water iodine content around 5 μg/L, and more
hypothyroidism in Copenhagen with water iodine around
20 μg/L. In Denmark, iodine in ground water is bound in
humic substances, which have probably leached from marine sediments in the
aquifers. Interestingly, humic substances in water from other parts of the
world have goitrogenic properties, especially humic substances from coal and
shale. Humic substances are heterogeneous mixtures of naturally occurring
molecules, produced by decomposition of plant and animal tissues. The effect of
humic substances in drinking water on the epidemiology of thyroid disease
probably depends on the source of aquifer sediments.
Journal: BioFactors, vol. 19, no. 3-4, pp. 145-153, 2003
