Endemic goiter in western Colombia.

Goiter continues to occur in some areas of western Colombia despite iodine supplementation for 30 years. In 1973-1977, an average goiter prevalence of 15% (range 1-42%) still persisted among schoolchildren of 41 localities. Significant relationships were found between goiter prevalence and both the geological composition of watersheds and bacterial contamination of water supplies. Together, these associations account for 80% of the observed variation in goiter prevalence. The presence of sedimentary rocks rich in organic matter (coals, shales, etc.) was the best indicator of disease. The second best indicator, presence of K. pneumoniae in the water source, was associated with lower goiter prevalence but, as in other investigations, contamination of the pipeline system (households and schools) with gram-negative bacteria was associated with higher disease rates. Thus, epidemiological evidence indicates a cause-effect relationship between sources of drinking water and the persistence and development of goiter in this part of the world. Furthermore, identification of resorcinol, phthalate esters, and sulfur-bearing organic compounds, possibly aliphatic disulfides, in the water supplying the endemic goiter district of Candelaria town in western Colombia adds experimental support to this hypothesis. Resorcinol is derived from coal and humic substances, high molecular weight complex polymeric organic compounds present in sedimentary rocks, soils and water. Resorcinol is goitrogenic in man and experimental animals. Phthalate esters, also related to humic materials, undergo biodegradation by gram-negative bacteria with production of intermediate metabolites possessing antithyroid activity. Like phthalates and resorcinol, organic disulfides have also been identified as water contaminants in other parts of the world, and are known to be potent antithyroid compounds. The goitrogenic effect of organic and bacterial pollutants in water supplies is more pronounced in segments of the population with dietary iodine deficiency--as seen prior to the iodine prophylaxis program--and/or poor socio-economic conditions. Studies are underway to provide both insight into the biogeochemical cycle of water-borne goitrogens and knowledge essential to the development of rapid, inexpensive, and precise methods for detecting and quantifying the offending agents, as well as devising effective sanitation techniques for their inactivation and/or elimination. The impact of such measures will be determined on goiter prevalence and other parameters of health and nutrition of the communities under study.(ABSTRACT TRUNCATED AT 400 WORDS)