Goiter prevalence and bacterial contamination of water supplies.

Previous epidemiological studies have shown a significant statistical correlation (P < 0.005 to P < 0.0005) between goiter prevalence and rock types in the watersheds that supply 37 localities in Western Columbia. Bacterial contamination has also been implicated as a cause of endemic goiter. We, therefore, did bacteriological studies to incorporate this variable into the statistical model in 34 of the 37 localities previously surveyed. Samples of the water in the 34 localities were taken at the water source or intake of water supply and at the pipeline system in households and schools. Samples were collected in sterile bottles and cultured on several media for 48 h. The number of bacteria per ml was determined by Quebec's camera and the bacteria (E. coli, Bacillus sp., K. pneumoniae, Proteus sp., and Neisseria sp.) were identified according to conventional methods. Multiple regression analysis and the logistic regression model were used to analyze the data. Only two variables had significant relationships with goiter prevalence: K. pneumoniae in the water source (P < 0.01) is related to a lower prevalence and the overall concentration of bacteria in the pipeline system (P < 0.05) is related to a higher prevalence. Multiple regression analysis to compare the effects of bacteriological variables to those of geological variables indicating rock types showed sedimentary rocks in the watershed associated (P < 0.005) with higher goiter prevalence and an increased concentration of K. pneumoniae in the water source again associated (P < 0.025) with lower goiter prevalence. Bacterial concentration in the pipeline system was of marginal importance (0.05 < P < 0.10). Thus, the presence of sedimentary rocks was the best indicator of disease. A second best indicator was the concentration of K. pneumoniae in the water source. We hypothesize that the lower goiter prevalence associated with K. pneumoniae may be a natural example of biodegradation of the organic contaminants that produce goiter.

Geologic implications in the distribution of endemic goiter in Colombia, South America.

A survey of 37 communities supplied by stream water and receiving iodised salt for the last 10-20 years indicates that the presence of sedimentary rocks in the watersheds of streams more closely correlates with goiter prevalence than 12 other possible causative variables. These results support the hypothesis that sedimentary rocks rich in organic matter are the main source of water-borne goitrogens.

Epidemiology of endemic goitre in western Colombia.

This paper reports on recent epidemiological observations in western Colombia, which further demonstrate the presence of naturally-occurring goitrogens contaminating water supplies in areas where goitre persists despite prolonged and continuous iodine supplementation. 'Prospective' and 'cross-sectional' studies in 41 localities where the populations have been on a uniform and adequate iodine supplementation for the last 10-20 years indicate that, in the endemia of western Colombia, environmental factors other than nutritional iodine deficiency are responsible for differences in goitre prevalence. Further epidemiological studies to determine the causal factors for the persistence of the endemia established a correlation between the sources of drinking water and goitre prevalence rates. Organic compounds containing sulfur with marked thionamide-like antithyroid activity were isolated from water supplying endemic goitre districts, and results are presented supporting the hypothesis that sedimentary rocks rich in organic matter are the main source of water-borne goitrogens. Bacteriological investigations showed that the presence of Klebsiella pneumoniae in drinking water and bacterial concentration were related significantly with goitre prevalence only in the presence of other variables, particularly the presence of sedimentary rocks. In the light of these epidemiological observations and experimental studies it may be concluded that, at present, endemic goitre in western Colombia is not due to nutritional iodine deficiency, but that water supplies are contaminated with sulfur-bearing organic compounds with thionamide-like antithyroid activity most probably deriving from sedimentary rocks rich in organic matter and that these compounds are the main factor underlying the endemia.