Bioavailability of iodine and hardness (magnesium and calcium salt) in drinking water in the etiology of endemic goitre in Sundarban delta of West Bengal (India).

Endemic goitre has been reported from the ecologically diverse Sundarban delta of West Bengal (India). To study the etiological factors for the persistence of endemic goitre, bioavailability of iodine and hardness of water used for drinking in the region were evaluated because these common environmental factors are inversely and directly related with goitre prevalence in several geographical regions. For the present study from 19 Community Development Blocks of Sundarban delta, 19 areas were selected at random. From each area at least 8 drinking water samples were collected and analyzed for iodine and the hardness (calcium and magnesium salt content). Iodine content in the drinking water samples was found in the range from 21 to 119 mg/L and total hardness of drinking water was found to range from 50 to 480 ppm. Presence of magnesium salt was found higher than the calcium salts in most of the samples. These findings suggest that the entire delta region is environmentally iodine sufficient but water is relatively hard and thus possibility of hardness of water for the persistence of endemic goitre may not be ruled out.

Iodine nutritional status of children in North East India.

OBJECTIVE: To assess the iodine nutritional status of school children in selected areas of Imphal West District of Manipur where endemic goitre and associated iodine deficiency disorders (IDD) are prevalent in the post-salt iodization period. METHODS: A total of 961 school children in the age group 6-12 yrs of both sexes were clinically examined for goiter from three study areas- one from rural block and two from urban areas. One hundred twenty urine samples were analysed for iodine and thiocyanate respectively. One hundred and five edible salt samples were also collected from the households to evaluate the iodine content. Drinking water samples from different sources were collected and iodine level was analysed to study the bioavailability of iodine in the region. RESULTS: The total goiter rate was 34.96% (Grade 1- 32.15%; Grade 2- 2.81%) showing that IDD is a severe public health problem. The median urinary iodine levels in the studied areas were in the ranges from 12.5-17.5 microg/dl indicating no biochemical iodine deficiency in the region. Mean urinary thiocyanate level was 0.839+/-0.33 mg/dl showing that the people consume sufficient foods containing thiocyanate precursors. About 82% salt samples had iodine level more than 30 ppm and the iodine content in salt samples less than 15 ppm was only about 3% indicating the salt samples at house hold contain adequate iodine. CONCLUSION: Iodine content in drinking water samples ranged from 1.8-2.6 microg/l showing that the studied region is environmentally iodine deficient. Inspite of the consumption of adequate iodine, the existing goiter prevalence among school children during post salt iodization phase ensures that environmental factors other than iodine deficiency may have the possible role in the persistence of endemic goiter in the population. The role of thiocyanate in this regard may not be ruled out.

Iodine nutritional status & prevalence of goitre in Sundarban delta of South 24-Parganas, West Bengal.

BACKGROUND & OBJECTIVE: In post salt iodization phase endemic goitre and associated iodine deficiency disorders (IDD) were found prevalent in a randomly selected rural area of Sundarban delta and its adjoining areas of West Bengal. The present investigation was thus undertaken to study the total goitre rate, urinary iodine and thiocyanate excretion pattern of the school going children, iodine content in edible salt and drinking water in the Sundarban delta of South 24-Parganas in West Bengal. METHODS: A total of 4656 school children (6-12 yr) were clinically examined for goitre from 13 different areas in the delta region. Urinary iodine and thiocyanate levels were measured in 520 (40 from each area) samples collected randomly to evaluate the iodine nutritional status and consumption pattern of dietary goitrogen. Simultaneously iodine content was determined in 104 (8 from each area) drinking water samples and 455 (35 from each area) edible salt samples collected from the areas. RESULTS: Children of all the areas were affected by endemic goitre. The prevalence rates were in the ranges from 25-61 per cent; overall goitre prevalence was 38.2 per cent (grade 1--34.0%; grade 2--4.2%). Median urinary iodine level in the studied areas was 225 microg/l (range 115-525 microg/l) indicating no biochemical iodine deficiency in the region. Mean urinary thiocyanate levels were in the range from 0.326-1.004 mg/dl. Iodine content in drinking water samples were in the ranges from 22-119 microg/l, and 55.6 per cent edible salt samples had iodine level above the recommended 15 ppm at the consumption point. INTERPRETATION & CONCLUSION: The severity of endemic goitre was high in the studied population though the iodine nutritional status was found satisfactory in the region indicating no biochemical iodine deficiency. The people of the region consumed iodine through iodized salt but about 44 per cent of the salt samples at household level contained inadequate iodine, however their iodine intake was compensated through iodine in water and food. They also consumed dietary goitrogen. Environmental factors other than iodine deficiency may have possible role for the persistence of endemic goitre in the region. More investigations are thus necessary to arrive at certain definite cause of high goitre rates in this population.