Salt: an ineffective vehicle for iodine delivery to young children in rural Sarawak

The urinary iodine excretions of women (15-40 y) and young children (< or = 6 y) from two longhouse villages in the iodine-deficient district of Lubok Antu, Sarawak, were compared. One longhouse (Mengkak) was provided with freshly produced iodized salt every two months (one kg per family) while the other (Menjiling) was provided with iodized water via fortification of the village piped-water supply. Spot urines were collected for iodine determination at baseline and at 6 and 12 months after the start of the study. Salt and water samples were collected at monthly intervals. Goiter assessment was performed on the women at the start and end of the one-year study. The mean iodine concentrations in the salt samples from Mengkak and Menjiling were, respectively, 47.1 +/- 9.7 mg/kg (n = 60) and 0.8 +/- 3.4 mg/kg (n = 60) while the mean iodine concentration in the water samples from Menjiling was 138.6 +/- 43.2 micrograms/L (n = 24); iodine could not be detected in the water samples from Mengkak. There were significant and sustained increases in median urinary iodine excretions of both women and young children in Menjiling; in Mengkak, however, significant and sustained increases in median urinary iodine excretions were observed only in women while the median urinary iodine excretions of children remained essentially unchanged throughout the study period. Goiter prevalences in the women were reduced in both longhouses. The above observations reveal the inadequacy of iodized salt as a vehicle for iodine delivery to young rural Sarawakian children and indicate the need for other means of delivering supplemental iodine to this age group in areas where salt iodization is the only strategy for IDD control. In contrast, iodization of village water supply by itself is adequate in delivering iodine uniformly to the whole community.