Excessive iodine in iodized household salt in Nepal

Iodine is an essential trace element required for the regulation of physiological processes involving the thyroid gland. However, inadequate and excessive intake of iodine are responsible for health problems, such as iodine deficiency disorders, hypothyroidism, hyperthyroidism, thyroiditis, thyroid papillary cancer, and thyrotoxicosis. The Universal Salt Iodization (USI) program has become successful in providing supplemental iodine at the population level globally. Packaging quality, fortification level, and transportation and storage conditions of iodized salt determine the availability of iodine. Previous studies have reported severe health issues caused by excessive iodine intake after the implementation of the USI program. To understand the levels of iodine, we collected 2117 household salt samples from seven districts of Nepal and tested them for iodine content; among them, 98.1% were iodized. Overall median concentration of iodine was 53.9 ppm (range: 43.5-61.4 ppm). The majority (67.2%) of samples had iodine in the range of 45-75 ppm. Approximately 0.9% of samples had inadequate, 13.3% contained adequate, and 83.9% had excessive iodine than the World Health Organization-recommended value. Iodine content varied among the sampling districts and seasons, to some extent. Our study confirmed that iodized salt is widely used in Nepal and is excessively iodized. Excessive intake of iodine through iodized salt requires further attention by policy makers. The iodine level may need adjustment to address the health impact.