Chennai: Tamil Nadu is India’s second-largest salt producer, but it had the lowest share of households using adequately iodised salt among all states in the latest survey the state cites, health minister K G Arunraj said on Monday at an event organised for the iodine deficiency disorders prevention day at Justice Basheer Ahmed Sayeed College for Women.The 2018-19 India iodine survey found that only 62% of Tamil Nadu households used adequately iodised salt, against a national average of 76%. “We cannot accept iodine deficiency in the land that produces the salt,” he said. Many families buy loose, unbranded rock salt, store it in open containers exposed to sun and moisture, and add salt early in cooking and boil it for long, which lets the iodine escape, Arunraj said. A recent study by a city-based medical institution found that rural residents eat about 13 g of salt a day and a third of households use salt with too little iodine.Iodine is a trace mineral, needed in tiny amounts, that the body cannot make. The thyroid gland uses it to produce hormones that govern growth and metabolism, and that guide the developing brain, said director of public health Dr A Somasundaram. The stakes are highest in pregnancy, when a fetus depends entirely on its mother’s supply. Severe shortages can cause goitre, miscarriage, stillbirth and lasting intellectual impairment in children. Even mild deficiency has been linked to lower verbal scores and weaker reading skills.WHO says iodine deficiency is the leading preventable cause of brain damage, Arunraj said, adding that studies show children in iodine-deficient communities score 10 to 15 IQ points lower on average. The public health department tests schoolchildren for goitre in every district. Data released in parts by the department on Monday showed goitre in 9% of schoolchildren screened in Ramanathapuram in 2024-25. Villupuram recorded about the same share, 9%, in 2018-19. Madurai reported 6% in 2022-23, and Pudukottai recorded 5% in 2024-25. All these districts, officials said, are considered high risk for goitre.Under food safety rules, salt for human consumption must contain 30mg of iodine per kg at the production stage and at least 15mg per kg at the household level. Village health nurses test cooking salt in homes. In sample analysis done between April 2025 and March 2026, the percentage of adequately iodised salt varied between 70% and 88% in districts including Thanjavur, Tirunelveli, Virudhunagar(Sivakasi), Kallakurichi, Thoothukudi and Tiruvarur. At least 2% of salt in Thoothukudi, land of salt pans, tested with nil iodine content.The health minister said the food safety department initiates action against manufacturers for violations. “This action will continue with greater intensity,” he said. The state runs a campaign to reduce salt intake, aimed at preventing hypertension, heart disease, stroke and kidney damage, he said. “It means we must use less than 5g a day, but only iodised salt,” he added.
