New Delhi, Sept. 13: A group of public health experts has questioned the rationale for universal salt iodisation in India, arguing that the prevalence of iodine deficiency appears to have been overestimated.

The experts from the Jawaharlal Nehru University, New Delhi, the Christian Medical College, Vellore, and non-government health organisations have said available studies provide only “weak evidence” to support universal salt iodisation in India.

In a letter sent to the health ministry, they have sought a scientific debate on universal salt iodisation. The government is currently on the verge of reimposing a ban on the sale of non-iodised salt for human consumption.

Proponents of salt iodisation have rejected the claims. They warned that without universal salt iodisation, tens of thousands of children and unborn foetuses across India will be at the risk of developing preventable brain damage.

“There is sound scientific evidence in favour of universal salt iodisation,” said Dr Chandrakant Pandav, the head of community medicine at the All India Institute of Medical Sciences.

A senior nutrition scientist said more than 98 countries have introduced universal iodisation of salt. “It is an absolutely safe and cost-effective measure to prevent iodine deficiency disorders,” said Dr Umesh Kapil, a nutritionist at the AIIMS.

Iodine deficiency has long been recognised as the most important factor for preventable mental retardation and cretinism among children. It often shows up as goitre, a swollen thyroid gland, in iodine deficient areas.

To iodise edible salt, the Centre had first banned the sale of non-iodised salt in 1986. But the previous government had in September 2000 revoked the ban. Now, after persuasion by the medical community, the present government issued a notification declaring its intention to ban non-iodised salt.

In their letter, the experts from JNU and CMC have said studies in some areas indicate that goitre has declined despite little use of iodised salt while, in other areas, high use of iodised salt has had little impact.

“Salt iodisation is made out to be an inexpensive solution, but we’re asking whether the magnitude of iodine deficiency in India truly justifies universal salt iodisation and its possible negative health consequences,” said Dr Ritu Priya at the Centre of Social Medicine and Community Health, JNU, who is among more than 200 signatories to the letter.

They have acknowledged that iodine deficiency is likely to be a public health problem in many areas of the country. “In such places, it is important to subsidise iodised salt and promote it aggressively,” said Dr Anant Phadke with the Centre for Enquiry into Health and Allied Themes in Pune. “But suppose just 400 million people are at risk of iodine deficiency, why ask our entire one billion to consume iodised salt?” he asked.

“I think a debate on this is justified,” said Dr Nihal Thomas, the head of endocrinology at the Vellore college, who was not a signatory to the letter. “There have been concerns among endocrinologists that salt iodisation may precipitate symptoms in patients with auto-immune thyroid disorders.”

A report compiled by the Indian Council of Medical Research (ICMR) last year had said 253 districts out of 310 surveyed by the health ministry were endemic or high-risk zones for iodine deficiency disorders. A survey between 2000 and 2004 in many states had also revealed that iodine deficiency is widespread in India.

In their letter, the experts have also asked the health ministry why it has not made public its district-level data that is often used to justify the universal iodisation of salt. Ritu Priya said a recent ICMR survey shows that there is no correlation between iodised salt intake and goitre levels.

The study had shown that Dehra Dun had 30 per cent goitre prevalence among children but salt iodisation was 80 per cent. On the other hand, Mehboobnagar had 13 per cent goitre rate, but its salt iodisation level was just 5 per cent.

“It’s unethical for experts to highlight only the benefits of universal iodisation and hide its negative health consequences,” said Ritu Priya.