Study says desalination may cause iodine deficiency

Israeli researchers say that Israeli adults who consume desalinated water were found in a study to have a “surprisingly high” prevalence of inadequate iodine intake and a related thyroid dysfunction.

“Desalination is the way forward, it is a blessing,” said Dr. Aron Troen from the Hebrew University’s Institute of Biochemistry, Food Science and Nutrition, in the Robert H. Smith Faculty of Agriculture, Food and Environment in an interview. “But when you make changes that affect entire populations, you need to make sure there are no unintended consequences. Our role is to monitor that.”

A national survey should be set up to assess the iodine intake of the Israeli population, Troen said. “The consequences of not having enough iodine are serious.”

With a surging population growth and a scarcity of water worldwide, seawater desalination — in which minerals are removed from the water to make it suitable for human consumption or agriculture — is increasingly used to meet the increased demand for water.

Israel has the highest percentage of desalinated water consumption in the world, with five desalination plants producing about 50 percent of its water. An estimated 300 million people worldwide rely on over 17,000 desalination plants in 150 countries for water. And the numbers are likely to grow, according to the researchers.

Because Israel is a global pioneer in desalination, it is only natural that questions regarding the consequences on the population stem from here, Troen said.

The study took place in the city of Ashkelon on the southern Mediterranean coast of Israel, where one of the world’s largest desalination plants is located. It assessed the relationship between iodine intake and thyroid function in an area where drinking water is supplied from iodine-poor desalinated water.

In collaboration with Dr. Dov Gefel of Barzilai University Medical Center in Ashkelon and PhD student Yaniv Ovadia, the researchers used an Iodine Food Frequency Questionnaire to model the effect of depleting iodine content in drinking water on the distribution of iodine intake. Thyroid function was rigorously assessed by clinical examination, ultrasound and blood tests, including serum thyroglobulin and autoimmune antibodies.

The study found a “surprisingly high” prevalence of insufficient iodine intake and a strong association of thyroid dysfunction among adults with a low intake of iodine, the researchers said.

“The increasing reliance on desalination could contribute to an increase in iodine-deficiency disorders, which raises a nutritional and public-health issue of a major global concern,” said Troen. “This research supports the urgent need to probe the impact of desalinated water on thyroid health in Israel and elsewhere.”

Severe deficiency of iodine in mothers has been associated with miscarriages, stillbirth, congenital abnormalities in babies and also mental retardation problems, according to the American Thyroid Association. A rough calculation of the potential costs for treatment of children born in Israel if one-quarter of the population is mildly deficient amounts to 1 billion shekels — or around $265 million — a year, the researchers said.

“Luckily, any problems with iodine nutrition that might emerge from desalination can be easily and inexpensively remedied by the iodization of table salt,” Troen said. “Unlike magnesium, the solution is relatively straightforward — to iodize salt, provided there is legislation for routine population surveillance for iodine intake to ensure that salt iodization does not lead to excessive intake.”

The study was published on Public Health Nutrition.