Consumption of iodized salt doesn't give rise to thyroid-related diseases, said the disease control and prevention center in Shenzhen, as many locals have been swarming to neighboring Hong Kong to buy salt.

China issued a mandate to add iodine to salt in 1995 in a bid to prevent iodine deficiency disorders across the country.

In recent years, some people, including clinical doctors, particularly in the eastern coastal areas, detected rising thyroid-related diseases and linked that to over-consumption of iodized salt.

Epidemiology surveillance in Shenzhen showed iodized salt consumption didn't cause more cases of thyroid-related diseases and locals don't need to buy salt in Hong Kong, said an announcement by the local CDC on Thursday.

The prevalence of thyroid-related diseases has stayed at roughly 50 out of every 100,000 people for 10 years and didn't show a rising trend at all, it said.

Instead, due to the iodized salt, the prevalence of iodine deficiency disorders among local children aged 8 to 10 dropped to 1.3 percent in 2011, down from 10.8 percent in 1997, it showed.

It also helped with children's IQ development, it added.

"A rising trend of thyroid diseases has been detected in recent years, but a link between that and iodized salt use cannot be so far substantiated," said Teng Weiping, who heads the endocrine research institute of the China Medical University based in Shenyang, Liaoning province.

The Ministry of Health on Thursday issued an online notice urging local authorities to ensure the supply and consumption of iodized salt to prevent iodine deficiency disorders.

Nationwide surveillance showed that salt consumption is a major source of iodine intake among Chinese, and an end to the mandate would cause a surge in iodine deficiency disorders, it said.