The iodine level in table salt will be decreased, said the Ministry of Health.

According to the ministry, nearly 31 million people scattered across six provinces and areas including Shandong, Hebei, and Jiangsu, had abnormal levels of the chemical element.

However, the latest reports from the ministry showed that the level of iodine was normal for the majority of the nation's population.

"It's the fourth time that China has adjusted the iodine level in table salt since a national compulsory iodization of salt began in 1995 to improve public health," said Li Quanle, director of the endemic control department under MOH.

He declined to give the exact date when people will be able to buy the new salt on the market, which experts say might be in late 2010.

"The salt sold now is still safe for the people," he told China Daily yesterday.

Early independent reports stated that too much iodine over a long period leads to hyperthyroid-related diseases, particularly in iodine-rich regions such as the coastal provinces. Seafood, for example, is rich in iodine.

MOH denounced the allegation in the reports, citing multiple causes for such illnesses such as pollution, pressure and changing lifestyles. The ministry said there was a lack of scientific evidence to link iodine with hypothyroid-related diseases.

As of October 2008, more than 91 percent of the entire population in iodine-rich areas could only get common iodine-less salt at local markets, Li said.

Sites were set up across the nation in 1995 to regularly monitor salt iodine levels, conduct occasional health surveys on goiter and measure iodine in the urine among people in the iodine-saturated areas.

"It's so important for health authorities to monitor iodine levels and the adequacy of iodine levels in salt and adjust salt iodine levels based on monitoring results," said Vivian Tan, press officer of World Health Organization Beijing office.

The Chinese government has promoted iodized salt since 1995, mainly to address the iodine deficiency in 700 million people in China. A deficiency can lead to illnesses such as endemic goiter and mental retardation.

As of 2002, the iodized salt was distributed to 95 percent of China, which has helped improve general IQ of Chinese children by 12 percent and lower their incidence of goiter by 15 percent, MOH statistics show.

"The policy also means people from then on could hardly buy common salt on the market for quite long," said Cui Gonghao, professor with the Medical School of Zhejiang University.

"That might pose health risks for people who have enough iodine from diet rich in seafood, another major source for iodine," he said.

He suggested the government abolish the current carpet ban of common salt, which is cheaper than salt fortified with iodine.

People should be allowed to choose between iodized salt and common salt, urged some experts.

In fact, MOH has issued tips for the public about how to properly choose salt, said Hao Yang, deputy director of the ministry's disease control and prevention bureau.

For instance, nodular goiter patients should use common salt, which could be bought with a doctor's prescription at designated stores.

The average daily intake of iodine for the Chinese today is between 150 and 300 microgramme, within the 300-microgramme ceiling set by the WHO.

Source: China Daily