Iodine Deficiency, in China
Abstract
Iodized salt is the best means of
providing iodine to deficient populations, and it
has been used successfully and safely for 70 years
around the world. In China about 450 million people
live in iodine-deficient areas. The prevalence of
endemic goitre in 7- to 14-year-old children was
estimated to be 20% (7 million cases). The Chinese
government has undertaken to eliminate
iodine-deficiency disorders by the year 2000, and
the manufacture and use of iodized salt throughout
China has been compulsory since early 1995.
Currently, potassium iodate is used. National
regulations require the iodine content of iodized
salt to be no less than 30 mg/kg in the
salt-processing plant, no less than 25 mg/kg in the
market, and no less than 20 mg/kg in the household.
According to sporadic sample checking, however, the
iodine content of salt in the market and the
household is far from satisfactory. The loss of
iodine during cooking is as high as 50% to 70%. The
major problems in the fortification of salt with
iodine in China are the use of uniodized salt in
remote areas, an unsatisfactory system for
monitoring the quality of iodized salt, the lack of
knowledge and skill among marketing staffs, the loss
of iodine during storage and cooking, and the lack
of nationwide systematic studies to monitor the
effectiveness of iodized salt in the control of
endemic goitre.
Introduction
About 1,500 million people, or nearly one-third
of the earth’s population, live in areas of iodine
deficiency. Its consequences, the iodine-deficiency
disorders, include irreversible mental retardation,
goitre, reproductive failure, increased child
mortality, and socio-economic compromise. All of
these results can be prevented by sufficient iodine
in the diet. Eliminating iodine deficiency is
recognized as one of the most achievable of the
goals that the 1990 World Summit for Children set
for the year 2000.
Iodized salt is the best means to provide iodine
to iodine-deficient populations. It is
physiological, simple, practical, and effective. It
has been used successfully and safely for over 70
years in programmes around the world. The Codex
Alimentarius standard for food-grade salt permits
the use of sodium and potassium salts of iodides and
iodates in the iodization of salt. The level of
fortification that has been used ranges from 30 to
200 ppm, which will provide enough iodine to meet
the requirement of 150 to 200 mg
per person per day [1]. In China, although iodized
salt has been commercially available for more than
40 years, it was 1995 before its use became
mandatory throughout the country.
Prevalence of iodine deficiency and
iodine-deficiency disorders in China
About 450 million people live in iodine-deficient
areas of China, and more than 30% of the total
population is at risk for iodine-deficiency
disorders. The average prevalence of endemic goitre
in children between the ages of 7 and 14 was
estimated to be 20% in 1995. All of mainland China’s
30 provinces have reported the occurrence of
iodine-deficiency disorders, primarily endemic
goitre; however, there are significant differences
in prevalence among geographic regions. There is at
least a 40-fold difference between the county with
the lowest prevalence and the county with the
highest prevalence. It is estimated that in China in
1993 and 1994, there were more than 7 million cases
of endemic goitre and more than 200,000 cases of
cretinism [2].
It is widely acknowledged that most
iodine-deficient areas are located in hilly or
mountainous regions. However, it has been uncertain
whether iodine deficiency is an issue of public
health concern in large cities in China. A recent
investigation demonstrated that subclinical iodine
deficiency (urinary iodine < 100
mg/L) was quite common in schoolchildren in
some large cities, such as Shanghai, Zhengzhou,
Hefei, and Fuzhou (table 1) [3].
Government actions to control iodine-deficiency
disorders
The Chinese government has undertaken to
eliminate iodine-deficiency disorders by the year
2000. In 1994 the Ministry of Health and the
Ministry of Light Industry jointly promulgated the
programme outlines for accomplishing this. The
strategic goals of this project are the following:
all salt for human and animal use should be iodized;
95% of the population should use iodized salt; more
than 95% of special populations (newly married
women, pregnant women, lactating mothers, infants,
and young children) should use iodine oil; and 95%
of the counties should meet the criteria for
elimination of iodine-deficiency disorders
(prevalence of endemic goitre in schoolchildren <
5%).
To ensure the mandatory nationwide use of iodized
salt, in August 1994 the State Council of the
People’s Republic of China promulgated the
Regulation on Adding Iodine to Salt to Eliminate
Health Hazards Due to Iodine Deficiency. It
stipulated that the health administration department
in the State Council shall be responsible for the
control of health hazards caused by iodine
deficiency and the health inspection and supervision
of iodized salt, and that the salt administrative
department in the State Council shall be responsible
for the manufacture and marketing of iodized salt.
According to the regulation, the mandatory
manufacture, distribution, and use of iodized salt
throughout China began on 1 October 1994 (Order No.
163 from the State Council of the People’s Republic
of China, 23 August 1994).
Effectiveness of use of iodized salt
Although the nationwide use of iodized salt was
not started until early 1995, the effectiveness of
iodized salt in the control of endemic goitre was
clearly shown in several observations and trials.
Table 2 shows the consistent reduction in the
prevalence of goitre at the provincial, city, and
county levels, where the use of iodized salt was
mandatory in every household, although no parallel
control population was available in those
observations [4-11]. However, considering the large
differences in climate, dietary patterns, cooking
habits, and other lifestyle factors among various
parts of China, the effectiveness of iodized salt in
controlling iodine-deficiency disorders needs
further studies and long-term monitoring.
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deficiency in China
