Progress in salt iodization and improved iodine nutrition in China, 1995--99

In 1993, the State Council of China announced the policy to virtually eliminate iodine-deficiency disorders (IDD) by 2000 and adopted universal salt iodization (USI) as the national strategy. Biennial province-based monitoring from 1995 onward aimed at capturing the use and iodine content of household salt, along with urinary iodine concentrations among schoolchildren from the same households. This paper reports on the progress made in China toward the goal of virtually eliminating iodine-deficiency disorders on the basis of 85 population-representative surveys in China's provinces during 1995--99. The percentage of households using adequately iodized salt (iodine > or = 20 mg/kg) increased from 43.1 % in 1995, to 82.2% in 1997, to 89.0% in 1999. In 1999, at least 90% of the households in 15 (48%) of the 31 provinces used adequately iodized salt, and a median urinary iodine concentration of less than 100 microg/L in children was reported in only one province. Across provinces, the median urinary iodine concentrations in children were positively correlated in each survey year with the median household salt iodine contents (combined r(s) = 0.74, p < .001) and with the proportions of households using adequately iodized salt (combined r(s) = 0.81, p <.001). Also in each survey year, the percentage of children with urinary iodine concentrations of at least 300 microg/L was correlated (combined r(s) = 0.69, p < .001) with the proportion of households using salt with iodine content of at least 40 mg/kg. The median urinary iodine concentration in children had reached 300 microg/L or more in 13 provinces (42%) by 1999. In a little more than five years, then, China has achieved outstanding progress toward the goal of virtual elimination of IDD through USI. Policy recommendations include improvement of quality assurance by salt manufacturers, along with a modest reduction in the mandated salt iodization levels.