As measured by the rural version of the Chinese Standardized Raven Test, the average IQ of 320 children conceived and raised in the village of Biji, Linyi County, Shanxi Province, with 4.55 mg F/L in the drinking water, was 100.24±14.52. The average IQ of the same number of children conceived and raised in the control village of Jiaobei in the same county with 0.89 mg F/L in the drinking water was significantly higher at 104.03±14.96 (p<0.01). Higher rates of dental and skeletal fluorosis were found in Biji than in Jiaobei. Although the two villages have essentially the same cultural, occupational, health care, and life-style characteristics, higher IQs of the children were associated with higher levels of parental employment and education.
Translated by Julian Brooke for Fluoride Action Network and published with the concurrence of the Chinese Journal of Control of Endemic Diseases 1991;6 Suppl:99-100 in the journal Fluoride.
Distribution of intellectual ability in the endemic area and the control:
The IQs of most of the 7–14 year old children from both the endemic area and the control area were in the average or above average range, but among the 320 children in the high fluoride area there were two children, or 0.60%, whose IQ was lower than 69, which classifies them as being intellectually underdeveloped. There are no children from the control group that fall into the intellectually underdeveloped range. In the endemic area, children in the excellent or outstanding range make up 9% of all the children tested, whereas in the control area 15% of the children are classified as excellent or outstanding (see Table 2).