Table 3.
Distribution of children 8 –12 years of age based on intellectual function.
| Distribution (%)
|
||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Group | na | Age in years (mean ± SD) | IQ (mean ± SD) | ≤ 69 | 70–79 | 80–89 | 90–109 | 110–119 | 120–129 | ≥ 130 |
| High-As | 180 | 9.9 ± 1.5 | 95.1 ± 16.6* | 8.3 | 9.4 | 13.3 | 49.4 | 15.6 | 2.8 | 1.1 |
| Medium-As | 91 | 9.8 ± 1.4 | 100.6 ± 15.6** | 3.3 | 6.6 | 11.0 | 49.5 | 17.6 | 9.9 | 2.2 |
| High-fluoride | 253 | 9.9 ± 1.4 | 100.5 ± 15.8** | 4.0 | 5.9 | 12.3 | 48.2 | 22.9 | 4.7 | 2.0 |
| Control | 196 | 9.9 ± 1.5 | 104.8 ± 14.7 | 0 | 7.7 | 7.7 | 44.4 | 24.5 | 12.8 | 3.1 |
| Shanxi | 1,274 | 9.0 ± 0.82 | 108.0 ± 14.0b | 1.3 | 2.0 | 5.7 | 44.8 | 25.4 | 16.0 | 4.7 |
| China | 37,288 | 9.0 ± 0.94 | 103.5 ± 17.7c | 3.6 | 5.4 | 10.5 | 43.1 | 19.8 | 12.6 | 5.0 |
a
Number of children tested.
b
The average IQ of children in Shanxi was determined to be 108.0 ± 14.0 in 2005, which is statistically different from that of the control group (u = 3.2, p < 0.01).
c
The average IQ of Chinese children was determined to be 103.5 ± 17.7 in 2005, which is not statistically different from that of the control group (u = 0.996, p > 0.05).
Significant difference from control group:
*
p < 0.01,
**
p < 0.05.