Table 4. Impact of blood concentrations of lead on IQ and school performance in Chinese preschool children (n = 1341).

	Blood concentrations of lead (µg/dL)
	<8.0	8.0 – <10.0	≥10.0
IQ (Model 1)
PIQ	Ref	−0.96 (−3.28, 1.36)	−1.90 (−4.89, 1.09)
VIQ	Ref	−0.48 (−3.36, 2.40)	−1.77 (−4.01, 0.46)
FIQ	Ref	−1.28 (−4.01, 1.46)	−1.45 (−3.50, 0.67)
School performance
Chinese: Model 1	Ref	−3.20 (−5.78, −0.63)*	−4.02 (−7.11, −0.93)*
Model 2	Ref	−2.67 (−5.16, 0.18)*	−3.60 (−6.58, −0.62)*
Math: Model 1	Ref	−5.25 (−8.14, −2.36)**	−5.27(−8.73, −1,81)**
Model 2	Ref	−4.46(−7.20, −1.72)**	−4.64(−7.91, −1.36)**
English: Model 1	Ref	−4.33 (−7.32, −1.34)*	−5.18 (−8.76, −1.59)**
Model 2	Ref	−3.62 (−6., −0.75)*	−4.62 (−8.05, −1.18)*

^* p<.05,

^** p<.01.

Model 1: Adjusting for age at blood lead test, sex, blood iron, school, father's education, mother's education, father's occupation and smoking.

Model 2: Adjusting covariates in model 1 plus PIQ.