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

*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.

*p<0.05，
**p<0.01。
模型1：校正血铅检测时的年龄、性别、血铁水平、就读学校、父亲学历、母亲学历、父亲职业及吸烟情况。
模型2：在校正模型1的全部协变量基础上，额外纳入操作智商（PIQ）。