Abstract: ObjectiveTo evaluate the possible effect of environmental lead and cadmium exposure on intelligence of children aged 9-11 years in an industrial zone of Guangdong Province. MethodsA town, where the industrial zone of Guangdong Province lay, was selected as exposure area and another town adjacent to the windward side of the exposure area, as a control one. Subjects were children aged 9 to 11 years from primary schools in the two towns. IQ of the children was assessed using the Combined Raven's Test in China (CRT C2). Meanwhile, their urine levels of lead and cadmium were detected. Results Contents of lead and cadmium in urine of children in exposure area were 4.040 and 1.434 μg/L, and those in the control area, 2.136 and 1.023 μg/L, respectively (P<0.01 for both). IQ of children in the exposure area (103.38) was lower than that in the control area (106.23) (P<0.01). Multivariate logistic regression showed that urinary lead was negatively associated with children's IQ (β=-4.442，P＜0.05）, but urine cadmium was not associated with children's IQ (β=-1.277, P>0.05), after adjustment for other influencing factors. Meanwhile, no interaction was observed between urine lead and cadmium effects on IQ of the children (P>0.05).ConclusionEnvironmental heavy metal pollution has induced negative impact on children's mental development. The treatment of heavy metal pollution in the environment should be intensified to reduce the health risk caused by heavy metal exposure in children.