Effects of lead, cadmium, arsenic, and mercury co-exposure on children's intelligence quotient in an industrialized area of southern China

• Published in: Environmental pollution (1987) Vol. 235; pp. 47 - 54
• Main Authors: Pan, Shangxia, Lin, Lifeng, Zeng, Fan, Zhang, Jianpeng, Dong, Guanghui, Yang, Boyi, Jing, You, Chen, Shejun, Zhang, Gan, Yu, Zhiqiang, Sheng, Guoying, Ma, Huimin
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.04.2018
• Subjects: Arsenic; Cadmium; Intelligence quotient scores; Lead; Mercury; Lead; Cadmium; Intelligence quotient scores; Arsenic; Mercury
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2017.12.044

Exposure to metal(loid)s can lead to adverse effects on nervous system in children. However, little is known about the possible interaction effects of simultaneous exposure to multiple metal(loid)s on children's intelligence. In addition, relationship between blood lead concentrations (<100 μg/L) and the intelligence of children over 5 years needs further epidemiological evidence. We recruited 530 children aged 9–11 years, including 266 living in a town near an industrialized area and 264 from another town in the same city in South China as a reference. The levels of lead (Pb), cadmium (Cd), arsenic (As) and mercury (Hg) in blood (BPb, BCd, BAs, BHg) and urine (UPb, UCd, UAs, UHg) were assessed, as well as children's intelligence quotient (IQ). A significant decrease in IQ scores was identified in children from the industrialized town (p < .05), who had statistically higher geometric mean concentrations of BPb, BCd, UPb, UCd and UHg (65.89, 1.93, 4.04, 1.43 and 0.37 μg/L, respectively) compared with children from the reference town (37.21, 1.07, 2.14, 1.02 and 0.30 μg/L, respectively, p < .05). After adjusting confounders, only BPb had a significant negative association with IQ (B = −0.10, 95% confidence interval: −0.15 to −0.05, p < .001), which indicated that IQ decreased 0.10 points when BPb increased 1 μg/L. Significant negative interactions between BAs and BHg, positive interaction between UPb and UCd on IQ were observed (p < .10), and BPb <100 μg/L still negatively affected IQ (p < .05). Our findings suggest that although only BPb causes a decline in children's IQ when simultaneously exposed to these four metal(loid)s at relatively low levels, interactions between metal(loid)s on children's IQ should be paid special attention, and the reference standard in China of 100 μg/L BPb for children above 5 years old should be revised. [Display omitted] •We examine interactions effects of simultaneous exposure to multiple metal(loid)s on children's IQ.•Compared with other metal exposure, BPb has stronger effects on children's IQ.•Interactions between metal(loid)s on children's IQ exist.•BPb below 100 μg/L still causes adverse effect on IQ of 9–11 years old children. When considering lead, cadmium, arsenic, and mercury co-exposure, only lead has adverse effects on children's IQ, even at blood lead level <100 μg/L. And interactions between metal(loid)s on children's IQ should be considered.