Exposure To Lead And Arsenic Related To Cognitive Effects In Children From Northern Chile

Abstract

Introduction: Neurodevelopmental effects have been reported associated to lead and arsenic exposure. Such effects have been unexplored in children living near to a remediated area contaminated with lead and arsenic in northern Chile. Objective: To determine whether high concentrations of lead in blood and arsenic in urine is associated to low intellectual quotient (IQ) performance in children. Methods: We conducted a cross-sectional study with 180 children (6 to 15 years old) who resided near a contaminated zone in Arica. Children's IQ were assessed using the Wechsler Intelligence Scale for Children, Third Edition-Chilean version (WISC-IIIv.ch). The Local Sanitary Authority provided data on children's blood lead levels (BLL) and urine arsenic concentration. Maternal IQ (WAIS-IVv.ch) and personal and family antecedents were also collected. Independent models were constructed using BLL and urine arsenic concentration as exposure variables and IQ as the main outcome adjusted by income, maternal IQ, age, sex, and birth order among siblings. Results: The median BLL and urine arsenic concentration was 2.0 g/dl (IQR 1,0 – 3,0) and 19 μg/L (IQR 12-29), respectively. 56.7% of children had IQ scores below 90 points. A non-significant inverse relationship between BLL and IQ was found (1μg/dl as reference; 2μg/dl, β -1,04 (CI95% -5,88 to 3,80); 3μg/dl, β -4,85 (CI95% -12,09 to 2,38); =4μg/dl, β 2,26 (CI95% -4,32 to 8,85). Urine arsenic concentration showed an inverse and significant relationship with IQ in children between 11 to 20 μg/L (1-10μg/L as reference; 11-20μg/L, β -7.33 (CI95% -13,20 to -1,47); 21-30μg/L, β 0.74 (CI95% -5,72 to 7,21); =30μg/L, β 2.14 (CI95% -4,37 to 8,66). Conclusions: We did not find a dose-response relationship. Possibly, due to the current biomarkers don't reflect the greater exposure occurred prior 1998, when the remedial actions began. A better estimation of chronic exposure and the comparison of IQ according to vulnerable windows are required.