Neurocognitive Status of Andean Children with Chronic Environmental Lead Exposure

Abstract

S. Allen Counter, Leo H. Buchanan, Fernando Ortega

Aim: Chronic lead (Pb) exposure has been associated with neurocognitive impairment in children and adults, including deficits in attention, intelligence, memory, executive functions and behavior. Pediatric Pb exposure results in poor performance on neurocognitive tests that may be irreversible. The aim of the present study was to assess the long-term neurocognitive status of children with a history of chronic and high environmental Pb exposure. Methods: Pb exposure over time was determined by measurements of blood Pb levels (PbB) at two different test periods. Raven Coloured Progressive Matrices (RCPM) and the Digit Span test of auditory memory/attention were used to measure neurocognitive functioning. The study group of 28 Ecuadorian Andean children ranged in age from 4.8 to 15 years. Results: The mean PbB level of the children at the time of the first RCPM test was 49.3 μg/dL (SD: 30.1; range: 4.4-119.1), and indicative of Pb poisoning. The mean PbB level at the time of the second RCPM test was 37.4 μg/dL (SD: 23.1; range: 5-94.3), and consistent with chronic Pb exposure. Although PbB levels declined in the study group between the two test periods, performance on the RCPM and Digit Span tests tended to become poorer over time, suggesting long-term adverse neurocognitive effects of chronic Pb exposure. Conclusion: The findings of this study on children with chronic Pb exposure showed poorer performance on measures of visual-spatial intelligence and auditory memory/attention over a period of several years, suggesting increasing adverse neurocognitive effects of chronic Pb exposure.