Inverse Association of Intellectual Function with Very Low Blood Lead but Not with Manganese Exposure in Italian Adolescents

Overview

Journal Environ Res

Publisher Elsevier

Specialty Environmental Health

Date 2012 Aug 29

PMID 22925625

Citations 63

Authors

Roberto G Lucchini

Silvia Zoni

Stefano Guazzetti

Elza Bontempi

Serena Micheletti

Karin Broberg

Giovanni Parrinello

Donald R Smith

Affiliations

Soon will be listed here.

Abstract

Background: Pediatric lead (Pb) exposure impacts cognitive function and behavior and co-exposure to manganese (Mn) may enhance neurotoxicity.

Objectives: To assess cognitive and behavioral function in adolescents with environmental exposure to Pb and Mn.

Methods: In this cross sectional study, cognitive function and behavior were examined in healthy adolescents with environmental exposure to metals. The Wechsler Intelligence Scale for Children (WISC) and the Conners-Wells' Adolescent Self-Report Scale Long Form (CASS:L) were used to assess cognitive and behavioral function, respectively. ALAD polymorphisms rs1800435 and rs1139488 were measured as potential modifiers.

Results: We examined 299 adolescents (49.2% females) aged 11-14 years. Blood lead (BPb) averaged 1.71 μg/dL (median 1.5, range 0.44-10.2), mean Blood Manganese (BMn) was 11.1 μg/dL (median 10.9, range 4.00-24.1). Average total IQ was 106.3 (verbal IQ=102, performance IQ=109.3). According to a multiple regression model considering the effect of other covariates, a reduction of about 2.4 IQ points resulted from a two-fold increase of BPb. The Benchmark Level of BPb associated with a loss of 1 IQ-point (BML01) was 0.19 μg/dL, with a lower 95% confidence limit (BMLL01) of 0.11 μg/dL. A very weak correlation resulted between BPb and the ADHD-like behavior (Kendall's tau rank correlation=0.074, p=0.07). No influence of ALAD genotype was observed on any outcome. Manganese was not associated with cognitive and behavioral outcomes, nor was there any interaction with lead.

Conclusions: These findings demonstrate that very low level of lead exposure has a significant negative impact on cognitive function in adolescent children. Being an essential micro-nutrient, manganese may not cause cognitive effects at these low exposure levels.

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