Exposition générale au plomb et au mercure: problèmes psychologiques et comportementaux chez les enfants

Aperçu: G.M.

Les dommages potentiels causés par l'exposition aux métaux non essentiels, en particulier le mercure (Hg) et le plomb (Pb), ont été au centre de la recherche depuis des années. L'intérêt initial portait sur des expositions relativement élevées; Cependant, des données récentes suggèrent que même des expositions de fond pourraient avoir des conséquences néfastes pour le développement de l'enfant. L'identification de l'ampleur de ces conséquences est maintenant une priorité.

L'équipe a évalué les taux de Pb et de Hg sanguins dans un échantillon biracial d'enfants de 9 à 11 ans (N = 203). Les évaluations du développement neuropsychologique et psychologique comprenaient l'hostilité, les comportements perturbateurs, la régulation de l'émotion et les comportements du spectre du spectre de l'autisme.

Les réponses parasympathiques (vagales) au stress aigu étaient indexées par la variabilité du rythme cardiaque (VRC) au repos et pendant le stress.

Avec l'augmentation des niveaux de Pb, les enfants présentent des niveaux plus élevés de comportement de défiance hostile et de comportements défiants d'opposition, étaient plus insatisfaits et incertains quant à leurs émotions et avaient des difficultés avec la communication.  

Ces associations significatives ont été trouvées dans une gamme de niveaux de Pb sanguins de 0,19 à 3,25 μg / dL, bien en dessous de la «valeur de référence» pour les enfants de> 5 μg / dL. La réactivité vagale interagissait avec le Hg de sorte que l'augmentation de la Hg était associée à des comportements croissants du spectre de l'autisme pour les enfants subissant un tonus vagal soutenu pendant le stress aigu. 

Environ Res. 2017 Jul 14;158:576-582. doi: 10.1016/j.envres.2017.06.033.

Background lead and mercury exposures: Psychological and behavioral problems in children

Gump BB¹, Dykas MJ², MacKenzie JA³, Dumas AK⁴, Hruska B⁴, Ewart CK⁵, Parsons PJ⁶, Palmer CD⁶, Bendinskas K⁷.

Author information

1

Department of Public Health, Food Studies, and Nutrition, Syracuse University, United States. Electronic address: bbgump@syr.edu

2

Department of Psychology, State University of New York College at Oswego, United States.

3

Department of Biological Sciences, State University of New York College at Oswego, United States.

4

Department of Public Health, Food Studies, and Nutrition, Syracuse University, United States.

5

Department of Psychology, Syracuse University, United States.

6

Laboratory of Inorganic and Nuclear Chemistry, Wadsworth Center, New York State Department of Health, United States; Department of Environmental Health Sciences, School of Public Health, The University at Albany, United States.

7

Department of Chemistry, State University of New York College at Oswego, United States.

Abstract

BACKGROUND:

The potential harm from exposure to nonessential metals, particularly mercury (Hg) and lead (Pb), has been the focus of research for years. Initial interest focused on relatively high exposures; however, recent evidence suggests that even background exposures might have adverse consequences for child development. Identifying the extent of these consequences is now a priority.

METHODS:

We assessed blood Pb and Hg levels in a biracial sample of 9-11 year-old children (N = 203). Neurodevelopment and psychological functioning assessments included hostility, disruptive behaviors, emotion regulation, and autism spectrum disorder behaviors. Parasympathetic (vagal) responses to acute stress were indexed by heart rate variability (HRV) at rest and during stress.

RESULTS:

With increasing Pb levels, children exhibit higher levels of hostile distrust and oppositional defiant behaviors, were more dissatisfied and uncertain about their emotions, and had difficulties with communication. These significant associations were found within a range of blood Pb levels from 0.19 to 3.25μg/dL, well below the "reference value" for children of >5μg/dL. Vagal reactivity interacted with Hg such that increasing Hg was associated with increasing autism spectrum behaviors for those children with sustained vagal tone during acute stress.

CONCLUSIONS:

This study is the first to demonstrate an association between very low-level Pb exposure and fundamental psychological mechanisms that might explain prior associations with more complex outcomes such as delinquency. Analyses of vagal reactivity yielded entirely novel associations suggesting that Hg may increase autism spectrum behaviors in children with sustained vagal tone during acute stress. The novelty of these later findings requires additional research for confirmation and the cross-sectional nature of the data caution against assumptions of causality without further research.

Copyright © 2017 Elsevier Inc. All rights reserved.

PMID:28715786

DOI:10.1016/j.envres.2017.06.033