Relationship between Air and Soil Pollution and Cognitive Skills Related to the Brain of Children in the Age Range of 4 to 12 Years: A Systematic Review

Abstract

Background and purpose: Environmental pollution, is one of the main causes of increasing cognitive-neurological disorders. All pollutants, whether biodegradable or non-biodegradable, contribute to various neurological issues, including cognitive disorders, and affect human life, particularly in the early stages of development. Given the growing concern about the impact that air pollutants may have on children's learning and neural development, the current research aims to determine the relationship between exposure to pollution and neural development skills in children, in the early stages of education and schooling. Materials and methods: The present systematic review was conducted following international standards and according to the PRISMA checklist. English-language articles were searched from PubMed, Scopus, and Web of Science, Science Direct, and Google Scholar databases until September 2023. Eligible articles were screened by reading titles and abstracts by the researcher. Then, the full text of relevant articles was evaluated, and discrepancies were resolved before making the final decision. The studies reviewed in this research included air and soil pollution, one of the cognitive and learning disorders such as attention, memory, intelligence, thinking, neural development, etc., preschool, and elementary school. In the present study, articles were fully reviewed, and research that did not fall within the age range of preschool and elementary school was excluded from the review; such as articles related to air pollution during the fetal period or children over the age of 12 years. Articles that simultaneously included children within and outside the age range of the study were only reviewed for the relevant age groups, and review articles were also used to find studies related to the research topic. Results: The search strategy resulted in the identification of 528 studies related to the article’s topic. Based on the screening of inclusion and exclusion criteria, eventually 37 articles were selected that matched the objectives of this research. The results indicated a wide heterogeneity in neuropsychological assessment tools, geographical regions, and sample sizes recorded. Also, many findings reported significant detrimental effects of air pollutants on cognitive functions and sensory-motor abilities (reported a significant difference in terms of brain white matter volume and motor abilities among children exposed to pollution, indicating that living in a polluted area is a risk factor for disruption in sensory-motor functions), increased risk of ADHD, reduced intelligence and cognitive performance, reduced memory, reduced attention; and reduced learning power and perception, most of which examined the effects of several pollutants on cognitive changes in children in preschool and elementary stages. In two of the articles reviewed in this research, the relationship was analyzed based on gender. In these studies, boys were at greater risk in terms of active memory. Also, in the quality assessment of articles, most articles scored 15 or higher, indicating the desirable status of most of the selected articles. Conclusion: The exposure to pollution with problems in cognitive skills; it is particularly associated with intellectual functions, attention, learning, comprehension, and memory skills. However, the association of pollution with specific neurodevelopmental skills in preschool and elementary school children is less clear and requires more research.

Keywords

• air pollution
• soil pollution
• cognitive skills
• learning
• children