ABSTRACT
Recent studies have reached mixed conclusions regarding the association between exposure to air pollutants and attention-deficit hyperactivity disorder (ADHD). We performed systematic review and meta-analysis to determine whether air pollutants were risk factors for the development of ADHD in children. We systematically searched databases for all relevant studies up to 2 July 2019. Together, the studies indicated that exposure to PAHs (risk ratio (RR): 0.98, 95% confidence interval (CI): 0.82–1.17), NOx (RR: 1.04, 95% CI: 0.94–1.15), and PM (RR: 1.11, 95% CI: 0.93–1.33) did not have any material relationship with an increased risk of ADHD. Heterogeneity of study data was low (I2: 2.7%, P = 0.409) for studies examining PAHs, but was substantial for NOx and PM (I2: 68.4%, P = 0.007 and I2: 60.1%, P = 0.014, respectively). However, these results should be interpreted with caution since the number of epidemiological studies investigating this issue were limited.
Acknowledgments
All authors contributed to the study conception and design. Material preparation, data collection, and analysis were performed by Changhong Wang, Xinxin Zhang, Huiling Song, and Yan Li. The first draft of the manuscript was written by Mengjie Zhang and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.
Declaration of conflicting interest
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Supplementary material
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