Prenatal/Early-Life Exposure to Polycyclic Aromatic Hydrocarbons (PAHs) and Adverse Neurodevelopment Outcomes in Children: A Systematic Review and Meta-Analysis

Background: Research indicates prenatal/early-life exposure to PAHs may be associated with adverse neurodevelopment outcomes, but there are conflicting research results. A weight of evidence approach is needed. Objective: Summarize eligible evidence of prenatal/early-life PAH exposure on neurodevelopment outcomes in children. Methods: Using a priori search strategy, we conducted a systematic review (SR) to identify eligible peer-reviewed studies in English, in PubMed, Wed of Science, and Google Scholar. Eligible studies modeled or measured PAH exposure during pregnancy or at least six months prior to neurodevelopment assessment, with no limits on study time-period or geography. Two reviewers, working independently, followed PRISMA protocol. Risk of bias assessment followed Navigation Guide protocol. Of 613 studies identified, 26 were included in final meta-analysis. Outcomes were grouped into either dichotomous (summary effect measure: odds ratio) or continuous outcomes (Cohen’s d). We report the summary effect size of each outcome, 95%CI, and I2. Results: We found a statistically significant positive association in dichotomous outcomes between prenatal/early-life PAH exposure and anxiety/depression (OR: 1.36; 95%CI:1.10,1.68; p=0.005; npooled=4,989; I2=73.6%), and in neurodevelopment delay (1.07; 95%CI: 1.01, 1.14; p =0.028; npooled = 1,113; I2 = 30.2%). We found a marginal positive association with attention problems (OR: 1.81; 95%CI:0.96,3.43; p=0.068; npooled=2,997; I2=86.4%). In continuous outcomes, we found a statistically significant negative association in motor skills (Cohen’s d: -0.371; 95%CI:-0.52,-0.22; p<0.001; npooled=1,372; I2=96.7%), and in adaptive behavior (-0.142, 95%CI:-0.25,-0.00; p=0.042; npooled = 1,128; I2=84.3%). We did not find an association in intelligence, language skills, social behavior, ADHD, or other behavior problems. Conclusion: There is limited human evidence that prenatal/early-life PAH exposure adversely affects neurodevelopment. Between-study variance was low to high. However, limited human evidence of adverse neurodevelopment effects associated with prenatal/early-life exposure to common environmental pollutants is cause for concern.