Ambient air pollution exposure and telomere length: a systematic review and meta-analysis

This study aimed to provide evidence of the associations between pre- and post-birth and adulthood air pollution exposure with telomere length.The databases of PubMed, Embase, and Web of Science were searched up to June 1st, 2022 in order to include relevant observational studies and perform a systematic review and meta-analysis.The random-effects meta-analysis was grouped by air pollutant and exposure window (pre- and post-birth and adulthood) to evaluate the summary effect estimate. Cochran's Q and I2 statistics were used to evaluate the heterogeneity among the included studies. The quality of individual studies was evaluated using the national toxicology program/office of health assessment and translation risk of bias rating tool.We identified 18 studies, covering 8506 children and 2263 adults from multiple countries. We found moderate evidence that particulate matter less than 2.5 μm (PM2.5) exposure during the entire pregnancy (-0.043, 95% CI: -0.067, -0.018), nitrogen dioxide (NO2) exposure during the first trimester (-0.016, 95% confidence interval [CI]: -0.027, -0.005), long-term adulthood PM2.5 exposure were associated with shortening telomere length. Mild to high between-study heterogeneity was observed for the most tested air pollutant-telomere length combinations in different exposure windows.This systematic review and meta-analysis provides the evidence which strongly supports that prenatal PM2.5 and NO2 exposures were related to reduced telomere length, while prenatal sulfur dioxide (SO2) and carbon monoxide (CO) exposures, childhood PM2.5, particulate matter less than 10 μm (PM10), NO2 exposures and short-term adulthood PM2.5 and PM10 exposures were not associated with telomere length. Further high-quality studies are needed to elaborate our suggestive associations.