Ambient air pollution and human epigenetic modifications

Abstract This chapter summarized the existing epidemiological evidence about the association between exposure to ambient air pollution and human epigenetic modifications, including DNA methylation (global DNA methylation, gene-specific DNA methylation, DNA methylation-based biomarkers, mitochondrial DNA methylation), non-coding RNAs, and histone modifications. We found that most of existing studies on this topic focused on DNA methylation. They showed generally consistent finding about the inverse association between ambient air pollution and global DNA methylation. A total of 150 micro RNAs and the methylation status of over 4240 genes have been found to be associated with ambient air pollution, but few of them have been replicated by different studies. Evidence about mitochondrial DNA methylation, DNA methylation-based biomarkers, long non-coding RNAs, and histone modifications remain scarce or inconsistent. We highlighted the value of twin and family study in this rapidly growing field, in terms of adjusting for familial confounding effects and making causal inference.