Influence of traffic-related air pollution exposure on respiratory health, TNfa and CYP1A1 gene and histone modifications among school children in the Klang Valley, Malaysia

Traffic-related air pollution (TRAP) is a complex mixture of many pollutants, which has adverse health impacts, especially on children who live near heavilytravelled roads. This cross-sectional comparative study was conducted at eight schools in high traffic (HT) and low traffic (LT) areas to investigate the potential risks from TRAP exposure to respiratory health among children with the incorporation of histone H3 level and deoxyribonucleic acid methylation (DNAm) status of Tumour Necrosis Factor Alpha (TNFα) and Cytochrome P450 Family 1 Subfamily A Member 1 (CYP1A1). Respondents’ background information, personal exposure to TRAP, and respiratory symptoms were obtained from validated questionnaires distributed to randomly selected 7 to 11-year-old children to be filled in by parents or guardians. Portable instruments equipped with integrated sensors for real-time monitoring were used for 6-h measurements of coarse particulate matter (PM10), fine particulate matter (PM2.5), extremely fine particulate matter (PM1), nitrogen dioxide (NO2), sulphur dioxide (SO2), ozone (O3), carbon monoxide (CO), and total volatile organic compounds (TVOC). Meanwhile, 24-h measurements of PM2.5-bound black carbon (BC) in schools and particulate matters in residences were performed using air sampling pumps that utilise the gravimetric method. Data from local air quality monitoring stations were also compared to validate the school findings and proceeded with Principal Component Analysis (PCA) to identify pollution sources. A lung function test was conducted using a spirometer to measure lung performance. Histone H3 modification was captured using an enzyme-linked immunosorbent assay (ELISA) kit, whereas DNAm was quantified using a methylation-specific polymerase chain reaction (MS-PCR) kit on bisulphite-treated DNA; both from saliva samples. The results indicate that HT area had significantly higher concentrations of PM10 (p<0.001), PM2.5 (p<0.001), PM1 (p<0.001), BC (p<0.001), NO2 (p<0.001), SO2 (p<0.001), O3 (p<0.001), CO (p<0.001) and TVOC (p<0.001) than LT area. The PCA results highlighted that the air quality in the HT area had been affected by the combustion of fuel engines. Children who attended schools in the HT area were more prone to get cough (OR=3.0), phlegm (OR=2.3), wheezing (OR=2.3), impairment in forced vital capacity (FVC%)(z= - 5.23), impairment in forced expiratory volume in 1 second (FEV1%)(z= -5.01), higher histone H3 level (z= -5.13), methylated TNFα (OR=2.0) and methylated CYP1A1 (OR=1.7). After controlling the possible confounders, findings from multiple logistic regression show that methylated TNFα and CYP1A1 were mostly influenced by exposure to NO2 (OR=3.0) and BC (OR=2.0), respectively. Meanwhile, results from multiple linear regression revealed that BC and NO2 were the most significant factors influencing the FVC% (adjusted R2=0.405, p<0.001, f2=0.68) among children. FEV1% were mostly influenced by BC, PM1 and PM2.5 (adjusted R2=0.412, p<0.001, f2=0.70), whereas NO2 was the most significant factor that influenced the histone H3 level (adjusted R2=0.337, p<0.001, f2=0.51) among children. In conclusion, epigenetic mechanisms may govern the relationships between TRAP exposures and respiratory health by acting as mediators. This study also provides the groundwork for future preventive interventions, particularly developing mitigation plans to reduce TRAP exposure in Malaysia.

Text FPSK(p) 2021 14 - IR.1.pdf Download (2MB)

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