Background: DNA methylation changes are potential pathways of environmentally induced health effects. We investigated whether exposure to ambient concentrations of NO2, PM10, PM2.5 and O3 and traffic parameters were associated with global DNA methylation in blood of healthy adults.
Methods: 48 non-smoking adults (25 males) with a median age of 39years were sampled in winter and summer. Global DNA methylation in whole blood (% 5-methyl-2'-deoxycytidine, %5mdC) was analyzed with HPLC. Exposure to air pollutants at the home address was assessed using interpolated NO2, PM10, PM2.5 and O3 concentrations for various exposure windows (60- to 1-day moving average exposures and yearly averages) and GIS-based traffic parameters. Associations between pollutants and %5mdC were tested with multiple mixed effects regression models.
Results: Average %5mdC (SD) was 4.30 (0.08) in winter and 4.29 (0.08) in summer. Men had higher %5mdC compared to women both in winter (4.32 vs. 4.26) and summer (4.31 vs. 4.27). When winter and summer data were analyzed together, various NO2, PM10 and PM2.5 moving average exposures were associated with changes in %5mdC (95% CI) ranging from -0.04 (-0.09 to 0.00) to -0.14 (-0.28 to 0.00) per IQR increase in pollutant. NO2, PM10, PM2.5 and O3 moving average exposures were associated with decreased %5mdC (95% CI) varying between -0.01 (-0.03 to 0.00) and -0.17 (-0.27 to -0.06) per IQR increase in pollutant in summer but not in winter.
Conclusion: Decreased global DNA methylation in whole blood was associated with exposure to NO2, PM10, PM2.5 and O3 at the home addresses of non- adults. Most effects were observed for the 5- to 30-day moving average exposures.
Keywords: %5mdC; 2′-deoxycytidine; 5-hydroxymethyl-cytosine; 5-methyl-2′-deoxycytidine; 5-methyl-cytosine; 5hmC; 5mC; 5mdC; Air pollution; BC; BMI; CI; DNA methylation; Epigenetics; GIS; GSH; Human biomonitoring; IQR; LINE-1; NO; NO(2); O(3); Ozone; PM; PM(10); PM(2.5); S-adenosylmethionine; SAM; SD; WBC; black carbon; body mass index; confidence interval; dC; geographical information system; glutathione; iNOS; inducible nitric oxide synthase; interquartile range; long interspersed nucleotide elements; nitric oxide; nitrogen dioxide; ozone; particulate matter with aerodynamic diameter≤10μm; particulate matter with aerodynamic diameter≤2.5μm; percentage 5mdC; standard deviation; white blood cells.