Regression analyses adjusted for age, smoking status, and occupation showed distinct associations of methylation markers with UCd (Fig. 1). In the total population, MGMT methylation decreased by 16.6% with an IQR increase in UCd levels (p < 0.001). Among men, MGMT methylation decreased by 24.7% and LINE-1 methylation increased by 1% with an IQR increase in UCd (p = 0.003; p = 0.04). Among women, DNMT3B methylation decreased by 8.5% and MT2A methylation decreased by 7.4% with an IQR increase in UCd (p = 0.04; p = 0.03). Methylation markers were not correlated with each other.