Global DNA methylation in earthworms: A candidate biomarker of epigenetic risks related to the presence of metals/metalloids in terrestrial environments

► Several metals and metalloids contribute to epigenetic gene regulation. ► As, Hg, Se, Sb inversely correlated with global DNA methylation in earthworms. ► Biomethylation of the above elements in worms suggested. ► Elements biomethylation apparently competes with DNA methylation. ► DNA methylation a biomarker of epigenetic risks related to soil metals/metalloids.