Epigenetic markers of exposure to polycyclic aromatic hydrocarbons in Mexican brickmakers: A pilot study

A pilot cross-sectional study was carried out in a group of 39 male brick manufacturers in San Luis Potosi, Mexico to identify epigenetic biomarkers of exposure to polycyclic aromatic hydrocarbons (PAHs). A questionnaire was used to compile the smoking and drinking habits, clinical history, working time, and socioeconomic characteristics of the participants. 1-Hydroxypyrene (1-OHP) levels were measured from urine samples using high-performance liquid chromatography, and genomic DNA was isolated from blood samples for methylation analysis using pyrosequencing. The mean 1-OHP level was 0.18 μg g−1 creatinine (range 0.023–1.11), which was below the expected occupational exposure level. After adjusting for potential confounders, the 1-OHP urine concentration was negatively associated with DNA methylation of the interleukin 12 (β = −1.57; 95% CI: −2.9 to −0.23; p = 0.02) and p53 gene promoters (β = −2.7; 95% CI: −5.46–0.06; p = 0.055). Suggestive negative associations were also found for the TNF-α gene (β = −3.9; 95% CI:−8.28–0.48; p = 0.08) and Alu sequences (β = −0.55; 95% CI:−1.25–0.16; p = 0.12). Although the individual exposures to PAHs as estimated by urinary 1-OHP concentrations were low, changes in specific and global DNA methylation were observed.

► Epigenetic biomarkers can be used to assess early effects induced by PAH exposure.
► Epigenetics might change gene expression in PAH-exposed brickmakers.
► We found an association between p53 and IL-12 gene hypomethylation and PAH exposure.