Background Adverse biological effects from airborne pollutants are a primary
environmental concern in highly industrialized areas. Recent studies linked air pollution
exposures with altered blood Deoxyribo-nucleic acid (DNA) methylation, but effects from
industrial sources and underlying biological mechanisms are still largely unexplored.
Methods The Ma Ta Phut industrial estate (MIE) in Rayong, Thailand hosts one
of the largest steel, oil refinery and petrochemical complexes in south-eastern Asia. We
measured a panel of blood DNA methylation markers previously associated with air pollution
exposures, including repeated elements [long interspersed nuclear element-1 (LINE-1) and
Alu] and genes [p53, hypermethylated-in-cancer-1
(HIC1), p16 and interleukin-6
(IL-6)], in 67 MIE workers, 65 Ma Ta Phut residents and 45 rural
controls. To evaluate the role of DNA damage and oxidation, we correlated DNA methylation
measures with bulky DNA and
deoxyguanosine (M1dG) adducts.
Results In covariate-adjusted models, MIE workers, compared with rural
residents, showed lower LINE-1 (74.8% vs 78.0%; P <
0.001), p53 (8.0% vs 15.7%; P <
0.001) and IL-6 methylation (39.2% vs 45.0%;
P = 0.027) and higher HIC1 methylation
(22.2% vs 15.3%, P < 0.001). For all four markers, Ma Ta
Phut residents exhibited methylation levels intermediate between MIE workers and rural
controls (LINE-1, 75.7%, P < 0.001; p53,
9.0%, P < 0.001; IL-6, 39.8%,
P = 0.041; HIC1, 17.8%,
P = 0.05; all P-values vs rural controls).
Bulky DNA adducts showed negative correlation with p53 methylation
(P = 0.01). M1dG showed negative correlations with
LINE-1 (P = 0.003) and IL-6 methylation
(P = 0.05).
Conclusions Our findings indicate that industrial exposures may induce
alterations of DNA methylation patterns detectable in blood leucocyte DNA. Correlation of
DNA adducts with DNA hypomethylation suggests potential mediation by DNA damage.