title: Heart rate variability and DNA methylation levels are altered after short-term metal fume exposure among occupational welders: a repeated-measures panel study.
abstract: BACKGROUND
  In occupational settings, boilermakers are exposed to high levels of metallic fine particulate matter (PM2.5) generated during the welding process. The effect of welding PM2.5 on heart rate variability (HRV) has been described, but the relationship between PM2.5, DNA methylation, and HRV is not known.
  
  
  METHODS
  In this repeated-measures panel study, we recorded resting HRV and measured DNA methylation levels in transposable elements Alu and long interspersed nuclear element-1 (LINE-1) in peripheral blood leukocytes under ambient conditions (pre-shift) and right after a welding task (post-shift) among 66 welders. We also monitored personal PM2.5 level in the ambient environment and during the welding procedure.
  
  
  RESULTS
  The concentration of welding PM2.5 was significantly higher than background levels in the union hall (0.43 mg/m3 vs. 0.11 mg/m3, p < 0.0001). The natural log of transformed power in the high frequency range (ln HF) had a significantly negative association with PM2.5 exposure (β = -0.76, p = 0.035). pNN10 and pNN20 also had a negative association with PM2.5 exposure (β = -0.16%, p = 0.006 and β = -0.13%, p = 0.030, respectively). PM2.5 was positively associated with LINE-1 methylation [β = 0.79%, 5-methylcytosince (%mC), p = 0.013]; adjusted for covariates. LINE-1 methylation did not show an independent association with HRV.
  
  
  CONCLUSIONS
  Acute decline of HRV was observed following exposure to welding PM2.5 and evidence for an epigenetic response of transposable elements to short-term exposure to high-level metal-rich particulates was reported.
authors.forename: Tianteng
authors.initials: T
authors.lastname: Fan
authors.forename: Shona C
authors.initials: SC
authors.lastname: Fang
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Cavallari
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Barnett
authors.forename: Zhaoxi
authors.initials: Z
authors.lastname: Wang
authors.forename: Li
authors.initials: L
authors.lastname: Su
authors.forename: Hyang-Min
authors.initials: HM
authors.lastname: Byun
authors.forename: Xihong
authors.initials: X
authors.lastname: Lin
authors.forename: Andrea A
authors.initials: AA
authors.lastname: Baccarelli
authors.affiliation: Department of Environmental Health, Harvard School of Public Health, Boston, MA 02115, USA. dchris@hsph.harvard.edu.
authors.forename: David C
authors.initials: DC
authors.lastname: Christiani
mesh_terms: D000328:Adult; D015331:Cohort Studies; D019175:DNA Methylation / Q000235:genetics*; D004251:DNA Transposable Elements / Q000235:genetics; D006339:Heart Rate; D006801:Humans; D007962:Leukocytes / Q000378:metabolism*; D020084:Long Interspersed Nucleotide Elements / Q000235:genetics; D008137:Longitudinal Studies; D008297:Male; D008670:Metals; D008875:Middle Aged; D016273:Occupational Exposure / Q000009:adverse effects* / Q000032:analysis; D052638:Particulate Matter / Q000009:adverse effects* / Q000032:analysis; D014896:Welding
chemical_list: D004251:DNA Transposable Elements; D008670:Metals; D052638:Particulate Matter