title: Short-term metal particulate exposures decrease cardiac acceleration and deceleration capacities in welders: a repeated-measures panel study.
abstract: OBJECTIVE
  Acceleration (AC) and deceleration (DC) capacities measure heart rate variability during speeding up and slowing down of the heart, respectively. We investigated associations between AC and DC with occupational short-term metal PM2.5 exposures.
  
  
  METHODS
  A panel of 48 male welders had particulate matter less than 2.5 microns in diameter (PM2.5) exposure measurements over 4-6 h repeated over 5 sampling periods between January 2010 and June 2012. We simultaneously obtained continuous recordings of digital ECG using a Holter monitor. We analysed ECG data in the time domain to obtain hourly AC and DC. Linear mixed models were used to assess the associations between hourly PM2.5 exposure and each of hourly AC and DC, controlling for age, smoking status, active smoking, exposure to secondhand smoke, season/time of day when ECG reading was obtained and baseline AC or DC. We also ran lagged exposure response models for each successive hour up to 3 h after onset of exposure.
  
  
  RESULTS
  Mean (SD) shift PM2.5 exposure during welding was 0.47 (0.43) mg/m(3). Significant exposure-response associations were found for AC and DC with increased PM2.5 exposure. In our adjusted models without any lag between exposure and response, a 1 mg/m(3) increase of PM2.5 was associated with a decrease of 1.46 (95% CI 1.00 to 1.92) ms in AC and a decrease of 1.00 (95% CI 0.53 to 1.46) ms in DC. The effect of PM2.5 on AC and DC was maximal immediately postexposure and lasted 1 h following exposure.
  
  
  CONCLUSIONS
  There are short-term effects of metal particulates on AC and DC.
authors.affiliation: Department of Environmental Health, Harvard T. H. Chan School of Public Health, Boston, Massachusetts, USA.
authors.forename: Peter E
authors.identifier: http://orcid.org/0000-0002-3996-2448
authors.initials: PE
authors.lastname: Umukoro
authors.affiliation: Department of Environmental Health, Harvard T. H. Chan School of Public Health, Boston, Massachusetts, USA Department of Community Medicine and Health Care, University of Connecticut Health Center, Farmington, Connecticut, USA.
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Cavallari
authors.affiliation: Department of Environmental Health, Harvard T. H. Chan School of Public Health, Boston, Massachusetts, USA.
authors.forename: Shona C
authors.initials: SC
authors.lastname: Fang
authors.affiliation: Department of Environmental Health, Harvard T. H. Chan School of Public Health, Boston, Massachusetts, USA.
authors.forename: Chensheng
authors.initials: C
authors.lastname: Lu
authors.affiliation: Department of Biostatistics, Harvard T. H. Chan School of Public Health, Boston, Massachusetts, USA.
authors.forename: Xihong
authors.initials: X
authors.lastname: Lin
authors.affiliation: Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, Massachusetts, USA Cardiovascular Epidemiology Research Unit, Beth Israel Deaconess Medical Center/Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Murray A
authors.initials: MA
authors.lastname: Mittleman
authors.affiliation: Department of Environmental Health, Harvard T. H. Chan School of Public Health, Boston, Massachusetts, USA Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, Massachusetts, USA Pulmonary and Critical Care Unit, Massachusetts General Hospital/Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: David C
authors.initials: DC
authors.lastname: Christiani
mesh_terms: D000054:Acceleration; D000328:Adult; D000395:Air Pollutants, Occupational / Q000009:adverse effects* / Q000032:analysis; D015716:Electrocardiography, Ambulatory; D006321:Heart / Q000187:drug effects* / Q000503:physiopathology; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D016014:Linear Models; D008137:Longitudinal Studies; D008297:Male; D008670:Metals / Q000009:adverse effects*; D008875:Middle Aged; D016273:Occupational Exposure / Q000009:adverse effects* / Q000032:analysis; D052638:Particulate Matter / Q000009:adverse effects* / Q000032:analysis; D014896:Welding; D014937:Work
chemical_list: D000395:Air Pollutants, Occupational; D008670:Metals; D052638:Particulate Matter
keywords: Deceleration; Electrocardiography; Heart Rate; Occupational Exposure