title: Time course of heart rate variability decline following particulate matter exposures in an occupational cohort.
abstract: Although research suggests that particles influence cardiac autonomic response as evidenced by decreases in heart rate variability (HRV), the time course of the response remains unclear. Using a crossover panel study, we monitored 36 male boilermaker welders, occupationally exposed to metal-rich particulate matter (PM) to investigate the temporal trend of hourly HRV subsequent to PM exposure. Ambulatory electrocardiograms were collected over work (exposure) and non-work (control) periods and the mean of the standard deviations of all normal-to-normal intervals for all 5-min segments (SDNN(i)) was calculated hourly for up to 14-hrs post-work. The exposure-response relationship was examined with linear mixed effects regression models to account for participants monitored over multiple occasions. Models were adjusted for non-work HRV to control for diurnal fluctuations and individual predictors of HRV. The mean (SD) work PM(2. 5) concentration was 1.12 (0.76) mg/m(3). Hourly SDNN(i) was consistently lower post-work as compared to the same time period on a non-work day. HRV was inversely associated with work PM(2. 5) exposures in each of the 14-hrs post-work. The hourly associations suggested an early and later phase response, with the largest regression coefficients observed 2-3 hrs (beta = -6.86 (95% CI: -11.91, -1.81) msec/1 mg/m(3) at 3-hrs), and then 9-13 hrs (beta = -8.60 (95% CI: -17.45, 0.24) msec/1 mg/m(3) at 11-hrs), after adjusting for non-work HRV, smoking status, and age. This investigation demonstrates declines in HRV for up to 14 hours following PM exposure and a multiphase cardiovascular autonomic response with immediate (2 hrs) and delayed (9-13 hrs) responses.
authors.affiliation: Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA. jcavalla@hsph.harvard.edu
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Cavallari
authors.forename: Shona C
authors.initials: SC
authors.lastname: Fang
authors.forename: Ellen A
authors.initials: EA
authors.lastname: Eisen
authors.forename: Joel
authors.initials: J
authors.lastname: Schwartz
authors.forename: Russ
authors.initials: R
authors.lastname: Hauser
authors.forename: Robert F
authors.initials: RF
authors.lastname: Herrick
authors.forename: David C
authors.initials: DC
authors.lastname: Christiani
mesh_terms: D000328:Adult; D000395:Air Pollutants, Occupational / Q000009:adverse effects*; D002940:Circadian Rhythm; D015716:Electrocardiography, Ambulatory; D004784:Environmental Monitoring; D006339:Heart Rate / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D019570:Inhalation Exposure; D008297:Male; D008669:Metallurgy; D008875:Middle Aged; D016273:Occupational Exposure / Q000009:adverse effects*; D052638:Particulate Matter / Q000009:adverse effects*; D013997:Time Factors
chemical_list: D000395:Air Pollutants, Occupational; D052638:Particulate Matter