Online Program

Short-term Metal Particulate Exposures Decrease Cardiac Acceleration and Deceleration Capacities in Welders: A repeated-measures panel study

Monday, November 2, 2015

Peter Umukoro, MD, MPH, ScD, Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA
Xihong Lin, PhD, Department of Biostatistics, Harvard School of Public Health, Harvard University, Boston, MA
David Christiani, MD, MPH, MS, Department of Environmental Health and Department of Epidemiology, Harvard T.H.Chan School of Public Health, Harvard University, Boston, MA
Background and Objective: Studies have shown negative association between short-term PM2.5 and Heart Rate Variability.  Acceleration and Deceleration Capacities – different metrics of cardiac autonomic function – measure the variability of the heart rate during speeding up and slowing down of the heart respectively. We investigated the associations between AC and DC with occupational short-term metal PM2.5exposures.

Methods: A panel of 48 male welders had simultaneous measurements of PM2.5 exposure and digital electrocardiograms (ECG). We analyzed PM and ECG data to obtain the hourly PM2.5, 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, baseline AC or DC and other covariates. We also ran lagged exposure response models for each successive hour up to 3 hours after onset of PM2.5exposure.

Results: Mean (SD) shift PM2.5 exposure during welding was 0.47 (0.43) mg/m3. Negative 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 1mg/m3 increase of PM2.5 was associated with a decrease of 1.46 (95% CI:  1.00, 1.92) msec in AC and a decrease of 1.00 (95% CI: 0.53, 1.46) msec in DC. The effect of PM2.5on AC and DC was maximal immediately post exposure and lasted 1 hour following exposure.

Conclusion: There are short-term effects of metal particulates on AC and DC.

Learning Areas:

Environmental health sciences
Occupational health and safety

Learning Objectives:
Explain the short-term effects of metallic PM2.5 exposure at work on the acceleration and deceleration capacities of the heart.

Keyword(s): Occupational Health and Safety, Environmental Health

Presenting author's disclosure statement:

Qualified on the content I am responsible for because: I have spent the last three years working on this project as a doctoral student under the supervision of David Christiani who is the Principal Investigator on this ongoing work for the last 15 years. I am a physician, undergoing training as an environmental and occupational epidemiologist with interests in occupational health and cardiovascular research. I analyzed the data for this work.
Any relevant financial relationships? No

I agree to comply with the American Public Health Association Conflict of Interest and Commercial Support Guidelines, and to disclose to the participants any off-label or experimental uses of a commercial product or service discussed in my presentation.