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A study of the cardiac effects of bromochlorodifluoromethane (halon 1211) exposure during exercise
J D Kaufman1, M S Morgan, M L Marks
1Department of Medicine, University of Washington, Seattle.
Insights
Exposure to bromochlorodifluoromethane (halon 1211) may cause cardiac issues like arrhythmias in firefighters. While not statistically significant, findings suggest potential cardiotoxicity from occupational fluorocarbon exposure.
Area of Science:
- Occupational Health
- Cardiology
- Environmental Toxicology
Background:
- Fluorocarbons, including bromochlorodifluoromethane (halon 1211), are associated with potential cardiac adverse effects.
- Previous research suggests a link between fluorocarbon exposure and conditions like myocardial depression and ventricular arrhythmias.
Purpose of the Study:
- To investigate the cardiotoxic effects of occupational exposure to bromochlorodifluoromethane (halon 1211) in healthy firefighters.
- To assess the impact of halon 1211 exposure on cardiac function during exercise.
Main Methods:
- A double-blind, placebo-controlled crossover study involving ten healthy firefighters aged 40-50.
- Participants were exposed to 1,000 ppm halon 1211 while exercising, with cardiac monitoring during and after exposure.
Main Results:
- Two subjects experienced complex ectopy (ventricular couplets, idioventricular rhythm) during halon exposure, versus none with placebo.
- One subject exhibited a significantly higher rate of ventricular premature beats (VPBs) with halon exposure compared to placebo.
- A blunted systolic blood pressure response during exercise was observed in 80% of subjects exposed to halon 1211.
Conclusions:
- Findings suggest that occupational exposure to bromochlorodifluoromethane may be cardiotoxic in susceptible individuals.
- The study highlights potential cardiac risks for firefighters exposed to halon 1211.
- Limited statistical power due to small sample size necessitates further research to confirm these cardiotoxic effects.
Abstract:
Bromochlorodifluoromethane (halon 1211, a fire extinguisher), like other fluorocarbons, has been linked with ventricular arrhythmias and myocardial depression. Ten healthy firefighters, aged 40-50, were exposed to 1,000 ppm halon while exercising, in a double-blind, placebo-controlled crossover experiment, and were monitored during and after exposure. Complex ectopy (ventricular couplets and idioventricular rhythm) occurred in two subjects with halon, but none with placebo. One subject had 49.5 ventricular premature beats (VPB)/hour during the period of halon exposure and subsequent 8 hours and only 8.7 VPB/hour during the same period of placebo. In addition, 8 of the 10 subjects had a smaller systolic blood pressure rise during exercise with halon than with placebo. None of the observed differences was statistically significant. These results are consistent with findings in other investigations, suggesting that occupational fluorocarbon exposures may be cardiotoxic in certain individuals, although the small sample sizes used in this and other studies have resulted in limited statistical power to demonstrate this effect.