Cardiac arrhythmias during occupational exposure to fluorinated hydrocarbons

The effects of occupational exposure to chlorodifluoromethane (FC 22) and dichlorodifluoromethane (FC 12) on cardiac rhythm were examined. The subjects were six men who repaired refrigerators (age 31-56, mean 46 years) and a control group of six plumbers (age 29-54, mean 45 years). Ambulatory electrocardiograms (ECG) were recorded for 24 hours on the day of exposure and on a control day. The ECG tapes were automatically analysed with a Reynolds pathfinder 3 apparatus and all aberrant complexes recorded by the machine were checked. One person read all the tapes without knowing whether or not they were recorded during exposure. The number of ventricular ectopic beats were compared between the day of exposure and the control day and with the tape of the control. In addition, the number of ventricular ectopic beats during exposure was compared with the number occurring during the rest of the day. The concentrations of fluorocarbons were measured in four instances. High peak concentrations of fluorocarbons (1300-10,000 cm3/m3) were measured during refrigerator repair work. No clear connection between fluorocarbons and cardiac arrhythmia was found, although one subject had several ventricular ectopic beats which may have been connected with exposure.