Exposures of Health-Care Workers to Ribavirin Aerosol: A Pharmacokinetic Study

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Abstract
We assessed health risks to nurses and therapists exposed occupationally to ribavirin aerosol, a known rodent teratogen, by measuring uptake as a function of exposure concentration. During a 4-d period, healthy, nonsmoking, young adult volunteers (N = 14) were exposed 4 h/d to respirable ribavirin aerosol at concentrations that exceeded occupational levels. Intermittent exercise occurred during exposure, and all activities occurred in a simulated hospital room. Ribavirin was assayed in plasma, red cells, and urine; lung function and symptoms were also measured. In 7 volunteers who were exposed to 30 mg/m3 (i.e., received ≈ 10% of therapeutic dose), postexposure ribavirin concentrations in plasma and urine were similar on all 4 d, averaging 0.89 μmol/l and 131 μmol/l, respectively. These concentrations decreased after exposure, with half-times of 37–39 h. Red-cell concentrations averaged 31 μmol/l on d 4, accounting for < 5% of inhaled ribavirin mass, and they remained stable for 4 d afterward. In 7 volunteers exposed to 3 mg/m3 (i.e., ≈ % of therapeutic dose), plasma averaged 0.075 μmol/l and red cells averaged 3 μmol/l on d 4 (i.e., near detection limits). Small variations occurred in lung function, reported symptoms, and hematologic values for exposures to both 3 and 30 Mu;g/m3; therefore, these effects were most likely not caused by ribavirin. Typical occupational exposures to ribavirin, without recommended protective measures, should result in undetectable or barely detectable body burdens, i.e., approximately 0.1%–1% of levels reported to be toxic to laboratory animals.