Inhalation route : Inhalation absorption of vinyl chloride is rapid in humans.Results from young adult male volunteers exposed to vinyl chloride monomer concentrations of 7.5-60 mg/m3 (2.9-23.5 ppm) by gas mask for 6 hours showed that retention (mean 42%) was independent of the VC concentration inhaled and reached the highest level of 46% in the first 15 min of exposure. Since retention did not change with increasing vinyl chloride concentrations, it appears that saturation of the major pathway of overall metabolism did not occur in this exposure regimen (Krajewski et al., 1980).