Abstract
Human volunteers were exposed to artificially generated caprolactam vapors to establish irritant response and discomfort threshold. At high relative humidities, response was absent at all concentrations up to 14 ppm. At low relative humidities, distress was dose responsive in the range 10-100 ppm. There was no response below 7 ppm. Distress was not incapacitating below 100 ppm. The authors suggest a time-weighted average concentration limit of 5 ppm to prevent discomfort in unacclimated workers, and conclude that excursion limits of less than 50 ppm are not justified by the evidence. Previously reported skin effects of dust (as opposed to vapor) exposure were confirmed from medical records.