Abstract
A fundamental assumption of monitoring breath for a toxicant is that the concentration of the toxicant in breath is proportional to the concentration in blood. The present study was designed, in part, to assess the conditions under which measurement of methanol in breath would be useful for estimating the blood concentration of methanol following inhalation or dermal exposures to methanol. Paid volunteer subjects underwent controlled inhalation exposure to methanol vapor at various concentrations for 8 hours, or dermal exposures (without inhalation exposure) to methanol for varying periods of time. Blood and end-expiratory air were analyzed for methanol from samples obtained prior to exposures, and at various times during and after exposures. The results demonstrate that blood and breath concentrations of methanol are disproportional for varying periods of time during and following cessation of methanol exposure, depending on the route of exposure (dermal versus inhalation). In settings where there might be opportunities for combined inhalation and dermal exposure to methanol, it would be necessary to wait at least 2 hours to collect breath specimens following cessation of methanol exposure. This prolonged waiting period might serve to decrease the attractiveness of measurement of methanol in breath as a strategy for monitoring occupational methanol exposure.
