Abstract
Interest has developed in the use of urinary formic acid as a biologic exposure index of occupational methanol exposure. Four human subjects were exposed to approximately 200 ppm of methanol in a test chamber for 6 hours. Ambient air in the chamber was monitored for methanol, while urine was monitored for formic acid. Urine specimens were collected immediately before, immediately after, and 16 hours following cessation of exposure to methanol. Mean urinary formic acid was increased from baseline at the end of the exposure session (though not significantly), but had returned to baseline in samples collected 16 hours following cessation of exposure. These results suggest that measurement of urinary formic acid in specimens collected 16 hours following cessation of exposure to methanol may not be an appropriate approach to biologically assess methanol exposure.