Short-term effects of formaldehyde on peak expiratory flow and irritant symptoms

The authors studied the respiratory effects of formaldehyde exposure among students who dissected cadavers in a gross anatomy laboratory. Peak expirat ory flow and respiratory symptoms were measured before and after each weekl y laboratory session. Each of 38 students was exposed to formaldehyde for 2 .5 hr/wk for 14 wk. Individual, daily formaldehyde measurements averaged 1. 1 ppm (standard deviation = 0.56 ppm). Multivariate models demonstrated two different time scales of effect of formaldehyde on peak expiratory flow: ( 1) exposure during the previous 2.5 hr reduced peak expiratory flow by -1.0 % per ppm, and (2) average exposure during all preceding weeks reduced peak expiratory flow by an additional -0.5% per ppm of formaldehyde. However, t he short-term exposure effect was diminished during the first 4 wk, suggest ing at least partial acclimatization. Symptom reporting was also associated with exposure during the previous 2.5 hr, and similar evidence of acclimat ization was observed. These results suggest that there are two different ti me scales of response to formaldehyde, and they emphasize the need for long itudinal studies, characterized by quantitative exposure characterization, and frequent measurements of outcome.