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 expiratory flow and respiratory symptoms were measured before and after each weekly 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, the short-term exposure effect was diminished during the first 4 wk, suggesting at least partial acclimatization. Symptom reporting was also associated with exposure during the previous 2.5 hr, and similar evidence of acclimatization was observed. These results suggest that there are two different time scales of response to formaldehyde, and they emphasize the need for longitudinal studies, characterized by quantitative exposure characterization, and frequent measurements of outcome.

Reversible pulmonary responses to formaldehyde. A study of clinical anatomy students.

Epidemiologic studies of irritants are difficult to perform using standard epidemiologic methods for several reasons, including the reversible nature of the health outcomes, the selection of sensitive individuals from the study population, and the wide heterogeneity in normal responses to irritants. This study examined the feasibility of using repeated measurements of peak expiratory flow (PEF) and reported symptoms to study respiratory irritants and their effects in students exposed to formaldehyde during a clinical anatomy laboratory course. We studied 24 physical therapy students dissecting cadavers for 3 h per week over a 10-wk period. Formaldehyde exposures in the breathing zone ranged from 0.49 to 0.93 ppm (geometric mean +/- geometric SD, 0.73 +/- 1.22). Irritant symptoms increased strongly over the course of the average laboratory period, but this effect was stronger at the beginning than at the end of the semester. PEF measured before each laboratory session declined over the semester by an average of about 10 L/min (2% of baseline), a trend that was statistically significant in random-effects regression models. After 14 wk away from the laboratory, the group's mean baseline PEF had returned to its preexposure level. Mean PEF also declined over each laboratory period, although this effect was attenuated over the course of the semester. Other important predictors of cross-laboratory PEF decrements were asthma and reporting throat irritation during the laboratory. It appears that mild irritant effects can be detected in naive subjects using a repeated monitoring design and relatively simple instrumentation.