EVALUATION OF DERMAL AND RESPIRATORY CHLOROFORM EXPOSURE IN HUMANS

Chloroform is a known contaminant of chlorinated drinking water and of swimming pool water disinfected with chlorine or one of its derivativ es. Few data exist regarding the importance of dermal and inhalation e xposure routes to the chloroform body burden resulting from domestic a nd recreational use of chlorinated water. In our experimental study in volving 11 male swimmers, we quantified the body burden resulting from exposure to various concentrations of chloroform in water and air of an indoor swimming pool, during a daily 55-min exercise period. From t he first to the sixth exercise period, CHCl3 mean concentration in wat er was increased from 159 mu g/l to 553 mu g/l. Corresponding mean air CHCl3 level ranged from 597 ppb to 1630 ppb. To dissociate the dermal exposure route from that of inhalation, swimmers used scuba tanks dur ing an additional exercise period. Chloroform concentrations were meas ured in alveolar air before and after each exercise period, as well as after 35 min of physical activity. Chloroform levels in water and air were measured every 10 min. We examined the relationship between alve olar air concentration (a measure of body burden) at 35 and 55 min and environmental chloroform concentrations by using multiple regression models. The natural logarithm of alveolar air concentration was strong ly correlated with aqueous chloroform concentration both at 35 (p<0.00 1, r(2) = 0.75) and 55 min (p<0.001, r(2) = 0.86). The relationship wi th air concentrations was also statistically significant (35 min: p<0. 001, r(2) = 0.58, 55 min: p<0.001, r(2) = 0.63). Two other variables, intensity of exercise and physiological characteristics of the subject , were also significantly associated with variation of body burden. Ap proximately 24% of body burden resulted from dermal absorption. Swimmi ng in indoor pools may be an important source of exposure to chlorofor m.