Nasal inflammatory and respiratory parameters in human volunteers during and after repeated exposure to chlorine

The objectives of this study were: 1) to determine if chlorine exposure at low levels induces nasal effects in humans as it does in rodents; and 2) to establish a possible occurrence of respiratory effects in human volunteers exposed to chlorine vapour at concentrations of 0, 0.1, 0.3 and 0.5 ppm. The study was conducted in a double-blind fashion in 8 male volunteers usin g a repeated measures design, with randomly selected exposure sequences. Su bjects were exposed for 6 h.day(-1) on 3 consecutive days to each of the 4 exposure conditions. In nasal lavage, interleukin-8 (IL-8), albumin, total cell number, and percentages of neutrophils, lymphocytes, monocytes, eosino phils, and epithelial cells were determined. The lung function parameters t hat mere analysed included forced vital capacity (FVC), forced expiratory v olume in first second (FEV1), FEV1/FVC ratio, and maximal mid expiratory fl ow (MMEF), Data analysis was limited to 7 subjects since one volunteer deci ded to stop participating for reasons not related to the study. Nasal lavage measurements did not support an inflammatory response or irrit ant effects on the nasal epithelium. For FVC, FEV1, and FEV1/FVC, no signif icant differences were found. MMEF was significantly different between the 0 and 0.5 ppm exposure, but this was attributed to an unexplained shift in baseline values during control(0 ppm) exposure. The present data does not support an inflammatory effect in the nose nor sh ows changes in respiratory function at repeated exposure up to 0.5 ppm. Thi s discrepancy with previous data in rodents can be attributed at least in p art to differences in respiratory tract airflow characteristics.