Table 3.
Level of respiratory markers before and after swimming: linear regression coefficients of the change after swimming for the exposure parameters.
| Parameter | Percent predicted | FEV1/FVC | FeNO (ppb) | 8-Isoprostane (pg/mL) | SP-D (μg/L) | CC16 (μg/L) | |
|---|---|---|---|---|---|---|---|
| FEV1 | FVC | ||||||
| n | 48 | 48 | 48 | 47 | 45 | 48 | 48 |
| Median (IQR) | |||||||
| Before | 97.3 (90.1 to 103.6) | 98.1 (90.0 to 105.4) | 0.83 (0.8 to 0.9) | 13 (10.5 to 18.5) | 1.6 (1.0 to 2.0) | 54.4 (39.3 to 68.0) | 6.01 (3.9 to 7.7) |
| After | 96.3 (90.4 to 105.1) | 95.9 (90.7 to 104.2) | 0.83 (0.8 to 0.9) | 12.5 (10 to 17.5) | 1.3 (0.6 to 2.5) | 55.1 (45.4 to 85.0) | 6.21 (4.6 to 8.4) |
| Change | −0.6 (−2.5 to 2.4) | −2.0 (−5.1 to 3.9) | 0.0 (−0.02 to 0.04) | 0.0 (−2 to 2) | −0.03 (−0.8 to 1.1) | 1.0 (−3.7 to 6.6) | 0.47 (−0.3 to 1.1) |
| p-Value (change ≠ 0)a | 0.83 | 0.46 | 0.24 | 1.00 | 0.91 | 0.44 | 0.03 |
| Change in respiratory markers for an increase from 25th to 75th percentile in exposure parameters (95% confidence interval)b | |||||||
| Free chlorine to water (mg/L) | 0.54 (−0.90 to 1.99) | −2.44 (−5.77 to 0.88) | 0.02 (0.00−0.04)* | −1.22 (−2.51 to 0.06) | 0.61 (−0.17 to 1.39) | 0.58 (−6.26 to 7.42) | 1.02 (0.30−1.74)** |
| NHCl2 to water (μg/L) | −0.50 (−1.59 to 0.57) | 0.12 (−2.42 to 2.67) | −0.01 (−0.02 to 0.01) | 0.92 (−0.03 to 1.91) | −0.10 (−0.71 to 0.51) | 2.93 (−2.10 to 7.97) | −0.84 (−1.38 to −0.33)** |
| CHCl3 to exhaled breath (μg/m3) | 0.48 (−0.78 to 1.74) | 0.73 (−2.25 to 3.72) | 0.00 (−0.02 to 0.02) | 0.14 (−1.07 to 1.35) | 0.59 (−0.17 to 1.32) | 0.34 (−5.69 to 6.37) | 0.24 (−0.44 to 0.92) |
| CHCl2Br to exhaled breath (μg/m3) | 0.14 (−0.77 to 1.06) | −0.43 (−2.60 to 1.73) | 0.00 (−0.01 to 0.02) | 0.22 (−0.66 to 1.10) | 0.43 (−0.13 to 0.99) | 0.87 (−3.50 to 5.25) | 0.55 (0.08 to 1.02)* |
| CHClBr2 to exhaled breath (μg/m3) | −0.05 (−1.79 to 1.69) | −1.07 (−5.18 to 3.03) | 0.01 (−0.02 to 0.03) | 0.22 (−1.43 to 1.88) | 0.71 (−0.29 to 1.70) | 1.06 (−7.22 to 9.35) | 1.92 (1.19 to 2.67)** |
| CHBr3 to exhaled breath (μg/m3) | 0.35 (−0.97 to 1.65) | −0.05 (−3.16 to 3.06) | 0.00 (−0.02 to 0.02) | −0.07 (−1.53 to 1.38) | 0.32 (−0.41 to 1.05) | 3.13 (−3.09 to 9.30) | 1.21 (0.59 to 1.82)** |
| TTHMs to exhaled breath (μg/m3) | 0.31 (−0.79 to 1.44) | 0.17 (−2.49.2.81) | 0.00 (−0.02 to 0.02) | 0.17 (−0.93 to 1.24) | 0.54 (−0.12 to 1.20) | 0.76 (−4.57 to 6.10) | 0.59 (0.02 to 1.18)* |
| Energy expenditure (kcal) | −0.65 (−2.03 to 0.73) | −2.97 (−6.10 to 0.17) | 0.02 (−0.00 to 0.04) | 0.20 (−1.14 to 1.54) | 0.98 (0.22 to 1.74)* | 0.85 (−5.73 to 7.41) | 1.04 (0.37 to 1.73)** |
Abbreviations: CHBr3, bromoform; CHClBr2, dibromochloromethane; CHCl2Br, bromodichloromethane; CHCl3, chloroform; NHCl2, dichloramine; TTHMs, total THMs. Percent predicted refers to percentage of that predicted by age to sex to and height. SP-D and CC16 were measured in serum. 8-Isoprostane was measured in EBC.
Wilcoxon test.
β-Coefficients from linear regression models represent a change in the biomarker level for an increase from 25th to 75th percentile of the exposure parameter. FeNO models are adjusted for rhinitis; 8-isoprostane models are adjusted for usual swimming pool attendance. The other models are crude.
p < 0.05.
p < 0.01.