Table 1.
Baseline characteristics of study participants
| Parameters (unit) | Toner-handling group | Non-toner-handling group | P-value | ||
|---|---|---|---|---|---|
| n = 887 | n = 581 | ||||
| M (SD)/% | M (SD)/% | ||||
| Age (years) | 38.7 | (7.1) | 38.5 | (6.5) | 0.678 |
| BMI (kg/m2) | 23.3 | (2.9) | 23.7 | (2.9) | 0.023 |
| Current smoker | 51.2% | 46.8% | 0.109 | ||
| Prevalence of respiratory diseases (%) | |||||
| Asthma | 9.5% | 10.3% | 0.591 | ||
| Allergic rhinitis | 51.1% | 48.2% | 0.286 | ||
| Allergic dermatitis | 20.9% | 22.2% | 0.558 | ||
| Pneumonia | 0.5% | 0.3% | 1.000 | ||
| Sinusitis | 2.7% | 1.9% | 0.383 | ||
| Ratio of workers handling harmful substances (%) | |||||
| Workers handling dust other than toner | 2.9% | 0.3% | < 0.001 | ||
| Workers handling organic solvent | 26.3% | 2.9% | < 0.001 | ||
| Respiratory function test indicators | |||||
| VC (l) | 4.2 | (0.6) | 4.2 | (0.6) | 0.390 |
| %VC (%) | 92.4 | (10.7) | 91.8 | (9.8) | 0.307 |
| FEV1 (l) | 3.5 | (0.5) | 3.5 | (0.5) | 0.521 |
| %FEV1 (%) | 95.0 | (11.2) | 94.5 | (10.8) | 0.412 |
| FEV1/FVC (%) | 83.1 | (5.9) | 82.9 | (6.0) | 0.655 |
| %FEV1/FVC (%) | 100.1 | (6.9) | 100.1 | (7.1) | 0.938 |
| V25 (l/s) | 1.6 | (0.5) | 1.6 | (0.5) | 0.940 |
| %V25 (%) | 68.2 | (19.9) | 67.4 | (18.7) | 0.413 |
| Biomarkers | |||||
| CRP (mg/dl) | 0.09 | (0.18) | 0.10 | (0.21) | 0.455 |
| IgE (IU/ml) | 201.6 | (380.3) | 219.9 | (436.6) | 0.424 |
| IL-4 (pg/ml) | 19.2 | (29.4) | 10.8 | (31.1) | < 0.001 |
| IL-6 (pg/ml) | 1.40 | (3.20) | 1.20 | (4.70) | 0.412 |
| IL-8 (pg/ml) | 2.90 | (19.90) | 1.10 | (0.80) | 0.017 |
| IFN-γ (IU/ml) | 0.11 | (0.01) | 0.07 | (0.07) | < 0.001 |
| 8-OHdG/Creatinine (ng/mg) | 3.90 | (1.50) | 3.80 | (1.4) | 0.357 |
M mean, SD standard deviation, BMI body mass index, VC vital capacity, %VC percentage of VC to predicted VC value, FEV1 forced expiratory volume in 1 s, %FEV1 percentage of FEV1 to predicted FEV1 value, FEV1/FVC percentage of forced expiratory volume in 1 s, %FEV1/FVC percentage of FEV1/FVC to predicted FEV1/FVC value, V25 maximal expiratory flow at 25% forced VC, CRP C-reactive protein, IgE immunoglobulin E, IL interleukin, IFN-γ interferon-gamma, 8-OHdG 8-hydroxy-2′-deoxyguanosine