Table 5.
Comparison of the pre-employment and current pulmonary functions of the silica-exposed workers with different severity of exposure.
| Parameters | Control group | Intensity of exposure∗ |
||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Group 1 Exposure > TLV-TWA† (n = 85) |
p-value | Group 2 TLV-TWA† < Exposure ≤5 TLV-TWA† (n = 102) |
p-value | Group 3 Exposure <5 TLV-TWA† (n = 194) |
p-value | |||||
| Pre-employment (2009) | Current (2019) | Pre-employment (2009) | Current (2019) | Pre-employment (2009) | Current (2019) | |||||
| FVC | 96.52 ± 7.18 | 100.3 ± 12.1 | 93.8 ± 6.9 | 0.3 | 99.3 ± 13.4 | 92.5 ± 7.5 | 0.007 | 99.3 ± 13.2 | 93.3 ± 7.6 | 0.01 |
| FEV1 | 96.99 ± 8.03 | 100.3 ± 11.2 | 92.2 ± 8.1 | 0.5 | 100.5 ± 12.4 | 92.4 ± 7.2 | 0.006 | 98.8 ± 13.4 | 90.9 ± 8.4 | 0.005 |
| FEV1/FVC | 100.62 ± 6.81 | 100.4 ± 8.3 | 98.4 ± 6.3 | 0.1 | 101.4 ± 5.9 | 100.1 ± 5.9 | 0.7 | 99.8 ± 8.9 | 97.5 ± 6.2 | 0.3 |
| PEF | 101.5 ± 10.77 | 103.6 ± 16.2 | 99.4 ± 8.4 | 0.7 | 102.2 ± 12.2 | 99.8 ± 8.9 | 0.1 | 99.7 ± 18.5 | 97.2 ± 9.8 | 0.5 |
∗
Based on the TWA exposure: group 1: 0.017 mg/m3 (001–0.019); group 2: 0.089 mg/m3 (002–0.095); group 3: 0.24 mg/m3 (010–0.29). Durations of exposure: group 1: 11.81 ± 6.84; group 2: 9.87 ± 6.39; group 3: 6.54 ± 5.18 years.
†
12-h TLV-TWA for silica: 0.019 mg/m3. FVC: forced vital capacity; FEV1: forced expiratory volume in the first second; PEF: peak expiratory flow. TLV-TWA: threshold limit value-time weighted average for silica dust proposed by the ACGIH.