| Variable | Hairdressers | Control | p-value |
| Mean concentrations of urinary p-PDA ( | 17.37 ± 1.35 | 1.92 ± 0.17 | <0.0001 |
| Variable | Hairdressers | Control | p-value |
| Mean concentrations of urinary p-PDA ( | 17.37 ± 1.35 | 1.92 ± 0.17 | <0.0001 |
± SD) (ng/ml)