| GST | Allelic variants | Professional motorcycle drivers N (%) | Non-professional motorcycle drivers N (%) | 95 % IC | P-value |
| GSTM1 | Present | 09 (30) | 18 (60) | −0.59 - 0.00 | 0.04 |
| Absent (Null) | 21 (70) | 12 (40) | 0.10 - 1.23 | 0.02 | |
| GSTT1 | Present | 06 (20) | 07 (23) | −0.26 - 0.19 | 0.76 |
| Absent (Null) | 24 (80) | 23 (77) | −0.39 - 0.52 | 0.76 | |
| GSTM1 Null/GSTT1 Null | 17 (57) | 10 (33) | −0.71 - 0.08 | 0.01 | |