| Heavy metal (µg/g) | Samples from the South Eastern region | Samples from the North Central region | F test p value | [28] STD |
| Pb | 0.24 ± 0.02 | 0.15 ± 0.08 | 0.02 | 0.5 |
| Cd | 0.01 ± 0.00 | - | 0.01 | 0.02 |
| Cu | 0.78 ± 0.10 | 1.12 ± 0.16 | 0.01 | 2.00 |