| Heavy metals | Average | Range |
| Cadmium (Cd) | 5 | 0.01 - 0.70 |
| Copper (Cu) | 20 | 2 - 100 |
| Chromium (Cr) | 200 | 5 - 1000 |
| Lead (Pb) | 10 | 2 - 200 |
| Zinc (Zn) | 50 | 1 - 300 |