Trace elements | Total average valuesa | Local background limit valuesa | UCCb | Chinac | Japan | Canada |
Cr | 79 | 89.8 | 35 | 200 | - | 75 |
Co | 16 | 9.9 | 11.60 | 40 | 50 | 250 |
Ni | 181 | 74.8 | 18.60 | 50 | 100 | 100 |
Cu | 193 | 81.9 | 14.30 | 100 | 125 | 100 |
Zn | 37 | 42.92 | 52 | 52 | 250 | 400 |
As | 4 | 6.75 | 2 | 25 | - | 200 |