| Country | Pb | Cd | Cr | Cu | Zn | Ni |
| Germany | 70 | 1 | 60 | 40 | 150 | 50 |
| Poland | 100 | 3 | 100 | 100 | 300 | 100 |
| UK | 450 | 10 | 130 | - | - | 130 |
| Australia | 300 | 3 | 50 | 100 | 200 | 60 |
| Taiwan | 300 | 5 | 250 | 200 | 600 | 200 |
| Bulgaria | 26 | - | 65 | 34 | 88 | 46 |
| Canada | 200 | 3 | 250 | 150 | 500 | 100 |
| China | 80 | 1 | 200 | 100 | 250 | 50 |
| Tanzania | 200 | 1 | 100 | 200 | 150 | 100 |
| FAO/WHO | 100 | 3 | 100 | 100 | 300 | 50 |
| E.U. Guidelines | 300 | 3 | 150 | 140 | 300 | 75 |
| South Africa | 20 | 8 | 7 | 16 | 240 | 91 |
| Nigeria (D.P.R.) | 35 | 100 | 20 | - | - | 140 |
| This study | 18.5 - 8611 | 2.7 - 37.1 | 9.1 - 28.8 | 24.1 - 23174 | 148 - 9078 | 12 - 157.9 |