| Parameters | Author and Sampling Date | Maximum Permissible Limit (EPA, 2003) | |||
| Zinabu and Pearce, 2003 (Nov. 1995) | Zinabu and Pearce, 2003 (Mar. 1996) | Abay, 2007 (Nov. 2006 to March 2007) | Present Work (Dec 10, 2009) | ||
| Co | 0.3 | ND | - | 10.7 | 1000 |
| Cr | 17.7 | 22 | 120 | 2.3 | 1000 |
| Pb | 0.4 | 2.4 | 160 | 28.1 | 500 |
| Cd | 1.6 | ND | 30 | 0.12 | 1000 |
| Zn | 8.9 | 163 | 40 | 41000.0 | 5000 |
| Fe | 131.9 | ND | 1230 | 1500 | 1000 |
| As | 10.6 | 9.4 | - | 0.69 | 250 |
| Hg | 3.8 | ND | - | 0.32 | 1.0 |