Table 1.
Sources, toxicity and permissible limit of heavy metals by USEPA
| Heavy metals | Anthropogenic Sources | Toxic effect | Permissible limit (drinking water) |
|---|---|---|---|
| Arsenic (As) | Metal processing, mining sites, timber storage, coke ovens emission, pesticide and fertilizer industries. | Accumulates inside the cell, Carcinogen | 0.05 mg/L |
| Chromium (Cr) | Fertilizers, fossil fuels burning, oil drilling sites, metal tanneries and plating industries. | Group 1 human carcinogen |
0.05 mg/L |
| Cadmium (Cd) | Phosphate fertilizers, battery, and plating industries. |
Nephrotoxicity and Carcinogenicity, affect gastrointestinal and pulmonary tract | 0.005 mg/L |
| Mercury (Hg) | Battery industries, pig iron, caustic soda, gold, and cement production | Chromosome breakage, bronchitis asthma and Hunter–Russell syndrome |
0.002 mg/L |
| Nickel (Ni) | Electroplating industries |
Eczematous reaction |
0.1 mg/L |
| Copper (Cu) | Electroplating industries |
Kidney damage, anemia |
1.3 mg/L |
| Selenium (Se) | Mining, agricultural irrigation |
Bronchitis, gastrointestinal disturbances |
0.05 mg/L |
| Lead (Pb) | Mining, batteries, use of lead products | Crosses the blood–brain barrier, carcinogenic, neurodegeneration | 0.05 mg/L |
| Iron (Fe) | Metal refining, engine parts. | Seizures or coma. | 0.3 mg/L |
| [32,33,42,43] | |||