Table 3.
Potential sources of contamination for toxic metals and metalloids included in study.
| Metal/Metalloid | Potential Sources of Contamination | |||
|---|---|---|---|---|
| Naturally Occurring | Catchment Pollution | Treatment and Distribution | ||
| Industrial | Human Settlements | |||
| Antimony | X | X | X | |
| Arsenic | X | X | ||
| Cadmium | X | X | X | |
| Chromium | X | X | ||
| Copper | X | X | X | |
| Iron | X | X | X | |
| Lead | X | X | X | |
| Manganese | X | X | ||
| Mercury | X | |||
| Nickel | X | X | X | X |
| Selenium | X | X | ||
| Tin | X | X | ||
| Uranium | X | X | ||
| Zinc | X | X | X | |
Adapted from the World Health Organization. Guidelines for drinking-water quality: First addendum to the fourth edition, WHO: Geneva, Switzerland, 2017 and Thompson, T.; Fawell, J.; Kunikane, S.; Jackson, D.; Appleyard, S.; Callan, P.; et al. Chemical safety of drinking water: assessing priorities for risk management, WHO: Geneva, Switzerland, 2007.