| | Heavy metal | Source |
| | Pb | Gasoline additives, ammunition, solder, paint, pesticide | | Hg | Electrical manufacturing, pharmaceuticals, paints, plastics, paper, batteries, coal, mercury smelters, and mercury preparation plants | | Cd | Plastic, enamels with pigment, electroplating, metal covering | | Cr | Mine, smelting plant, electroplating factory, chrome tanning system | | As | Atmospheric dust, tailings and pesticide, leather, chemical pharmaceutical, metallurgy, decolorant | | Cu | Mine, metal processing, machinery manufacturing, steel production | | Zn | Galvanizing, smelting, machinery manufacturing, organic synthesis, mine |
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