Table 2.

Sources and permissible limits of Cd [49–52].

Natural Sources	Industrial Sources	Uses	Permissible limit (mg L−1)
Coal combustion, iron and steel production, phosphate fertilizer manufacture and use, and zinc production, volcanic activities	Zinc smelting, mining, waste batteries, e-waste, fuel combustion, manufacturing of alloys, pigments and dyes, textile operations etc.	Electroplating of steel, Ni-Cd batteries, cellular telephones, Laptop computers and camcorders	0.003 (IS 10500) 0.003 (WHO) 0.005 (USEPA) 0.005 (EU Standard) 0.002 (NHMRC, Australia)