Nanoparticles as Sorbents for Removal of Heavy Metal Ions from Aqueous Solutions - Nanotechnologies for Water Environment Applications - page 138

Table 6.1 Heavy metals of industrial and ecological significance and their WHO
guideline values for drinking water quality regulation (WHO, 2006).
Heavy
Metals

Values
(mg/L)

Origins in Industry &
Consumer Products

Remarks

Arsenic
- As(III),
As(V)

0.01 (P) Alloying agents in

manufacturing transistors and
semiconductors.

Most often introduced into drinking water
sources via groundwater pollution due to
dissolution of natural occurring minerals/ores.

Cadmium
- Cd(II)

0.003 Steel, plastics, batteries and

artificial fertilizers.

Major release routes to the environment are
via the use of fertilizers and from air
pollution.

Chromium
- Cr(III),
Cr(VI)

0.05 (P) Leather tanning, pigments

and paints, fungicides,
chrome alloy and metal
production, corrosion control.

Widely distributed in the earth's crust.
Environmental pollution by Cr is mostly due
to industrial activities. The distribution
between Cr(III) and Cr(VI) is highly
dependent on the redox potential and its
kinetics, as well as the pH. Toxicology study
shows that Cr(VI) is carcinogenic.

Copper
- Cu(II)

2 Pipes, valves and fittings,

copper alloy metal
production and coating,
electroplating.

Copper occurrence in drinking water is
mostly caused by corrosion in water
distribution systems, especially with acid pH
or high-carbonate waters with alkaline pH.

Lead
- Pb(II)

0.01 Lead-acid batteries, solder

and alloy metal production,
antiknock and lubricating
agents in petrol.

The presence of lead in tap water is often
caused by plumbing systems containing lead
in pipes and fittings.

Mercury
- Hg(I),
Hg(II)

0.006 Chlorine and caustic soda

production, dental amalgams,
electric appliances,
antiseptics and fungicides,
gold mining.

The major contamination by Hg is due to
either industrial activities or catastrophic
release. Major human exposure pathway is
ingestion of fish products from where local
water is contaminated.

Nickel
- Ni(II)

0.07 Stainless steel and nickel

alloys, electroplating,
catalyst, welding and
electronic products.

Major source of Ni in drinking water is
passive leaching from stainless steel pipes and
fittings. Contamination of groundwater by Ni
is from dissolution of Ni-containing ores.

Not of health concern at concentrations
normally observed in drinking-water.
Contamination in tap water is mostly due to
the leaching from pipes and fittings.
* Provisional guideline value (P) is designated as there is evidence of hazard, but the available
information on the health effects is limited.

Zinc
- Zn(II)

3 Alloy metal production,

pigment powder and
pesticides.