Cadmium in the Environment: Emphasis on Water
Gloria Benzakarya, Delia Ponce and Antonio F. Machado
Department of Environmental & Occupational Health, CSUN
Abstract:
Cadmium, a heavy metal that is naturally present in the environment is also used in various industrial processes. This metal
is an occupational and environmental concern. Cadmium depending on the route and the level of exposure may cause
detrimental health effects that are irreversible. There are many different sources that can pollute the environment. Based
on our findings we conclude that monitoring of Cd levels need not be only in water, but also in the cultivation on soil , the
emissions that go into the air. etc. The current literature review is to evaluate cadmium toxicity to humans from water.
Introduction
What is Cadmium?
 Cadmium (Cd) is a metal that is found naturally in the
earth’s crust but is also derived from industrial processes.
 Most commonly found in the environment in combination
with other elements such as oxygen, chlorine, and sulfur.
What is Cadmium used for?
 Cd is used in metal plating and coating for the manufacture
of pigments, batteries, & plastics.
 In the US, Cd exists mainly as a byproduct of such practices.
How are humans exposed to it?
 Exposure can happen through inhalation of Cd from the
burning of fossil fuel, eating Cd contaminated foods,
drinking Cd containing water, and cigarette smoking.
 Corrosion of galvanized pipes, runoff from waste batteries
and paint & discharges from metal refineries lead to the
contamination which can get into our water system.
Why is Cadmium a concern?
 Cd can cause health effects to humans such as kidney , liver
and lung damage. The kidneys & liver contain about 50% of
total Cd accumulation in the body. 1
 Growing concern is associated with long term exposure at
low doses due to its long biological half life. The half life can
be anywhere between 4-38 years. 1
Origin of cadmium:
Cadmium is naturally occurring in the Earth’s crust from
underlying bedrock. Sedimentary rocks have the highest cadmium
levels; levels have been reported to be up to 25 ppm. However,
most cadmium in the environment is a byproduct of industrial
practices some of which are listed below. 6
Source
Fertilizers
Fossil Fuels
Natural Sources
Iron and Steel Production
Cement and Others
Nonferrous Metals
Production
Cadmium Products
Waste Incineration
Levels
33%
21%
20%
12%
7%
4%
2%
1%
www.cadmium.org
http://en.wikipedia.org/wiki/Cadmium
Remediation
Methods used to remove Cd from water4:
 Coagulation/Filtration
 Salts (aluminum or iron) are added to the water which
then bind with Cd to form larger particles that can more
easily settle out of the water and/or filtered out more
effectively.
 Ion exchange
 Works by replacing the Cd(II) ion by another ion which is
considered less harmful.2
 This method is considered to be highly efficient.
Studies performed on industrial wastewater have
resulted in 99.9% extraction. 3
Cadmium in the Environment
Naturally Occurring
Levels
Earth’s crust
0.1-.5 ppm1
Ocean
<5 and 110 ng/L1
Surface/groundwater
<1µg/L1
Water
 Cd is leaked into the water from the leaching of
landfills, sewage discharge, and the piping in the
distribution system.
 Higher levels of Cd are found in coastal areas.
 Largest source of Cd emissions to water from man
made practices are from the smelting of nonferrous
metal ores1
 Agricultural run-off is of major concern in areas that
are in close proximity to farming because of the types
of fertilizers being used to grow crops.
 Amongst the food that have a high Cd content is
shellfish, oysters, and scallops. This is attributed to
the Cd levels that contaminate the waters they live in
as well as the bioaccumulation factors of these fish.4
Soil
 Cd concentrations vary depending on how the soil is
being cultivated and the location of the land.
 Phosphate fertilizers added to soil can contain up to
300 mg Cd/kg.1
 Atmospheric deposition and sewage sludge disposal
are additional ways Cd infiltrates the soil.
Air
 Cd is found at different concentrations in ambient air,
occupational environments, and from Tobacco
smoke.
 Concentrations vary from 0.1-5ng/m31
 1 cigarette contains .5-2μg of Cd; 10% is inhaled1.
 Aside from industrial practices, Cd is released in the
air through volcanic eruptions, forest fires, and may
also be released from sea salt aerosols.
 Lime softening
 Helps to settle out the contaminated water by the
addition of calcium hydroxide.
 Reverse osmosis.
 Water is put through a semipermeable membrane.
 Efficiency is dependent on solute concentration,
pressure, and water flux rate.
Regulations:
Drinking Water • The EPA has determined that exposure to Cd in drinking
water at a concentration of 0.04 mg/L for up to 10 days is
not expected to cause any adverse effects in a child.
• The EPA has determined that lifetime exposure to .005 mg/L
cadmium in drinking water is not expected to cause any
adverse health effects.
Bottled Water
• The FDA has determined that cadmium levels in bottled
water should not exceed .005 mg/L.
Workplace Air
• OSHA set a legal limit of 5µg/m3 cadmium in air averaged
over an 8 hour work day.
http://www.atsdr.cdc.gov/phs/phs.asp?id=46&tid=151
In California,
Fate and Transport:
Water: About 2,346 pounds of cadmium compounds are
released to surface water, the ocean has about 110 ng of
cadmium. When cadmium is released into the water, it effects
the ecosystem. The heavy metal is easily absorbed by fish and
other aquatic organisms. Thus the cadmium bio-accumulates in
fish and the levels increase as the trophic level increases and
humans that consume fish become exposed to significant
levels of cadmium, which in turn becomes a human exposure if
the fish are consumed. 8
Aqueous cadmium is not influenced in water, and the potency
stays the same. However, under reducing conditions, cadmium
may form cadmium sulfide, which is not soluble and usually
precipitates. Ionic cadmium seems to be the toxic form and
becomes more predominant at low levels of salt.
Air: Small particles of cadmium are transported from a
hundred kilometers and have a typical atmospheric residence
time of about 1-10 days before it deposits again. This process
complicates cadmium pollution. 7
Soil: When the soil is contaminated with cadmium, the plants
ingest the cadmium and other animals eat it which also causes
bioaccumulation. 9 The Cd accumulation of the plants occurs
mostly in the leaves. Which can be further damaging to
humans who consume leafy vegetables. 1
References:
Disposition and Metabolism:
The metabolism of cadmium involves:
Cd being transported to the liver inducing the creation of
metallothionein, a low molecular weight metal-binding protein.
Cadmium becomes bound to this protein, forming a metal-protein
complex which is then released back to the blood and transported
to the kidney .10
The excretion of Cadmium:
Cd is excreted from the human body by going through the
kidneys and liver, which accumulates for many years. A small
portion of cadmium is excreted through urine and feces over a
long period of time. 11
Contaminant in Water
MCL
PHG
mg/L
Cadmium
0.005
0.00004
http://cdph.ca.gov/certlic/drinkingwater/Pages/MCLReview2011.aspx
5
Significance given to Cd:
 The EPA has classified Cd as a probable human carcinogen (Group
B1). 4
 Cd ranks #7 on the ATSDR 2013 Substance Priority List with a score of
1318.71
In conclusion…
The regulations for Cd levels in drinking water are sufficient to
maintain human intake at low levels. The problem associated with this
contaminant, as with many others, is a dynamic issue. Contamination is
not merely associated with one source. Levels of contamination depend
on the many variables unique to a particular area. Cd emissions that
affect the air, soil, water, food, and atmosphere all will interact and
accumulate differently based on factors such as location, temperatures,
and pH levels of different media.
The highest Cd exposure to humans are known to come from Cd
Health Effects:
contaminated food, not the drinking water (1). Therefore, a closer look
This depends on the route of exposure and the dose, but since the main should be taken at the way crops are being grown. For example, more
concern is through oral exposure from drinking water, then chronic
stringent regulations need to be established for the types of fertilizers
exposure would be the main concern and cause the following:
that are being used. Location of where the crops are being grown need to
• Itai-Itai is a disease that is coined in Japan that literally mean “ouch- also be considered to determine if waste sludge, runoff or any other near
ouch,” and it consists of severe pain in the bone, joint, and muscle.
by industrial processes are adding to the Cd concentration of plants. This
This disease is also coupled with eventually having loss of kidney
will avoid not only the crops from accumulating high levels of Cd, but the
function
animals who are perhaps feeding on these plants (which humans may
• Hematuria is a condition in which red blood cells are present in
eventually eat) will also benefit from lower Cd exposures.
urine. This is an indicator of kidney damage and results in anemia.
To avoid further contamination of ground water, alternatives to Cd
• Cancer of the breast, kidney and pancreas, and urinary bladder is
containing batteries, for example, should also be sought. This will avoid
caused by long-term exposure to cadmium. 12
the leaching of Cd from landfills into the ground.
1. Agency for Toxic Substances & Disease registry. Cadmium Profile. http://www.atsdr.cdc.gov/toxprofiles/TP.asp?id=48&tid=15
2. Da̧browski, A, Z Hubicki, P Podkościelny, and E Robens. "Selective Removal of the Heavy Metal Ions from Waters and Industrial Wastewaters by Ion-exchange Method." Chemosphere, 56.2 (2004): 91-106.
3. Al-Enezi, G, MF Hamoda, and N Fawzi. "Ion Exchange Extraction of Heavy Metals from Wastewater Sludges." Journal of Environmental Science and Health Part A-toxic/hazardous Substances & Environmental Engineering, 39.2 (2004): 455-464.
4. United States Environmental Protection Agency. http://water.epa.gov/drink/contaminants/basicinformation/cadmium.cfm
5. http://cdph.ca.gov/certlic/drinkingwater/Pages/MCLReview2011.aspx
6. "All the Information on Cadmium." All the Information on Cadmium. ICdA North America, n.d. Web. 11 Dec. 2014.
7. Toxicological Profile for Cadmium. Atlanta, GA: U.S. Dept. of Health and Human Services, Public Health Service, Agency for Toxic Substances and Disease Registry, 1993. Web.
8. Communities, Environment And. Impacts of Metals on Aquatic Ecosystems and Human Health (n.d.): n. pag. Web.
9. "Result Filters." National Center for Biotechnology Information. U.S. National Library of Medicine, n.d. Web. 13 Dec. 2014.
10. "Section 5 - V. Health Effects." Section 5 - V. Health Effects. N.p., n.d. Web. 14 Dec. 2014.
11. "A-Z Index." ATSDR. N.p., n.d. Web. 14 Dec. 2014.
12. "Result Filters." National Center for Biotechnology Information. U.S. National Library of Medicine, n.d. Web. 14 Dec. 2014.