| TITLE |
Cobalt
(Co) |
| GENERAL
INFORMATION |
Cobalt
is an essential element. The only known function is as an
integral part of vitamin B12 (Cobalamin) which is essential
for folate and fatty acid metabolism (1).
Cobalt is obtained primarily as a by-product of the mining
and processing of copper and nickel ores. Cobalt compounds
are used mainly as oxidation catalysts in chemical reactions
and pigments in the production of glass and ceramics.
The
absorption rate by the lungs and GI tract is dependent on
the solubility of Co compounds. About 30% of Co inhaled
as Co oxide can be absorbed and the oral absorption rate
varies from 5 to 45%. Cobalt is mainly excreted in urine;
most being eliminated rapidly (a few days), with a small
fraction eliminated slowly (a couple of years) (2).
|
SOURCES/ROUTE
OF EXPOSURE
|
Cobalt
is normally associated with copper or nickel. The major sources
of environmental cobalt include mining and smelting of cobalt-bearing
ores, the use of cobalt-containing sludge or phosphate fertilizers
on soil, and the disposal of cobalt-containing waste. Occupational
exposure to Co occurs mainly by inhalation of fumes and dusts
containing cobalt.
Dietary
sources include meats, fish, cheese and brewer's yeast and
yeast extracts.
Cobalt is also added in multivitamin pills.
|
| TOXICITY |
In
the past, Co salts used to be added to beer as foam stabilizers
which lead to an epidemic of cardiomyopathy among heavy beer
drinkers. Cobalt and alcohol may have an additive effect in
reducing coronary blood flow and thus causing anoxia and damage
to the heart muscle (1, 3). |
| MONITORING/CLINICAL
INTERPRETATION |
Cobalt
deficiency is not a major problem in humans as long as the
body has sufficient amounts of vitamin B12 (1).
Individuals
with metallic prostheses made from cobalt and chromium may
have significantly elevated concentrations of cobalt and
chromium in blood and urine due to wear and corrosion of
orthopaedic implants. The clinical significance of elevated
metal ion levels has not been fully understood. However,
evidence has shown that highly elevated blood levels are
probably associated with high wear at the bearing, implant
dysfunction, and adverse tissue reactions to metal debris.
UK
MHRA Threshold for individuals with metallic hip replacement
(4)
Cobalt in blood: 7 ug/L (118.8 nmol/L)
ACGIH
Biological Exposure Index (5)
Cobalt in blood (end of shift at end of workweek): 1 ug/L
( 16.97 nmol/L)
Cobalt in urine (end of shift at end of workweek): 15 ug/L
(254.5 nmol/L)
|
| MATRIX
CHOICE |
Analysis
of Co in urine samples collected at the end of the work week
is recommended for assessing exposure to soluble cobalt compounds.
For
metal ion analysis following orthopedic arthroplasty, whole
blood is the recommended sample because it does not need
to be separated or transferred into a secondary tube after
draw, and the primary collection tube can be sent directly
for testing. This avoids possible sample contaminations
from additional sample process steps.
If urine
is to be tested, 24 hour urine is the preferred sample.
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| TREATMENT |
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| REFERENCES |
1.
http://www.food.gov.uk/multimedia/pdfs/evm_cobalt.pdf
2. Industrial Chemical Exposure. Guidelines for Biochemical
Monitoring, Robert Lauwerys and Perrine Hoet, 3rd Edition,
2001
3. WHO International Programme on Chemical Safety (IPCS).
Concise International Chemical Assessment Document 69. Cobalt
and Inorganic Cobalt Compounds. 2006
4. Metal-on-metal hip replacement and hip resurfacing arthroplasty.
What does the MHRA medical device alert mean? http://www.jisrf.org/pdf_files/MoM_BOA-BHS_AdvicetoSurgeons_1.pdf
5. ACGHI (American Conference of Governmental Industrial Hygienists).
Threshold Limit Values for Chemical Substances and Physical
Agents & Biological Exposure Indices, 2008 |
TEST
INFORMATION/
REFERENCE RANGES
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