1. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Is f a h a n U n iv e r s it y o f M e d ic a l S c ie n c e , S c h o o l o f P h a r m a c y
D e p a r t m e n t o f C lin ic a l B io c h e m is t r y
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2. C a d m iu m
B io lo g y
(An
O v e r v ie w )
B y: A .N . E m a m i
3. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Outlines
Introduction
Pharmacokinetics
Molecular mechanism of toxicity
Pathogenesis effects
Detoxification
Summery
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5. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
silver ← cadmium → indiumn
Zn
↑
Cd
↓
Hg
Periodic Table - Extended Periodic Table
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6. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Cadmium:
A Co-product of Zinc Smelting
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7. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Notable characteristics
Cadmium is a soft, malleable, ductile, toxic, bluish-white
bivalent metal. It is similar in many respects to zinc but
reacts to form more complex compounds.
The most common oxidation state of cadmium is +2, though
rare examples of +1 can be found.
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8. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Properties of cadmium
Boiling point=765° C
Melting point=320.9° C
Silvery metal soft enough
to be easily cut with a
knife
Density=8.65g/cm³
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9. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Cadmium facts
Date of discovery = 1817
Discoverer = Fredrich Stromeyer
Atomic number = 48
Atomic mass = 112.41
1776 - 1835
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10. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Sources:
Natural rock weathering
Copper, lead and zinc smelting auto exhaust
Cigarette smoke (a cigarette contains 1-2 ug Cd)
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11. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Small rocks - Cadmium (Cd)
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12. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Cadmium base, Cd
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13. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Industrially produced cadmium
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14. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Cadmium sifide
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15. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Cadmium smithsonite contains cadmium impurities and is
yellow to yellow-green.
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16. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
The Name 'Smithsonite
Smithsonite was named after James
Smithson in 1832. James Smithson was an
English scientist, often referred to as the best
chemist and mineralogist of his year. He
was an active member of many scientific
organizations that benefited society and
advanced scientific research. James
published at least 27 papers with topics in
chemistry, geology, and mineralogy. In
1802 James Smithson proved that zinc
carbonates were true carbonate minerals, not
zinc oxides. This discovery lead to the
breakdown of calamine into two separate
minerals hemimorphite and smithsonite.
After James Smithson's death in 1829 the
bulk of his estate was given to his nephew.
Since his nephew died without any heirs the
Smithson Estate was then given to the
United States of America to found the
Smithsonian Institution.
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17. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Cadmium Production
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18. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Cadmium Consumption
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19. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
The Application of Cadmium
metal plating
nickel-cadmium batteries
solders
paint pigments
plastic stabilizers
photographic chemicals
fungicides
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20. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Cadmium Plating
COMMERCIAL
Cadmium has long been used for its superior corrosion protection.
Cadmium as deposited is bright silver finish to which a clear or yellow
chromate can be applied. The deposit is soft, ductile and solderable. Here
at DeTray Plating Works we have both rack and barrel capabilities
depending on your needs.
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21. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
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22. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
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23. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
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24. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Nickel Cadmium Batteries
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25. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Cadmium in paints
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26. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Chrome yellow and Cadmium yellow
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27. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
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28. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
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29. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Cadmium Orange Poppies Art Print
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30. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
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32. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Inhalation
Smelters, cigarette smoke
15-50% absorbed
Shenyang Copper Smelter
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33. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Cigarette smokers, however, typically
sustain significantly higher exposure.
Cadmium inhaled through cigarette
smoke is more easily taken up by the
body than cadmium in food or water.
From 40 to 60 percent of the cadmium
inhaled in smoke is absorbed into the
bloodstream as opposed to the 5 to 10
percent absorbed through foods. Each
cigarette contains roughly 1 to 2
micrograms of cadmium, and smokers
absorb an additional 1 to 3 micrograms
of cadmium into their systems daily
for every pack they smoke. Studies
have shown that smoking more than
20 cigarettes daily can increase
cadmium levels in the body tenfold.
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34. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Ingestion
Main source is liver and
kidney of meats
6% absorbed, greater if
deficient in calcium, zinc
or iron
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35. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Distribution
bound to albumin in plasma
and red blood cells
transported to liver,
pancreas, prostate and
kidney, with eventual
transfer to kidney
50-75% of total body Cd is
found in liver and kidney
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36. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Metallothionein
protein rich in cysteine
Traps Cd esp. in kidney
Synthesis induced by Cd
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37. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Elimination
Urine
half-life in humans is 20 - 30 years
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38. C a d m iu m
M o l e c u l a r m e c h a n is m
o f t o x ic it y
39. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Classification of metals
Class A Borderline Class B
(oxygen-seeking) (sulphur- or nitrogen-
seeking)
Calcium Zinc Cadmium
Magnesium Lead Copper
Iron Mercury
Manganese
Chromium Silver
Potassium Cobalt
Strontium Nickel
Sodium Arsenic
Vanadium
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40. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Borderline and Class B metals and
metalloids are important pollutants
Nitrogen- and sulphur-seeking
High affinity to proteins and other biological ligands
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41. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Cadmium is a heavy metal
Heavy metals are chemical elements that have
a specific gravity (a measure of density) at
least five times that of water.
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42. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Basis of toxicity of metals
Substitution of essential metals in active centers of enzymes
Interference with intracellular signaling pathways and Ca2+
metabolism
Oxidative stress (excessive production of free radicals)
Interference with DNA transcription, translation and repair
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43. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Toxic effects of heavy metals
Heavy metals (HM) exert their toxic effects by combining
with one or more reactive groups (ligands) essential for
normal physiological functions
Nearly all organ systems are involved in heavy metal toxicity;
however, the most commonly involved organ systems include
the CNS, PNS, GI, hematopoietic, renal, and cardiovascular
(CV).
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44. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Mechanisms of uptake and transport
of metals
Lipid route
Plays limited role in metal transport
Hg may diffuse through the membrane in the form of neutrally charged
chlorocomplexes
Hg2++2Cl- ↔ HgCl2
Aqueous routes
Simple diffusion
Yes
Facilitated diffusion
Very much so
Active transport
Little or no role
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45. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Simple and facilitated diffusion
Ion channels
Ca2+ channels
can transport Zn2+, Cd2+, Hg2+, Pb2+
SH-rich Zn2+ channels
can transport Cd2+
Carrier proteins
Divalent cation transporter 1 (DCT1)
Major carrier protein for uptake of Fe2+, Zn2+ but can also
transport Cd2+, Hg2+, Pb2+
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46. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Endocytosis
Receptor-mediated endocytosis
Iron-binding proteins - transferrin, ferritin,
lactoferrin can bind other metals
Out In Out In Out In
Fe3+
Apotransferrin
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47. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Take-home messages
There are multiple pathways of metal uptake into the
cell
No specific pathways of uptake exist for “toxic”
metals
Toxic metals use uptake routes, which have evolved
for uptake of essential metals such as iron, copper and
zinc
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48. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
General mechanisms of metal toxicity
Metals have multiple intracellular targets
Proteins
Substitution of essential metals in active centers of enzymes
Binding to thiol (SH) groups
Oxidative damage
Membranes
Membrane permeability
Oxidative stress
DNA
Interference with transcription, translation and repair
Oxidative damage
Interference with intracellular signaling pathways and Ca2+
metabolism
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49. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Oxidative damage
A hallmark of heavy metal toxicity
Free radical (ROS,
RNS)
Increase in free radical Decrease
production in antioxidants
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50. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Heavy metals increase ROS production
Direct effects
Haber-Weiss reactions
Meox+O2•-→ Mered+O2
Mered+H2O2→ Meox+ OH• +OH-
Net: H2O2+O2•-→ O2+OH• +OH-
Indirect (inhibition of the mitochondrial electron
transfer chain)
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51. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Oxidative damage to DNA
Single Cell Comet
Assay (single cell gel
electrophoresis)
SCGE
Detects DNA
fragmentation
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52. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Oxidative damage to DNA
TUNEL (TdT-mediated X-dUTP nick-end labeling) assay
Terminal uridine deoxynucleotidyl transferase
dUTP nick end labeling (TUNEL) is a common
Detects free –OH method for detecting DNA fragmentation that
groups created by results from apoptotic signaling cascades. The
assay relies on the presence of nicks in the
strand breakage DNA which can be identified by terminal
deoxynucleotidyl transferase, an enzyme that
will catalyze the addition of dUTPs that are
secondarily labeled with a marker. It may also
label cells undergoing necrosis or cells that
have suffered severe DNA damage.
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53. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
TUNEL-detected DNA damage in Cd-exposed
zebra fish embryos
Control
100 µ M Cd
Chan & Cheng (2002)
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54. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Cd-induced apoptosis in zebrafish
Control embryo
Cd-exposed embryos
Cd-exposed embryo
Chan & Cheng (2002)
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55. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Oxidative DNA damage may lead to
mutations
AT –GC transitions
Deamination of adenine or cytosine
G—C → G - - U (deamination) → G—C + A - -U (replication) →
G—C+ A—T (replication)
GC-TA transversions
8-hydroxyguanine
G—C → 8HOG—C → 8HOG - - A + G—C → T—A + G—C
(replication)
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56. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Oxidative damage to proteins and lipids
Lipids
Malondialdehyde (MDA)
Lipofuscin
Proteins
Carbonylation
Loss of iron from
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57. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Mutagenicity of cadmium
Jin et al., 2003 Nature Genetics
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58. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Inhibition of DNA repair
Isolated human cells exposed
to Cd in vitro
Jin et al., 2003 Nature Genetics
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59. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Toxic metal can affect function of zinc-
finger proteins
Hartwig (2001)
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60. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Take-home messages
Heavy metals affect a wide variety of intracellular
molecules and functions.
Two major mechanisms of heavy metal toxicity are:
Binding to –SH and nitro-groups of biomolecules
Cofactor substitution, conformational changes, etc.
Oxidative damage due to direct catalysis of ROS
production and/or to inhibition of ETC in mitochondria
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62. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Cadmium and renal effects
Cadmium accumulates especially in the kidneys leading to
dysfunction of the kidney with increased secretion of e.g.
proteins in urine (proteinuri) and other effects.
The proximal renal tubular dysfunction creates low phosphate
levels in the blood hypophosphatemia, causing muscle
weaknesses and coma. The dysfunction also causes Gout, a
form of arthritis due to the accumulation of sodium urate
crystals in the joints because of high blood levels of uric
acid (hyperuricemia). Another side effect are increased levels
of chloride in the blood (hyperchloremia). The kidneys can
also shrink up to 30%.
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63. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Markers of kidney
function:
tubular function:
Urinary excretion of
NAG
RBP
ß2-microglobulin
AA
Ca
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64. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Cadmium and liver toxicity
Intraperitoneal injection of CdCl2 in animals
cause:
Elevation of hepatic enzymes
Morphological changes in mitochondry and
endoplasmic reticulum of hepatocytes
Decrease of intracellular pH from 6.8 to 6.6
due to:
Cadmium interaction with Cl-/HCO3 channels
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65. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Cadmium and fractures
Chronic exposure to cadmium may
promote urinary calcium loss
Cadmium may interfere with the
metabolism of calcium, vit. D,
collagen
Severe cadmium poisoning is
associated with ostemalacia or
osteoporosis
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66. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Cadmium and fractures
In postmenopausal women, urinary
cadmium correlated negatively with
bone density.
The population-based risk for
fractures in districts near the smelters
was 35%.
Conclusion: cadmium may promote
skeletal demineralisation, which may
lead to increased bone fragility and
raised risk of fractures.
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67. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Cadmium and placenta
Cadmium induces placental necrosis at lower doses than renal
toxicity
Deposited in placenta, little into fetus
Blocks nutrient and blood flow: growth retardation, fetal death
Interferes with zinc
Responsible for the growth retardation caused by smoking
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68. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Cadmium and lung toxicity
edema and emphysema by killing lung
macrophages
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69. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Cadmium and cancer risk
Several occupational studies have reported an excess risk of
lung cancer in humans from exposure to inhaled cadmium.
Animal studies have reported cancer resulting from inhalation
exposure to several forms of cadmium, while animal ingestion
studies have not demonstrated cancer resulting from exposure
to cadmium compounds.
EPA(Environmental Protection Agency) considers cadmium to
be a probable human carcinogen (cancer-causing agent) and
has classified it as a Group B1 carcinogen
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70. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Itai itai
Itai itai
Itai itai
Itai itai Itai itai
Itai itai
Itai itai
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71. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
itai-itai disease
The itai-itai disease (Japanese: イタイイタイ病 , literally: ouch-ouch-
disease) From 1939 to 1954, some two hundred people near Fuchu, Japan
suffered from a condition termed 'Itai-itai‘
There are a number of symptoms associated with cadmium poisoning. The
two main organs affected are the bones and the kidneys. The bones get soft
(osteomalacia) and lose bone mass and become weaker (Osteoporosis).
This causes the pain in the joints and the back, and also increases the risk
of fractures. In extreme cases of cadmium poisoning the body weight alone
might cause a fracture.
The second affected organ is the kidney, which loses its function to remove
acids from the blood, a so called proximal renal tubular dysfunction. The
kidney damage due to cadmium poisoning is irreversible and does not heal
over time, and the victims of the itai-itai disease still have this disorder.
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72. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Is there a test for cadmium exposure?
There are several tests that indicate if someone has been
exposed to or been harmed by cadmium exposure. Urine or
blood samples can be tested to indicate current and past
exposure and may even be useful in determining if kidney
damage has occurred. Hair and fingernails or toenails are also
excellent biomarkers — biological indicators — for cadmium
exposure and can reveal past exposure to the metal
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73. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Cadmium health effects
Long-term exposure to cadmium at levels around 0.1
milligrams per cubic meter of air may cause kidney stones and
lung damage, and have been linked to lung cancer and high
blood pressure.
Short-term exposure at ten times that level may irritate the
lungs. Our everyday diet, however, only gives one-tenth the
amount that could possibly affect long-term health, but if you
eat large amounts of shellfish, liver and kidneys, or if you
smoke, you may consume more cadmium than you should.
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74. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
Cadmium health effects
The EPA has set a limit of 5 parts of cadmium per billion parts
of drinking water (5 ppb). EPA doesn't allow cadmium in
pesticides.
The Food and Drug Administration (FDA) limits the amount
of cadmium in food colors to 15 parts per million (15 ppm).
The Occupational Safety and Health Administration (OSHA)
limits workplace air to 100 micrograms cadmium per cubic
meter (100 µg/m³) as cadmium fumes and 200 µg cadmium/m³
as cadmium dust.
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de
to
xi
fi
Detoxification of metals
ca
ti
on
Biotransformation
Not possible for most metals
Biotransformation (methylation) of Hg makes it more toxic
Binding to intracellular ligands
Reduces the amount of biologically active form (free ion)
Deposition of insoluble metal granules
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de
Intracellular ligands for metal
to
xi
fi
ca
ti
on
binding
Histidine
Metallothioneins
Glutathione
CRP(cysteine rich proteins)
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de
to
xi
fi
Metallothioneins
ca
ti
on
Low molecular weight (60-68 aa,
6-7 kDa)
Cysteine-rich
In mammals – 20 Cys, bind
eqiuvalent of 7 bivalent metals
Cys positions are highly conserved
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de
to
xi
fi
ca
ti
on
Rat MT I
Blue crab MT II
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de
Cadmium bound to metallothionein
to
xi
fi
ca
ti
on
subunit
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de
to
Metallothionein is induced by exposure to
xi
fi
ca
ti
on
heavy metals
Nucella lapillus
Leung & Furness (1998)
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de
to
xi
fi
ca
Metallothionein protects from Cd toxicity
ti
on
Experimental
exposure to
toxic Cd levels
Survival:
Cd-
pretreated>control
Liver damage:
Control>Cd-
pretreated
Klaasen & Liu (1998)
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83. C a d m iu m M e t a b o l is m & P a t h o g e n e s is E f f e c t s
de
t ox
MT-knockout mice studies support protective role
if
ic
a ti
on
of MT against Cd toxicity
5 weeks 10 weeks
Liu et al., 1999
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de
t ox
MT-knockout mice studies support protective role
if
ic
a ti
on
of MT against Cd toxicity
Liu et al., 1999
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to
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fi
Cellular functions of metallothionein
ca
ti
on
Storehouse for Zn
Protection against Cd-toxicity
Free-radical scavenger
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de
to
xi
fi
Short peptide metal chelators
ca
ti
on
Glutathione
Phytochelatins
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to
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fi
Phytochelatines
ca
ti
on
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de
to
xi
fi
Cysteine-rich (intestinal) protein
ca
ti
on
Zn2+
Zn2+
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de
Deposition of insoluble granules
to
xi
fi
ca
ti
on
(invertebrates only)
Lysosome-derived granule in a snail Littorina littorea Marigomez et al. (2002)
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Take-home messages
Specialized proteins (metallothioneins) and polypeptides can
protect cells from heavy metal toxicity by binding metals
Cysteine has high affinity for metals and therefore is a key
amino acid in metal-binding proteins
Some invertebrates (mollusks, crustaceans, annelids) can
detoxify metals by deposition and excretion of insoluble
metal-containing granules
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discoverer=
crystal structure= nickel-cadmium
Fredrich color=bluish white
hexagonal batteries
Stromeyer
date of
discovery poisonous
=1817
boiling point= Cadmium paint pigments
765°C properties & application
atomic
number solders
=48
compounds
atomic
Are
mass= density=8.65g/cm³ oxidation state=2
toxic
112.41
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Respiratory System Kidney
Pneumonitis, Proteinuria, kidney stones,
destruction of glomerular & tubular
mucous membranes damage
Cancer Placenta
Excess risk of lung cancer Cadmium Deposition & necrosis
Classified in group B1 Block nutrient & blood flow
carcinogens
effects Growth retardation & fetal death
Reproductive System Skeletal System
Testicular necrosis, Loss of bone density and
estrogen-like effects, mineralisation,
affection of steroid-hormon Itai-Itai disease
synthesis
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Do we need cadmium for health?
Though trace amounts of many metals are
essential for the health of living things, there is
no scientific evidence showing a nutritional
role for cadmium.
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The First Cadmium Enzyme – Carbonic Anhydrase 2 from the
Marine Diatom Thalassiosira weissflogii
Cadmium is generally thought to be toxic and
was not thought to be used by nature in
anyway. X-ray absorption experiments on a
marine diatom showed that Cadmium is
not only of biological importance, but
plays an important role in the global
carbon cycle.
Lane, T.; Saito, M. A.; George, G. N.;
Pickering, I. J.; Prince, R. C.; Morel, F. F.
M. "Isolation and Preliminary
Characterization of a Cadmium Carbonic
Anhydrase from a Marine Diatom" Nature,
2005, 435, 42
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Cadmium (Latin cadmia , Greek καδμεία meaning "calamine", a Cadmium-bearing mixture of minerals, which was named after the Greek god, Κάδμος (Cadmus)) was discovered in Germany in 1817 by Friedrich Strohmeyer. Strohmeyer found the new element within an impurity in zinc carbonate (calamine) and for 100 years Germany remained the only important producer of the metal . The metal was named after the Latin word for calamine since the metal was found in this zinc compound. Strohmeyer noted that some impure samples of calamine changed color when heated but pure calamine did not. Even though cadmium and its compounds are highly toxic, the British Pharmaceutical Codex from 1907 states that cadmium iodide was used as a medicine to treat "enlarged joints, scrofulous glands, and chilblains". In 1927, the International Conference on Weights and Measures redefined the meter in terms of a red cadmium spectral line (1m = 1,553,164.13 wavelengths). This definition has since been changed (see krypton).
powder and pieces, Cd, Cd3As2, Cd3Sb2, CdCO3, CdCl2, CdF2,CdI2, CdMoO4, Cd2Nb2O7, Cd(NO3)2, CdO, CdP2, Cd3P2, CdSe, CdSeO3, Cd2SnO4, CdS, Cd2Ta2O7, CdTe, CdV2O6, CdO/ZrO2 from 99 % to 99.999 % lots delivered with analysis certificate
Smithsonite was named after James Smithson in 1832. James Smithson was an English scientist, often referred to as the best chemist and mineralogist of his year. He was an active member of many scientific organizations that benefited society and advanced scientific research. James published at least 27 papers with topics in chemistry, geology, and mineralogy. In 1802 James Smithson proved that zinc carbonates were true carbonate minerals, not zinc oxides. This discovery lead to the breakdown of calamine into two separate minerals hemimorphite and smithsonite. After James Smithson's death in 1829 the bulk of his estate was given to his nephew. Since his nephew died without any heirs the Smithson Estate was then given to the United States of America to found the Smithsonian Institution.
About three-quarters of cadmium is used in batteries (especially Ni-Cd batteries) and most of the remaining quarter is used mainly for pigments, coatings and plating, and as stabilizers for plastics. Other uses include: Other uses include: Used in some of the lowest melting alloys. Due to a low coefficient of friction and very good fatigue resistance, it is used in bearing alloys. 6% of cadmium finds use in electroplating . Many kinds of solder contain this metal. As a barrier to control nuclear fission . Compounds containing cadmium are used in black and white television phosphors and also in the blue and green phosphors for color television picture tubes. Cadmium forms various salts , with cadmium sulfide being the most common. This sulfide is used as a yellow pigment. Cadmium selenide can be used as red pigment, commonly called cadmium red . To painters who work with the pigment, cadmium yellows, oranges and reds are the most potent colours to use. In fact, during production these colours are significantly toned down before they are ground with oils and binders, or blended into watercolours, gouaches, acrylics, and other paint and pigment formulations. These pigments are toxic and it is recommended to use a barrier cream on your hands to prevent absorption through the skin when working with them. There is no such thing as cadmium blue, green or violet. Used in some semiconductors such as cadmium sulfide, cadmium selenide, and cadmium telluride , which can be used for light detection or solar cells . HgCdTe is sensitive to infrared. Some cadmium compounds are employed in PVC as stabilizers. Used to block voltage-dependent calcium channels from fluxing calcium ions in molecular biology.
Density=8.65g/cm³
The Comet Assay , also called single cell gel electrophoresis (SCGE), is a sensitive and rapid technique for quantifying and analyzing DNA damage in individual cells. As such, this is one of the techniques used in the area of cancer research for the evaluation of genotoxicity and effectiveness of chemoprevention. Swedish researchers Östling & Johansson developed this technique in 1984 [1]. Singh, et al., later modified this technique, in 1988, as the Alkaline Comet Assay [2]. The resulting image that is obtained resembles a "comet" with a distinct head and tail. The head is composed of intact DNA, while the tail consists of damaged (single-strand or double-strand breaks) or broken pieces of DNA. While most of the applications of the Comet Assay have been to study animal eukaryotes, there have been reports of successful application in the study of plant cells. Individual cells are embedded in a thin agarose gel on a microscope slide. All cellular proteins are then removed from the cells by lysing. The DNA is allowed to unwind under alkaline/neutral conditions. Following the unwinding, the DNA undergoes electrophoresis, allowing the broken DNA fragments or damaged DNA to migrate away from the nucleus. After staining with a DNA-specific fluorescent dye such as ethidium bromide or propidium iodide, the gel is read for amount of fluorescence in head and tail and length of tail. The extent of DNA liberated from the head of the comet is directly proportional to the amount of DNA damage. The Comet Assay can be used to detect DNA damage caused by double strand breaks, single strand breaks, alkali labile sites, oxidative base damage, and DNA cross-linking with DNA or protein. The Comet Assay is also used to monitor DNA repair by living cells [3].
EPA: Environmental Protection Agency
Biotransformation is the chemical modification (or modifications) made by an organism. If this modification ends in mineral compounds like CO 2 , NH 3 + or H 2 O, the biotransformation is called mineralisation