45 - Metal Toxicity Flashcards
Mercury
TOXICITY
- *80% INHALED**
- not well absorbed by GUT*
- can be absorbed* THROUGH THE SKIN
Lethargy / confusion / visual distrubances
can be misdiagnosed as PARKINGSONS / ALZ
Cadmium
TOXICITY
Binds to SULFHYDRYL GROUPS
competes with calcium
Affects Lungs + Kidneys
also Skeletal system
LIPID Peroxidation
Cadmium and MT
Cadmium INDUCES synthesis of METALLOTHIONEIN
transports metals –> LIVER
shows a decreased FXN/Activity of CYP450
Also damages the KIDNEY
Mercury
SOURCES
TUNA / FISH / CONTAMINATED FOOD
used to be found in some
VACCINES
Dental fillings
Electrical Switches / Bulbs / Lamps
Batteries / THERMOMETERS
LEAD’s CHRONIC & LONG-TERM
Toxicity Pathophysiology
Affinity for SH GROUPS & displaces ZINC dependednt enzymes
HEME synthesis
Steroid Metabilism / Membrane integrety
interfere with VIT D synthesis
General Properties of
TOXIC METALS
electron acceptors
Selective affinity to -SH GROUPS
prefer to react with Sulhydryl Groups = RSH
- *Metabolic Poisons**
- *proteins / enzymes**
- *COMPETE w/ other metals**
- *displace essential metal cofactors**
Metal Toxicity
Mechanism of ACTION
Most common route of exposure =
ORAL > inhalation of fumes (mercury more toxic in vapor)
Ability of metals to
bind to 1+ ligands of ENZYME SYSTEMS
–> INACTIVATES enzyme system
all metals have similar symptoms of toxicity
Toxic Heavy Metals
Lead = Pb
most significant of the heavy metals
Mercury = Hg
Cadmium = Cd
Arsenic = As
actually a metalloid, intermediate between metal/non-metal
Cadmium Sources
Batteries // Yellow Paint // TV screens
Coal Burning // Smelters
CIGARETTE SMOKE
Fertilizers + Pesticides
kids eating DIRT
MoA of LEAD TOXICITY
DISRUPTS HEME SYNTHESIS
inhibits porphobilinogen synthase –> elevated ALA
SIMILAR TO CALCIUM
competes –> stored in bone
Interacts with Nucleic acids –> decreases protein synthesis
Highly reactive to -SH Groups –> Mercaptide
Can inactivate enzymes / proteins:
Adenylcyclase + Aminotransferase
Lead Storage
Primary site is the BONE
is the reason why LEAD stays in the body for SO LONG
contributes to 40-70% of lead released into the blood
–> CHRONIC / LONG-TERM Toxicity
Mercury Toxicity
Treatment
Depends on Absorption / type of mercury
Usually without SEQUELA
O2 + Chelation
Lead (Pb)
Toxicity
Toxic metal that causes the MOST HUMAN HEALTH PROBLEMS
no “SAFE” level of exposure, NOT NEEDED in the body
OXIDATIVE STRESS
Irreversible health effects:
CNS / Hematopoietic / Renal / Hepatic
–> BBB/PLACENTA –> LOWER IQ LEVELS IN CHILDREN
Neurologic + REPRODUCTIVE system
can be transferred POST-NATALLY (breast milk)
3 Forms of Mercury
All are toxic, difference is just how it is absorbed
1.organic
readily passes through the PLACENTA –> abortion/retardation
2.mecuric salts -
is highly toxic and corrosive
3.elemental
as a vapor can penetrate the CNS
Medicinal Treatment for
HEAVY METAL POISONING
CHELATION THERAPY
chelating agents:
EDTA / BAL
Nutritional Supplementation
Iron / Calcium / Phosphorous
to displace the toxic metals
