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Heavy metal poisoning
toxic accumulation of heavy metals in the soft tissues of the body
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Methods for heavy metals to enter the body
- food
- water
- air
- absorption through the skin
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Heavy metals compete with and displace ___ in the body
- essential minerals
- zinc
- copper
- magnesium
- calcium
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Treatment of heavy metal poisoning
- minimize long-term damage to the patient's nervous system and digestive tract
- pt should be takent to an emergency room
- treatment for most is chelation therapy
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Chelating agents specific to the metal involved in poisoning can be given
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Complexation and chelation therapies
- BAL
- DMPS
- DMSA
- CaNa2
- Deferoximine
- Penicillamine and N-Acetylcysteine
- Hemodialysis with chelation
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A provoking agent in testing for the presence of heavy metals and as a treating agent for heavy metal toxicity
DMPS
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Blood levels of heavy metals a few hours after exposure
- blood levels low
- tissue levels high
- must use provoking agent
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Major toxic metals with multiple effects
- arsenic
- beryllium
- cadmium
- lead
- mercury
- nickel
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Arsenic poising is shown by
lesions on hands
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Beryllium poisoning results in
pancreatic cancer
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No known biological function in animals and is highly toxic
arsenic
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sources of arsenic
- pesticides/herbicides/fungicides
- ceramic/enamels
- paints/wood preservatives
- 6 mcg/pack of cigarettes
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Arsenic compounds are _____ to body systems
directly toxic
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Main clinical signs of arsenic poisoning
- hemorrhagic gastroenteritis
- fluid loss
- n/v
- abdominal pain
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Carcinogenicity of arsenic
- proven carcinogen of lung and skin
- suspected bladder or kidney carcinogen
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Treatment of arsenic poisoning
- dimercaprol
- penicillamine (less effective)
- DMPS
- DMPS + Dimercaprol (very effective)
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Aldrich-Mees lines
white lines in the nail beds resulting from Arsenic exposure
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Chronic exposure to cadmium
accumulation in the body, particularly in the kidneys and liver
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Cadmium is found in
- alloys/batteries
- pigments
- metal coatings
- occupational exposure from welding and smelting lead, zinc and copper
- cigarette and vehicle fumes
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Acute intake of cadmium causes
- testicular damage
- severe gastrointestinal irritation (N/V)
- abdominal cramps (diarrhea)
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Lethal dose of cadmium ingestion
350-8900 mg
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Prolonged cadmium exposure results in
- disorders of calcium metabolism causing osteomalacia
- lung and prostate cancer
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t 1/2 of cadmium
- 15-30 years
- body burden increases with age
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Treatment for cadmium exposure
- no effective treatment
- supportive therapy for symptoms
- chelating agents?
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Lead exposure results in
- accumulation in the body
- intelligence loss and behavioral difficulties
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Sources of lead
- tetraethyl lead in petrol and plumbing
- lead in paint, batteries, insecticides and cigarette smoke
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Lead absorption
- lead or inorganic lead absorbed by ingestion or inhalation
- organic lead (tetraethyl lead) may be absorbed through skin
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Gastrointestinal absorption of lead
- varies with age
- children absorb around 50%
- adults absorb 10-20%
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Lead t1/2
- blood = 25 days
- tissue = 40 days
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Lead has an affinity in the body for
- cell membranes & mitochondria
- interferes with oxidative phosphorylation
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symptoms of lead toxicity
- thirst and metalic taste
- n/v/d
- colic
- muscle pain/fatigue
- convulsion
- loss of consciousness
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Death from lead toxicity may result from
cerebral edema or renal failure
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Treatment of lead poisoning
- DMSA is more effective than penicillamine
- CaNa2 EDTA IV for more acutely ill patients
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Mercury produces illnesses such as
- multiple sclerosis
- alzheimer's disease
- parkinson's disease
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Sources of mercury poisoning
- liquid contact for electric switches
- scientific instruments such as thermometers, barometers, direct current meters, hydrometers
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Mercury exerts its toxicity by bidning to
sulphydryl groups in the body
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acute inhalation of mercury vapro produces symptoms similar to metal fume fever such as:
- cough
- dyspnea
- tight/burning chest pain
- pyrexia
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Severe cases of mercury poisoning may result in
- respiratory distress
- pulmonary edema
- pneumonia
- fibrosis
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Treatment for mercury poisoning
- chelating agents >> Dimercaprol
- DMPS is more effective than dimercaprol and should be used with penicillamine later
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Recovery from mercury poisoning
- can take months or years
- often incomplete even with chelation therapy
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Nickel toxicity
- medium toxicity to humans
- dermatitis/skin allergy reactions
- lung and nasal carcinogen
- adverse effects on heart, blood and kidneys
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Mechanism of nickel toxicity
nickel can preleace metals in metallo-enzymes and cause disruption of metabolic pathways
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Essential metals with potential for toxicity
- cobalt
- trivalent chromium
- copper
- iron
- magnesium
- manganese
- selenium
- molybdenum
- zinc
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low levels of cobalt
part of vitamin b12
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high levels of cobalt
harm the lungs and heart
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chromium absence in the body may result in
- heart conditions
- disruptions of metabolism
- diabetes
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Chromium VI
- danger to human health
- exposure in steel and textile industry
- also in cigarettes
- in leather products may cause allergic reactions
- also in fertilizers
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Metals related to medical therapy
- aluminum
- bismuth
- gallium
- gold
- lithium
- platinum
- barium
- vanadium
- uranium
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aluminum found in ___ and can cause ___
- antacids
- alzheimer's disease
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Bismuth found in
antacid preparations
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Gallium used as
antitumor agent
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Gold used for
rheumatoid arthritis
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lithium use
antidepressive
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platinum
anticancer agent
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barium
aid to x-ray diagnostics
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vanadium
essential trace element
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uranium
- military nuclear uses
- destroys cells easily
- found in missel casings
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