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CLINICAL TOXICOLOGY > HEAVY METAL POISONING > Flashcards

HEAVY METAL POISONING Flashcards

1
Q

Specific gravity of heavy metals in their standard state

A

Above 5g/cm3

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2
Q

Which heavy metals are released into water by industrial and domestic waste

A

Pb
Hg
As
Cd

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3
Q

Long term use of fertilizers lead to accumulation of which heavy metal

A

Cd

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4
Q

Sewage or sludge application releases which heavy metals

A

Hg
Cd

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5
Q

Dust from smelters, industrial waste and bad agricultural watering practices contaminate agricultural lands with which heavy metals

A

Hg
Cd
As
Pb

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6
Q

How are plants contaminated by heavy metals

A

Fertilizers/Pesticides/Insecticides

Plants growing in soil contaminated area

Irrigation of crops with contaminated water

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7
Q

Plants method for detoxification of heavy metals is is mainly based on ————-//

A

Chelation subcellular compartmentalization

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8
Q

Five processes of phytoremediation

A

Rhizodegradation
Rhizofiltration
Phytoextraction/ Phytoaccumulation
Phytovolatilization
Phytostabilization

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9
Q

Examples of toxic metals that have no know beneficial effects in organisms

A

Plutonium
Lead

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10
Q

Most hazardous heavy metals that humans are exposed to

A

As, Pb, Hg, Cd, Fe and Al

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11
Q

Factors that affect toxicity of heavy metals

A

Dose absorbed
Exposure was acute or chronic
Age of the person

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12
Q

Why are young children more susceptible to effects of lead exposure

A

Their brains are more plastic and even brief exposures can influence developmental processes

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13
Q

Major sources of arsenic and mercury indoors

A

Pesticides and Fungicides

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14
Q

Methods for measuring trace metals

A

Atomic absorption spectrophotometry -destructive , sample should be in solution

X-ray fluorescence - nondestructive , sample can be in any state

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15
Q

Easiest screening process for heavy metal
Poisoning

A

Hair analysis

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16
Q

Steps involved in treating heavy metal poisoning

A

Decontamination
Resuscitation
Chelation

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17
Q

Toxicity of EDTA

A

Hypocalcémic tetany
Hydropic vacuolization of the proximal tubule
Loss of the brush border
Degeneration of proximal tubules

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18
Q

Why is mercury unavailable to EDTA

A

Tightly bound by sulfhydryl groups or sequestered in body compartments that are not penetrated by EDTA

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19
Q

Does EDTA penetrate cells

A

It does not significantly penetrate cells hence has a volume of distribution approximating ECF space

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20
Q

Disadvantage of DTPA

A

Depletes Zn
Teratogenic lime EDTA due to its Zn and Mn depletion effect
Limited access to intracellular sites

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21
Q

Which solvent is used for Dimercaprol

A

Peanut oil due to its instability in aqueous solutions

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22
Q

Why is Dimercaprol nephrotoxic

A

Sulfur-metal bond is unstable labile in acidic tubular urine increasing delivery of metal to renal tissue and increase toxicity

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23
Q

Another name for Dimercaprol

A

British Antilewisite BAL

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24
Q

Chelators used in Treatment of lead encephalopathy in due to lead poisoning

A

Dimercaprol + CaNa2EDTA

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25
Q

Route of administration of dimercaprol

A

Deep Intramuscular injection as 100mg/ml solution in peanut oil

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26
Q

Toxicity of dimercaprol

A

Hypertension
Tachycardia

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27
Q

Difference between succimer and dimercaprol

A

Succimer has two carboxylic groups hence has less lipid solubility

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28
Q

Desirable features of succimer

A

Does not significantly mobilise essential such as Zn, Cu and Fe

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29
Q

Difference between toxicity of dimercaprol and succimer

A

Succimer is less toxic due to its lower lipid solubility which minimizes cellular penetration

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30
Q

Why is n acetyloenicillamine more effective than penicillamine for mercury toxicity

A

More resistant to metabolism

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31
Q

Toxicity of penicillamine

A

Cutaneous lesions
Urticaria
Macular or papular reactions
Pemphigoid lesions
Lupus
Dermatomyositis
Adverse effects on collagen

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32
Q

Which chelator has prooxidant effects

A

DTPA

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33
Q

Aerobic bacteria involved in bioremediation

A

Mycobacterium
Sphingomonas
Alcaligenes
Rhodococcus
Pseudomonas

34
Q

Examples of hyperaccumulator plant species

A

Avena spp
Brassica spp

35
Q

Commonest source of acute metal poisoning

A

Arsenic

36
Q

Least toxic form of arsenic

A

Elemental arsenic

37
Q

Most popular homicidal poison

A

Arsenic

38
Q

Why is arsenate less toxic than arsénite

A

It is has less water solubility

39
Q

Most toxic form of arsenic

A

Arsine gas ( 25-30ppm) can be lethal in 30mins

40
Q

Toxic dose of arsenic trioxide

A

200-300mg

41
Q

Routes of absorption of arsenic

A

All routes

42
Q

Effect of arsenic on bone

A

Replaces phosphorus in bone

43
Q

Does arsenic cross the BBB

A

No

44
Q

Teratogenic effects of arsenic

A

Intrauterine death of the fœtus
Or
Respiratory distress in less severe cases

45
Q

How does arsenic cause respiratory distress in the fœtus

A

Pulmonary hemorrhage and hyaline membrane formation

46
Q

Three clinical forms of arsenic poisoning

A

Acute fulminating type
Subacute type( gastroenteritis type)
Chronic type

47
Q

Effects of acute arsenic toxicity

A

Capillary dilatation
Myocardial failure
Shock
Death

48
Q

Mechanism of acute arsenic toxicity

A

Acts on sulfhydryl groups of enzymes and capillaries and inhibit cellular metabolism

49
Q

Symptoms of sub acute type arsenic poisoning

A

Resembles cause of food poisoning or cholera

50
Q

Five manifestations of chronic type arsenic toxicity

A

Gastrointestinal
Catarrhal
Raindrop pigmentation
Mees lines
Arsenic neuritis

51
Q

Gastrointestinal symptoms of arsenic toxicity

A

Gradual weight loss
Malnutrition
Fatigue
Loss of appetite

52
Q

Catarrhal symptoms of chronic arsenic toxicity

A

Running nose
Headache
Conjunctivitis
Bronchial catarrh

53
Q

Raindrop pigmentation

A

Milk and roses pigmentation followed by brown patchy pigmentation of the skin

54
Q

Mees lines

A

Whitish lines across the nails of the fingers and toes

55
Q

Symptoms of arsenic neuritis

A

Polyneuritis
Optic neuritis
Paraesthesias
Atrophy of extensors regulating in wrist and food drop

56
Q

Diagnosis of chronic arsenic toxicity

A

Urinary As level > 100mg/24 hours

57
Q

Which metal poisoning causes garlic steel to breath and tissue fluids

A

Arsenic

58
Q

Manifestations of arsine gas exposure

A

Acute hemolytic anemia and striking chills

59
Q

Most common neurological effect of chronic arsenic intoxication

A

Sensory predominant peripheral neuropathy in a stocking glove pattern

60
Q

Types of skin reactions caused by arsenic dust

A

Toxic
Eczematous
Combined toxic and eczematous
Follicular lesions

61
Q

Describe the classical dermatitis caused by chronic arsenic toxicity

A

Hyperkeratosis with a classical dew drops on a dusty road appearance

62
Q

Diagnosis of arsenic toxicity

A

Urine level
Blood level
Hair level
Radiography

63
Q

Levels of arsenic in urine which indicate toxicity

A

24hr excretion more than 100mcg/L

64
Q

Metabolites of arsenic

A

Methylarsonic acid
Dimerhyarsenic acid

65
Q

Chelation therapy for arsenic

A

Dimercaprol
Penicillamine
DMPS and DMSA are superior

66
Q

Which urine urine level of arsenic in an asymptomatic patient prompts chelation

A

200mcg/L

67
Q

Most commonest metal involved in chronic poisoning

A

Lead

68
Q

Forms of lead and uses

A

Lead acetate - therapeutics
Lead carbonate(white lead)- paints
Lead oxide (litharge)- glazing of pottery and enamel ware
Tetraethy lead - mixed with petrol as an antiknock
Lead tetraoxide - vermillion
Lead sulfide- collyrium (surma)

69
Q

Routes of absorption of lead

A

All portals of entry

70
Q

Which form of lead can be absorbed directly through the skin

A

Tetraethyl lead

71
Q

Route of Occupational exposure to lead

A

Inhalation

72
Q

Routes of excretion lead

A

Urine and Bile

73
Q

Mode of action lead

A

Inhibits sulfhydryl enzymes
Decreases heme synthesis
Increases hemolysis
Edema in CNS
Affects CVS

74
Q

Enzymes Involved in heme synthesis that are affected by lead

A

Aminolaevulinic acid synthetase

Aminolaevulinic acid dehydrase

Ferrochelatase

Corporphyrinogen oxidase

75
Q

Effects of lead on CVS

A

Hypertension and Myocarditis

76
Q

In what forms is lead stored in bones

A

As phosphate and carbonate

77
Q

Effect of lead on kidney

A

Nephritis

78
Q

What is plumbism

A

Lead toxicity

79
Q

What is the burton line or gingival lead line

A

Dark blue line along the gums that signify lead poisoning

80
Q

Management of cerebral edema in lead poisoning

A

Mannitol Or Glycerol
Dexamethasone

81
Q

Management of seizures in lead encephalopathy

A

Diazepam

CLINICAL TOXICOLOGY (14 decks)

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