Mercury

Question 1

why is the standard conc of mercury so low in water?

Answer 1

because it biomagnifies

Question 2

what are the forms of Mercury, and which is most toxic?

Answer 2

Alkyl (methyl, ethyl), most toxic; aryl, inorganic

Question 3

how is mercury converted to methylmercury?

Answer 3

via anaerobic bacteria mechs–> convert mercuric ions to methylmercury with the use of vit B12 and tetrahydrofolate

Question 4

how are the different forms of mercury absorbed?

Answer 4

1. elemental Hg– mostly high resp absorption (50-100)
2. inorganic Hg – low resp, GIT 20%, low skin and v low placenta
3. alkyl mercury– more lip sol, so high GIT (90%), skin low, v high placenta

Question 5

Hg distribution

Answer 5

kidney>liver>brain

with methylmercury, very high dist in placenta/fetus

Question 6

Excretion of Hg

Answer 6

feces, urine, bile; half life = 70-90

Question 7

Clinical toxicity of Hg

Answer 7

metal mercury–resp syndrome and pneumonitis

inorganic mercury– corrosive, vomiting, diarrhea (GIT)

Question 8

CNS manifestations of inorganic Hg

Answer 8

asthenic vegetative syndrome–psych changes, memory loss, muscle weakness (from nerve damage)
mercurial tremor
mercurial erethism–behavioural changes

Question 9

other manifestations of Hg

Answer 9

Kidney, and hypersensitivity– immune system targets organs; rashes on skip

Question 10

clinical manifestations of methylHg

Answer 10

• sensory disturbances–tingling;
• ataxia–>damage to neurons
• loss of visual fields-
• hearing loss
• salivation–>controlled by NS, disturbed
• GIT– NO GIT signs
• kidney– all kinds of problems
• highly teratogenic

Question 11

other effects of mercury

Answer 11

immunosuppression
cocarcinogen
genetic effects – disrupts cell division, damages chromosomes, radiomimetic effects;
disrupts meiosis–non-disjunction, inversions, point mutations

Question 12

treatment for Hg

Answer 12

BAL, proteins with SH; possibly chelators