TOX 6 - Mercury

Question 1

Source

Answer 1

Medical
Industrial
Domestic
Dietary: inorganic mercury from industrial waste
 transformed to methylmercury by soil, marine organisms
 bio-amplified in tissues of predatory fish (e.g. tuna)
Household items (e.g. fluorescent bulbs, batteries, paint)
Fungicides, pesticides
Mining
Dental amalgam

Question 2

Elemental/metallic mercury exposure

Answer 2

Absorption - respiratory tract (liquid)
Distribution - CNS and kidneys
Elimination - urine

Question 3

Inorganic/organic exposure

Answer 3

Absorption - GI
Distribution - both kidney, and organic may also target brain and blood
Elimination - urine

Question 4

Pharmocodynamics

Answer 4

Readily binds to sulfhydryl groups -> enzyme inhibition and protein precipitation

Lipid soluble; easily crosses cellular membranes
binding to functional groups (sulfhydryl, carboxyl, phosphoryl)
High affinity for sulfhydryl groups in red blood cells
–> distributed throughout body
Concentrates in kidneys
oxidative damage on pulmonary and GI

Question 5

Acute intoxication cause

Answer 5

Mainly inorganic

Question 6

Acute intoxication overall effects

Answer 6

Precipitation of proteins damages mucosa and induces vomiting, followed by mucosal destruction and critical organ damage
*Neurotoxicity, interruption of cellular processes, teratogenesis.

• Cough,
• dyspnea,
• circulatory collapse,
• vomiting,
• bloody diarrhea

Question 7

Acute intoxication treatment

Answer 7

Identification and removal of exposure

Chelating treatment with dimercaprol , DMSA, DMPS,

Supportive therapy

Question 8

Chronic intoxication- inhalation

Answer 8

Less heavy on kidneys and GI, and is affecting CNS more

Treatment is mainly symptomatic

Chronic inhalation exposure (classic triad)

1. Tremor,
2. Neuropsychiatric problems (memory loss, fatigue, mental instability)
3. Gingivostomatitis

Question 9

most common organic mercury

Answer 9

methylmercury (Minamata disease)

Question 10

Mechanism of mercury

Answer 10

• Crosses blood-brain barrier–>neurotoxic effects
• Impairs synthesis of proteins and nucleic acids
–> disrupts neurotransmitter synthesis and uptake
• Crosses placenta-> concentrates in fetus(teratogenic effects)

Question 11

Chronic ingestion:

Answer 11

- Nervous system: tremor, headache, dysarthria, paresthesia, irritability, psychosis

-Cardiovascular: hypo/hypertension

- Hematologic: cytopenia

- Ocular: conjunctivitis; corneal opacities, ulcers