toxic metal review

Question 1

how to measure exposure

Answer 1

blood (recent, acute)
urine (recent, acute)
hair (not reliable)

Question 2

exposure in children

Answer 2

ingestion is major pathway.
Higher GI absorption of metals than adults, particularly lead.
rapid cell division = oppurtunities for genotoxic effect

Question 3

metal-binding proteins

Answer 3

metallothioneins: for metal detox specifically.
Transferrin: ferric ion
Ferritin: iron storage in liver, spleen and bone.
Ceruloplasmin: converts ferrous to ferric iron.
heme: contain iron

Question 4

Chelation therapy is?

Answer 4

binding metal ion to ligand, forming ring-structure (trapping metal in the ring).
Metals react with OH, COOH, SH, NH2, NH and N

Question 5

chelating agents are?

Answer 5

water-soluble, resistant to biotransformation, able to reach metal storage/target, can form non-toxic complex with metals, can be excreted and low affinity for essential metals

BAL (british anti-lewisite): arsenic antagonist, also effective against other metals

Question 6

Arsenic exposure route

Answer 6

pesticide, herbicide and from smelting industries

Question 7

arsenic MOA

Answer 7

inhibits succinic dehydrogenase and uncouples oxidative phosphorylation, prevent ATP generation, increase H2O2

Question 8

arsenic sx

Answer 8

fever, anorexia, heptaomegaly, anemia, arrhythmia, PNS/CNS neurotoxic, demyelination, liver injury.
Also decrease fertility and malformation of fetus. Carcinogenic.

Question 9

Cadmium route of exposure

Answer 9

biomaginification from plants and shellfish

Question 10

cadmium sx

Answer 10

acute: nausea, abd pain, PE
chronic: emphysema, renal disease, skeletal problems
nephrotoxicity: binds to sulfhydryl groups in tubular and glomeruli cells. Thionein for detox

Question 11

Lead exposure

Answer 11

food, water, paint, industrial emissions

Question 12

Lead sx

Answer 12

neurologic, neurobehavioral and developmental effects on children.
vomiting, lethargy, ataxia, encephalopathy, coma, death.
Recovery accompanied by epilepsy, retard and blindness

Question 13

Lead MOA

Answer 13

modification of neuronal circuitry, axonal degeneration and demyelination, heme synthesis disruption

Question 14

Mercury exposure and sx

Answer 14

natural degassing of earth’s crust and biomaginification in fish.
Sx: vapor voxicity (bronchitis, CNS toxic and gingivitis) and methyl mercury (numbness, ataxia, weakness, coma, death)

Question 15

Nickel exposure and sx

Answer 15

inhlation, ingestion or dermal contact.

Sx: carcinogen (resp) and allergic dermatitis

Question 16

Essential metals are…

Answer 16

Copper, iron and zinc

Question 17

Copper exposure and sx

Answer 17

water and food.
Wilson’s disease: accumulation in liver, braind and kidney if can’t excrete via bile.
Sx: nausea, hepatic necrosis, death

Question 18

Iron exposure, MOA and sx

Answer 18

overdose of iron pills.
increased lipid peroxidation (membrane damage).
vomiting, liver damage, coagulation defect, renal failure, etc.

Question 19

Zn exposure and toxicity

Answer 19

seafood, diary products and legumes.

GI distress