Metals and Metalloids

Question 1

What is the primary concern with metals from a toxicological standpoint?

Answer 1

They do not degrade

Question 2

What in particular drives the release of toxic metals in today’s society and why?

Answer 2

Industrial sites like mines, because they release a transformed form of the metal that is more biologically active

Question 3

What are class A metals?

Answer 3

Metals that bind Oxygen, nitrogen and sulfur in that order

Question 4

What functional groups do Class A metals bind to?

Answer 4

alcohols, carbonyls, phosphate, phosphodiester or carboxylate

Question 5

What are some examples of Class A metals?

Answer 5

Potassium, magnesium and calcium

Question 6

What are Class B metals?

Answer 6

metals that bind sulfur, nitrogen and oxygen in that order

Question 7

What functional groups do Class B metals bind?

Answer 7

sulfhydryl, disulfide, thioether, and amino

Question 8

What are examples of class B metals?

Answer 8

Cadmium, copper, mercury and silver

Question 9

What are the abiotic factors affecting bioavailability in aquatic ecosystems?

Answer 9

hardness, pH, concentration of inorganic and organic matter

Question 10

How does hardness of the water affect bioavailability of metals?

Answer 10

The hardness cations can increase the uptake of toxic metals

Question 11

How does the pH of water affect bioavailability of metals?

Answer 11

If the water is alkaline, the water is automatically harder

Question 12

What creates alkaline water?

Answer 12

carbonate, bicarbonate and hydroxide

Question 13

How does the presence of inorganic/organic compounds affect bioavailability of metals?

Answer 13

Biotic ligands have a negative charge meaning that they readily bind the positive metal cations and can cause complexation

Question 14

What type of water would be more susceptible to metal toxicity?

Answer 14

Freshwater, saltwater has higher alkalinity

Question 15

What are the abiotic factors affecting bioavailability in soils?

Answer 15

alkalinity, hardness and concentration of inorganics to organics, due to pore water present

Question 16

What metals can be easily passed through trophic levels

Answer 16

mercury and selenium

Question 17

What are the enzymes that deal with metals?

Answer 17

Metallothioneins (MT) and glutathione chelating (GSH)

Question 18

How do these enzymes work?

Answer 18

They have high levels of cysteine to easily bind metals

Question 19

What is present in invertebrates to deal with metal toxicity and give an example of an organism that does it?

Answer 19

metal reach granules that store away metals so they can’t cause toxicity, woodlice

Question 20

What are metals MOA?

Answer 20

enzyme/protein attenuation or generate ROS

Question 21

How do metals disrupt enzymes and proteins?

Answer 21

bind active site of enzyme or displace other enzymatic cofactors

Question 22

What is an example of a cofactor and what metal replaces it?

Answer 22

Zinc and it can be replaced by lead or cadmium meaning they can no longer bind

Question 23

What metals cause the most production of ROS?

Answer 23

Fe, Cu and Cr

Question 24

What are the ROS scavenging enzymes?

Answer 24

SOD, GPX and CAT

Question 25

Where is cadmium produced?

Answer 25

rocks, soils, batteries, electroplating, galvanizing and cigarettes

Question 26

What is cadmiums primary target in the body and how long can it last?

Answer 26

kidneys, 10-33yrs

Question 27

What is cadmium's MOA?

Answer 27

Ca2+ analog, and it binds to SH causing enzyme dysfunction-decrease in metallothioneins and ROS scavenging proteins

Question 28

What is Itah-itah disease

Answer 28

Cadmium poisoning, found in Japan after mine leeched cadmium into river causing rice to have high levels of cadmium, slightest pressure can cause a broken bone

Question 29

Where in Canada was there a concern for cadmium leeching?

Answer 29

gold mine in yellowknife

Question 30

What is the number one influence affecting cadmium bioavailability?

Answer 30

hardness-increased hardness = decreased toxicity

Question 31

What is selenium?

Answer 31

an essential metalloid

Question 32

What are the two forms of selenium?

Answer 32

organic-selenomethionine and selenocysteine inorganic-selenide, selenite, and selenate

Question 33

Where does selenium come from?

Answer 33

coal mining, oil refining, uranium, copper, lead and zinc ores and soil

Question 34

Which of the two forms of selenium are more toxic?

Answer 34

organic

Question 35

How is selenium often passed through the food chain and what is the difference is biomagnification between 1st and 3rd/4th trophic levels?

Answer 35

inorganic selenium is bioactivated through microorganisms and easily passed through food chain, 100 fold difference between trophic levels

Question 36

What is seleniums MOA?

Answer 36

replaces sulfur in amino acids and thus impairs protein synthesis, also catalyzes ROS damage

Question 37

Where is selenium accumulated in the body?

Answer 37

liver and gonads

Question 38

What animals are most susceptible to cadmium poisoning and why?

Answer 38

birds and fish that lay eggs because it can leech into the yolk

Question 39

What other problems does cadmium cause?

Answer 39

developmental malformations (teratogenicity), reproductive failure, neurotoxicity amd damage to liver, kidney and heart