Chapter 3

Question 1

Define: Poison

Answer 1

Especially toxic substance; connotations of causing death; overarching term: toxicant

Question 2

Toxic Endpoints (Experimental toxicology point of view)

Answer 2

Adverse effects

Question 3

Toxic Endpoint (Epidemiologists who study adverse effects in human populations point of view)

Answer 3

Human outcomes

Question 4

What does dose of toxicants depend on?

Answer 4

Concentration of toxicants in food and amount of food consumed

Question 5

Hormesis

Answer 5

The beneficial response of a toxic substance at low doses

Question 6

What does a dose-response curve generally look like for potent toxicants? What does it indicate?

Answer 6

The curve is usually farther to the left. This indicates a lesser does is needed to cause same level of harm.

Question 7

What does a does-response curve generally look like for a highly specific toxicant? What does it indicate?

Answer 7

The curve is usually steeper. This indicates that very little additional dose is needed to increase level of response.

Question 8

Dose-response curves vary depending on four factors. What are they?

Answer 8

1. Type of measured effects and responses 2. Sensitivity or susceptibility of animal to toxicant 3. Toxicant’s potency and specificity 4. Rates of toxicant metabolism and elimination

Question 9

What does LD50 indicate?

Answer 9

The dose at which an estimated 50% of tested animals experienced fatal effects

Question 10

What is the primary value of LD50?

Answer 10

To compare relative lethality of several toxicants

Question 11

What is ED50? What does it indicate?

Answer 11

Effective Dose 50 indicates the dose at which 50% of tested animals experience predetermined effects (not fatal)

Question 12

ADME

Answer 12

Absorption, Distribution, Metabolism, Elimination. Other factors that determine target organ and types of degree of adverse effects.

Question 13

Example of latent effect of toxic exposure

Answer 13

Cancer; May take years to be clinically recognizable

Question 14

Name 2 specific bacterial toxins

Answer 14

1. Staphylococcal Enterotoxins 2. Botulinum Toxins

Question 15

Name 2 sources of mycotoxins

Answer 15

1. Mycotoxins from molds 2. Toxic or poisonous mushrooms

Question 16

Two pronged prevention strategy

Answer 16

Prevention for staphylococcal enterotoxins; 1. Minimize contamination of food with staphylococci and/or destroy them with enterotoxin production 2. Inhibit growth of staphylococcal and/or toxin production

Question 17

Cereulid

Answer 17

Pre-formed enterotoxin; Heat stable; Usually not destroyed by reheating foods that have been stored at room temperatures

Question 18

Scrombroid Fish Poisoning

Answer 18

Bacterial-produced histamines; Proliferate after fish has been caught and allowed to remain at temperatures greater than 7.2 degrees C

Question 19

Source of mycotoxins

Answer 19

Molds, yeast, mushrooms

Question 20

Mycotoxin conditions

Answer 20

Colonization of fungi on crops; resistant to decomposition and temperature treatments; proliferate where stored foods under high humidity and warm temperatures; Cooking and drying do not destroy mushroom mycotoxins

Question 21

Most dangerous groups of mushrooms (toadstools)

Answer 21

1. Amanitas 2. False morels 3. Little brown mushrooms

Question 22

Pyrrolizidine alkaloids

Answer 22

Source: Plants; Effect: Acute liver damage and vein lesions, liver cancer

Question 23

Cyanogenic glycosides

Answer 23

Glycosides from cyanide formed by activity of hydrolytic enzymes; Source: plants; Lethal intake by humans: 0.5-3.5mg/kg body weight

Question 24

Two high food sources of cyanogenic glycosides

Answer 24

1. Lima beans (210-310mg/100g) 2. Almonds (250 mg/100g)

Question 25

Glucosinolates

Answer 25

Substances that can be considered as natural toxins; Also antinutritives; Sources: cabbage and turnips

Question 26

Biogenic amines

Answer 26

Natural toxins in plants and microbes; Source: Fruit (avocado, banana, orange, tomato, potato, pineapple)