Introduction To Basic Toxicology

Question 1

Define xenobiotic

Answer 1

Any foreign substance to the body

Question 2

Poison

Answer 2

Agent that can cause toxicity or death, generally at low dose

Question 3

Toxins

Answer 3

Toxic compound produced by a biological agent

Question 4

What is the classification of xenobiotics?

Answer 4

Target organ classification 
According to use in public domain
According to sources
According to effects
According to physical state
According to biochemical properties

Question 5

What is defined as acute, subacute and chronic exposure?

Answer 5

<24hrs 1 exposure or up to 72 hours of low dose exposure is acute
Repeated exposure in >72 but <1 month is subacute
Continuous or repeated intermittent exposure for >3moths is chronic
Same in 1 or 3 mo is subchronic

Question 6

What is the quantal dose response?

Answer 6

Distribution of response to increasing doses in a population of test subjects

Question 7

Explain ED50, TD50, LD50 and IC50

Answer 7

ED50 (median effective dose): dose that produce a quantal effect in 50% of the population
TD50 (median toxic dose): dose that produce toxicity in 50% of pop that take it
LD50: dose that cause death in 50% of animals tested
IC50 (inhibitory concentration): concentration that inhibits 50% of measured response

Question 8

What is the threshold dose?

Answer 8

The point at which toxicity first appear

Question 9

What is NOAEL?

Answer 9

No observed adverse effect level.

Level of exposure at which there is no significant increase in adverse effect in the population

Question 10

Explain the concepts of toxicokinetics and toxicodynamics

Answer 10

Toxicokinetics: rate at which chemical enters the body, is metabolised and excreted…
Toxicodynamic: dynamic interaction of chemical with a biological target and its biological effect