Lecture 4 Part 1

Question 1

What is the old definition of toxicology?

Answer 1

The science of poisons

Question 2

What is the modern definition of toxicology?

Answer 2

The study of harmful interactions
between chemicals (toxic agents) and biological systems

Question 2

Define harmful and adverse effects?

Answer 2

damaging to either the survival
or normal function of the individual

Question 3

What is a toxicant?

Answer 3

is a substance that is harmful to living
organisms at low concentration because
of its detrimental effects on tissues,
organs, or biological processes

Question 4

What is environmental toxicology?

Answer 4

Is a branch of toxicology that focuses on the study of the harmful effects of chemicals on the environment and its living organisms, these chemicals show up due to humans, and it looks at how the toxicants enter and move through environmental systems and the mechanisms they use to affect the health and survival of various species

Question 5

Canadian lakes and streams contain which synthetic chemicals?

Answer 5

Antibiotics, Detergents, Plasticizers, Disinfectants, Solvents, Residues from
cosmetics and hygiene products, Pesticides

Question 6

What are the sources of chemicals in lakes and streams?

Answer 6

agricultural and urban practices

Question 7

What can happen to pollutants after they’ve entered lakes?

Answer 7

Chemicals can leach from soil into waterways due to runoff
Potential contamination and accumulation in soil
Many substances can volatilize and enter the atmosphere
Contributes to air pollution

Question 8

Are chemicals on humans?

Answer 8

yes, all of us have traces on chemicals on our bodies

Question 9

What are (5) reasons we need toxicology?

Answer 9

Protecting human health
Environmental protection
Risk assessment
Developing safer products
Responding to emergencies

Question 10

What do toxicologists do?

Answer 10

Collect data on toxic effects (toxic substances)
Find the mechanism(s) of the toxic effects (their effects)
Make predictions about the impacts of chemicals on human
populations/ environment (the probabilities of these effects)

Question 11

What are the 5 types of toxic substances?

Answer 11

Pharmaceuticals (drugs)
Food additives
Natural toxins
Household poisons
Industrial chemicals

Question 12

What are the factors affecting toxicity?

Answer 12

Dose
Duration
Route of exposure

Question 13

What are the four types of exposure?

Answer 13

Occupational exposure
Environmental exposure
Accidental poisoning
Intentional ingestion

Question 14

What is the difference between acute and chronic toxicity?

Answer 14

acute is accidental exposure once and symptoms may be reversible, chronic is continues long term exposure and is typically not reversible

Question 15

What are three routes of exposure?

Answer 15

Eating/drinking (gastrointestinal absorption)
▪ Breathing (lung absorption, e.g., H2S)
▪ Skin contact (e.g., Hg(CH3)2)

Question 16

What are four routes of removal of toxicants?

Answer 16

Urinary excretion
▪ Biliary excretion
▪ Lungs
▪ Metabolism: conversion into another species

Question 17

What three things can a toxicant go through during metabolism?

Answer 17

can be detoxified and exerted
can remain unchanged or
a potentially toxic compound can be produced (protoxicants)

Question 18

What are three steps of a toxicant metabolizing?

Answer 18

binding to a biomolecule
biochemical effects
observing effects and symptoms

Question 19

What are carbs?

Answer 19

Body’s main source of energy
▪ All contain C, H, O with the stoichiometric formula of Cn(H2O)n, hence “hydrates of carbon”
Classification of carbohydrates
Simple Carbohydrates:
▪ Monosaccharides: glucose, fructose, galactose
▪ Disaccharide: Sucrose (table sugar), Lactose (milk sugar), Mannose
▪ Complex Carbohydrates: Polysaccharides
▪ Starch
▪ Glycogen
▪ Dextrin
▪ Cellulose

Question 20

What are proteins?

Answer 20

building blocks of life. Every cell in the human body contain protein
▪ Consist of C, H, N, O, S
▪ Proteins are made of ~20 amino acids
▪ Proteins are polypeptides that fold into a fixed structure

Question 21

What are enzymes?

Answer 21

Proteinaceous compounds
Catalyst
Toxic substances such as cyanide, heavy metals, or
insecticidal parathion can alter or destruct enzymes
Destroyed or altered enzymes may not function at all or
may act improperly

Question 22

What are lipids?

Answer 22

Consist of C, H, O
▪ Most common lipids: fat and oils (triglycerides)
▪ Numerous other biological materials, including waxes, cholesterol, and some vitamins
and hormones, are classified as lipids
▪ Major component of all cell membranes are phospholipids (a class of lipids)
▪ Some toxic substances interfere with lipid metabolism, leading to detrimental
accumulation of lipids
▪ Many toxic organic compounds are poorly soluble in water, but are “lipid soluble”

Question 23

What are DNA/RNA?

Answer 23

Consist of C, H, N, O, P
▪ The essence of life is contained in deoxyribonucleic acid
(DNA)
▪ The flow of genetic information in a cell is from DNA
through RNA to proteins: “DNA makes RNA makes
protein”
▪ Store and pass on essential genetic information that controls
reproduction and protein synthesis
▪ Some chemicals can alter DNA; uncontrollable cell
production; cancer
▪ Mutagens alter DNA such that undesirable characteristics
are passed on to offspring

Question 24

What are the 8 types of toxicants?

Answer 24

Respiratory toxicants (SO2, NO2, O3, particulates)
General metabolic toxicants (CO, NO, PCBs, heavy metals: Hg, Pb, Cd, As)
Neurotoxins (parathion)
Teratogens (beverage alcohol & anti-acne drug acutance)
Mutagens (benzo(α)pyrene, O3)
Carcinogens (benzo(α)pyrene)
Immune system toxicants (formaldehyde)
Endocrine disruptors (PCBs, dioxins, several pesticides, bisphenol A)