2. Intro to Ecotoxicology

Question 1

What is ecotoxicology?

Answer 1

“Ecotoxicology is concerned with the study of the fate and effects of toxic substances in ecosystems, but its essential characteristic is to look at levels of biological organization (from molecular level to the biosphere) and the associated effects, or space-time continua (contaminant dispersion, interaction with ecological dynamics).”

Question 2

What is a chemical?

Answer 2

Any substance consisting of atoms or molecules (liquid, gas, or solid)

Question 3

What is a contaminant?

Answer 3

A substance present in greater than natural concentration as a result of human activity

Question 4

What is a pollutant?

Answer 4

A substance present in greater than natural concentration as a result of human activity, and which has a deleterious effect on living organisms

Question 5

What is xenobiotic?

Answer 5

A chemical that is foreign to a biological organism

Question 6

What is a toxicant?

Answer 6

Any toxic substance

Question 7

What is a toxin?

Answer 7

A toxicant produced by a living organism

Question 8

How did the US EPA count the amount of chemicals in commerce today?

Answer 8

risk based approach
(less cautious approach)

Question 9

How did the EU count the amount of chemicals in commerce today?

Answer 9

hazard based approach
(most cautious approach)

Question 10

How did Canada count the amount of chemicals in commerce today?

Answer 10

mixed approach

Question 11

How do we determine if chemicals are safe?

Answer 11

Standardized toxicity tests

Question 12

Characteristics of standardized toxicity tests (3)

Answer 12

• Facilitates comparisons
• Credibility
• Share data between countries

Question 13

What do these tests on animals use?

Answer 13

Key species per taxa

Question 14

What do animal testing usually test for?

Answer 14

LD50

Question 15

Types of tests (6)

Answer 15

• acute toxicity
• chronic toxicity
• genotoxicity
• carcinogenicity
• multi-generational
• development / reproduction

Question 16

What is an acute toxicity test? (4 points)

Answer 16

• Acute = short term
• Toxicity testing usually takes hours or days
• Often a high single dose
• Effects occur soon after exposure

Question 17

What is a chronic toxicity test? (4 points)

Answer 17

• Chronic = long term
• Toxicity testing usually >10% of an organism’s lifespan
• Often a lower dose or mixture
• Effects take place over a long period (years)

Question 18

What is a multi-generational toxicity test?

Answer 18

You expose one generation and study the effects on subsequent generations

Question 19

What term in the risk = exposure x hazard paradigm is LD50 associated to?

Answer 19

hazard

Question 20

How many animals are used in toxicity tests

Answer 20

1500-3000 animals for a single pharmaceutical compound related to human health

Question 21

When was the first pollution related to human activity? (aka fire)

Answer 21

125,000 years ago

Question 22

What contaminants were distributed throughout the environment during the Metal Age (approx 3000 BC)? (3)

Answer 22

• lead
• mercury
• nickel

Question 23

In 400 BC and the Middle Ages (5th-15th c.), what was the main contaminant?

Answer 23

Urban air pollution

Question 24

What was released into the atmosphere during the Industrial Revolution (1760-1840)? (4)

Answer 24

• SO2
• NO2
• smoke
• HCl

Question 25

What caused the release of those gases into the atmosphere during the Industrial Revolution?

Answer 25

Large scale burning of coal

Question 26

What was another issue during the industrial revolution?

Answer 26

The great manure crisis: 1,000,000 horses in New York City producing 1000 tonnes of manure daily

Question 27

What was an issue related to rivers during the Industrial revolution?

Answer 27

Rivers became conduits for human waste, leading to cholera and typhoid

Question 28

Why was the 1930s-1950s considered as the age of darkness for environmentalism?

Answer 28

because people were not aware of the vastness of the problems of chemicals

Question 29

When was the Great Smog of London

Answer 29

1952

Question 30

What was the Great Smog of London?

Answer 30

- Severe pollution event - So thick it was indoor as well as outdoors - 5 days of 'pea-soup' like smog blanketed the city

Question 31

What were contributing factors to the Great Smog of London? (3)

Answer 31

- heavy use of coal for heating homes - period of cold weather - windless conditions

Question 32

How many people died during the Great Smog of London?

Answer 32

4000-12,000

Question 33

What did the Great Smog of London lead to?

Answer 33

The British Clean Air Act (1956) to limit emissions. First clean air act.

Question 34

What is Silent Spring (Rachel Carlson) about?

Answer 34

How there were less birds (chicks) than in the past.

Question 35

What was associated with cross-bill in double cormorants?

Answer 35

Organochlorines

Question 36

How do contaminants change over time after bans?

Answer 36

they decrease, but there always remains a background level.

Question 37

April 22nd 1970

Answer 37

First Earth Day

Question 38

What happens in 1970-1971

Answer 38

- US EPA and Environment Canada are founded - Major Clean Air and Clean Water Acts established in both countries

Question 39

What happened in 1972?

Answer 39

- Canada/US agreement on Great Lakes Water Quality - DDT banned (insecticide)

Question 40

What is Our Stolen Future about?

Answer 40

Endocrine disruption

Question 41

What are some current trends in ecotoxicology? (4)

Answer 41

* Focus away from animal testing towards New Approach Methodologies (NAMs) ○ E.g. in vitro or in silico tests * Molecular Approaches ○ Rapid screening ○ Determining mechanism of action ○ Capturing more subtle effects * New chemical methods enable non-targeted screening and detection of Emerging Contaminants * OneHealth approach