2. Intro to Ecotoxicology Flashcards
What is ecotoxicology?
“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).”
What is a chemical?
Any substance consisting of atoms or molecules (liquid, gas, or solid)
What is a contaminant?
A substance present in greater than natural concentration as a result of human activity
What is a pollutant?
A substance present in greater than natural concentration as a result of human activity, and which has a deleterious effect on living organisms
What is xenobiotic?
A chemical that is foreign to a biological organism
What is a toxicant?
Any toxic substance
What is a toxin?
A toxicant produced by a living organism
How did the US EPA count the amount of chemicals in commerce today?
risk based approach
(less cautious approach)
How did the EU count the amount of chemicals in commerce today?
hazard based approach
(most cautious approach)
How did Canada count the amount of chemicals in commerce today?
mixed approach
How do we determine if chemicals are safe?
Standardized toxicity tests
Characteristics of standardized toxicity tests (3)
- Facilitates comparisons
- Credibility
- Share data between countries
What do these tests on animals use?
Key species per taxa
What do animal testing usually test for?
LD50
Types of tests (6)
- acute toxicity
- chronic toxicity
- genotoxicity
- carcinogenicity
- multi-generational
- development / reproduction
What is an acute toxicity test? (4 points)
- Acute = short term
- Toxicity testing usually takes hours or days
- Often a high single dose
- Effects occur soon after exposure
What is a chronic toxicity test? (4 points)
- 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)
What is a multi-generational toxicity test?
You expose one generation and study the effects on subsequent generations
What term in the risk = exposure x hazard paradigm is LD50 associated to?
hazard
How many animals are used in toxicity tests
1500-3000 animals for a single pharmaceutical compound related to human health
When was the first pollution related to human activity? (aka fire)
125,000 years ago
What contaminants were distributed throughout the environment during the Metal Age (approx 3000 BC)? (3)
- lead
- mercury
- nickel
In 400 BC and the Middle Ages (5th-15th c.), what was the main contaminant?
Urban air pollution
What was released into the atmosphere during the Industrial Revolution (1760-1840)? (4)
- SO2
- NO2
- smoke
- HCl
What caused the release of those gases into the atmosphere during the Industrial Revolution?
Large scale burning of coal
What was another issue during the industrial revolution?
The great manure crisis: 1,000,000 horses in New York City producing 1000 tonnes of manure daily
What was an issue related to rivers during the Industrial revolution?
Rivers became conduits for human waste, leading to cholera and typhoid
Why was the 1930s-1950s considered as the age of darkness for environmentalism?
because people were not aware of the vastness of the problems of chemicals
When was the Great Smog of London
1952
What was the Great Smog of London?
- Severe pollution event
- So thick it was indoor as well as outdoors
- 5 days of ‘pea-soup’ like smog blanketed the city
What were contributing factors to the Great Smog of London? (3)
- heavy use of coal for heating homes
- period of cold weather
- windless conditions
How many people died during the Great Smog of London?
4000-12,000
What did the Great Smog of London lead to?
The British Clean Air Act (1956) to limit emissions.
First clean air act.
What is Silent Spring (Rachel Carlson) about?
How there were less birds (chicks) than in the past.
What was associated with cross-bill in double cormorants?
Organochlorines
How do contaminants change over time after bans?
they decrease, but there always remains a background level.
April 22nd 1970
First Earth Day
What happens in 1970-1971
- US EPA and Environment Canada are founded
- Major Clean Air and Clean Water Acts established in both countries
What happened in 1972?
- Canada/US agreement on Great Lakes Water Quality
- DDT banned (insecticide)
What is Our Stolen Future about?
Endocrine disruption
What are some current trends in ecotoxicology? (4)
- 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
