L1: Intro to Ecotox

Question 1

DDT

• degradability
• wildlife impacted

Answer 1

Cheap, very stable in environment
Difficult to degrade/break down –Chlorine bonds =very strong
Still used from malaria control

Concentrates through food webs which led to: songbirds dying & decline in Raptor populations (many became endangered)

Question 2

Minamata, Japan (small fishing community) & Mercury

Answer 2

Release of mercury in industrial wastewater to bay

• Mercury accumulated in shellfish and fish eaten by people
• Starting in 1950s, community showing signs of mercury poisoning (impaired walking, vision, talking, severe birth defects or death)
• Called Minamata disease

Question 3

Hierarchy of effects

Answer 3

Ecosystem
Community 
Pop
Individual
Organ, tissue, cell, biochem

Question 4

Ecosystem effects (top)

Answer 4

are hardest to identify
response lowest to toxic chemicals and their removal
difficult to link to specific chemicals

Question 5

Biochemical effects (bottom)

Answer 5

easiest to demonstrate
respond quickly to toxic chemical and its removal
links clearest to specific chemicals

Question 6

Scientific Goals of Ecotoxicology

Answer 6

To organize knowledge, based on explanatory principles, about contaminants in biosphere and effects
- Uses hypothesis testing and scientific method

Question 7

Technological Goals of Ecotoxicology

Answer 7

To develop and apply tools and methods to obtain better understanding of contaminant fate and effects

• Benefit society
• Analytical instrument, standard procedure, computational methods

Question 8

Practical Goals of Ecotoxicology

Answer 8

To apply scientific knowledge and technologies to document or solve problems such as:

• determining cause of adverse effect
• measure leaching of contaminants from waste
• monitoring improvements in local water quality

Question 9

Pollutant vs Contaminant

Answer 9

chemical or element that exceeds normal background levels and CAUSES environmental harm

chemical or element that exceeds normal background levels and it MAY or MAY NOT cause environmental harm

Question 10

Xenobiotic

Answer 10

any foreign substance, one that is not part of the normal biochemistry of organism

Question 11

Toxin vs Toxicant

Answer 11

toxic substance produced NATURALLY (by a plant or animal)

toxic substances produced by or is a by-product of HUMAN activities

Question 12

Toxicity

Toxicity of chemical

Answer 12

• effects that are damaging either to the survival or normal function of the individual

Toxicity of chemical: describes the degree to which a substance is poisonous or can cause injury

Question 13

Toxic Substances Classified by:

Answer 13

Target organ 
How it is used (pesticide, solvent, food additive)
Source
Toxic effects (embryotoxic)
Toxicity potential  
Chemical structure 
Mechanism of action or Mode of action

Question 14

Mode of toxic action

Answer 14

broad set of biological responses involving processes or biochemical pathways that are affected in an organism

Question 15

Mechanism of toxic action

Answer 15

set a molecular targets of chemical and the receptors and enzymes involved

Question 16

Agent Orange

Answer 16

Widely used during Vietnam War to defoliate plants and trees in jungle
Found contaminated with TCDD, a highly toxic by-product created during its manufacture
Led to birth defects in fetuses and cancers in children and adults including troops
Classifying Agent Orange: use (herbicide), source (aerial sprayed), effect (carcinogen)

Question 17

Factors influencing Chemical Toxicity

Answer 17

Conditions of exposure: dose, duration, route
Characteristics of chemical: uptake into body, interaction with molecules/its metabolism, breakdown in environment
Species
Environmental conditions: temperature, salinity, pH, etc.