Unit 8-Environmental Heath Ecotoxicology Flashcards
What is ecotoxicology?
The study of toxins and their effects on organisms, and the environmental factors that influence exposure
What is one of the most common uses of toxins and is a basis for ecotoxicological studies?
Pesticides: It’s development, testing, and use
Pesticides are used to?
Protect crops, animals, and humans from damage and disease caused by “pests” and to remove weeds.
ex: herbicide, rodenticide, fungicide, insecticide
What is a pest?
An undesirable competitor that interferes with human welfare/activities
**What are the factors that affect toxicity of substances in the environment?
- Persistance
-How long a chemical takes to break down in the environment - Solubility
-The ability of a chemical to dissolve in liquid - Bioaccumulation and biomagnification
-The build up of fat soluble chemicals in the body over time
_____ can be excreted from your body but may easily enter and accumulate in aquatic ecosystems
Water-soluble
_____ are absorbed into fatty tissues and build up in bodies
Fat -soluble
How is the food-chain/food-web affected by bioaccumulation/magnification?
Bioaccumulation leads to build up in each trophic level
Animals higher in the food web accumulate more toxins
**What factors affect toxicity?
1. Acute exposure
-Large exposure
-Symptoms develop rapidly
**What factors affect toxicity?
2. Chronic exposure
-Low-level exposure
-Takes place over a long period of time
-prolonged exposure
**What factors affect toxicity?
3. Age and sex
-Young and old are more susceptible
-Hormones interact with toxins
**What factors affect toxicity?
4. Antagonistic Effect
-Chemicals interact and cancel out/lessen the toxicity
**What factors affect toxicity?
5. Synergistic Effect
-Chemicals interact to create a pronounced effect and greater response than would be expected
ex: Nicotine + Asbestos increase cancer
Do toxins differ from their intended pathway in an ecosystem?
YES
A very low % reaches its target
98% can end up in air surface water, groundwater, or bottom sediments
What is the Mobility and Long Range Transport of (Air) Pollutants (LRTAP) also called? What is this effect?
The Grasshopper Effect because pollutants leap towards the poles with air currents
Substances are transported by wind and water and end up far away from the source
-ex: the arctic having the highest mercury concentrations
What does broadcast spraying/crop dusting result in?
Exposure of non-target species
What are indirect ecotoxicological stresses?
Changes in habitat due to purposely released toxins
-ex: herbicides kill plants, depriving herbivores of their preferred foods
What is Genetic Resistance/Genetic Based Tolerance?
Mutant individuals are resistant to a pesticide. The mutant survives and contributes to the new population until eventually the mutant gene becomes dominant. Higher concentrations/new pesticides are required to affect the population
How do you reduce resistance?
With active ingredients, rotating herbicides, and having multiple modes of action
What is a risk?
The probability that exposure to a substance will be harmful
**What are the factors of a risk assessment?
- Dose (determined in lab)
-The amount that enters the body - Exposure assessment (tested in the environment)
- Risk characterization (whether it poses a risk or not)
What is a lethal dose?
Causes death
ex: LD50 causes death to 50% of the population
What is a sub-lethal dose?
Has a measurable effect that is not death
What is an effective dose?
Causes a specific response
ex: ED50 causes 50% of the population to exhibit a response
