Ecotoxicology Flashcards
exam questions
In relation to the study of eco-toxicology, what does persistence mean? Why is it related to this field?
Persistence - The length of time that a toxin or chemical resides in the environment.
This is related because when in a highly stable environment, the substance has the opportunity to be transported to new locations.
In relation to the study of eco-toxicology, what does mobility mean? Why is it related to this field?
Mobility - The movement of pollutants, can result in unwanted contamination of local and remote ecosystems.
This can be referring to either the long term or local transport of toxic substances effectively contaminating previously pristine ecosystems or waterways and soils.
In relation to the study of eco toxicology, what does solubility mean? Why is it related to this field?
Solubility - Determines whether or not a toxin can easily dissolve.
Water soluble toxins are polar compounds, they can move easily through the environment and contaminate water supplies.
Oil/ Fat soluble toxins are non polar compounds, they can accumulate in fatty tissue and organs resulting in biomagnification.
In relation to the study of eco-toxicology, what does synergism mean? Why is it related to this field?
Synergism - A type of chemical interaction that can take place.
Chemicals combined to cause a multiplied increase in the toxicological properties.
What types of exposure are there? What are their outcomes in regards to organisms that have been exposed?
- Acute Effect - Associated with large dose, response is immediate (hours to feel effects)
Outcomes - Vomiting, convulsions, death - Chronic Effect - Low level, long term exposure (years to feel effects)
Outcomes - Organ damage
From an environmental preservation perspective, what are features of the perfect pesticide?
- A pesticide that has limited ability to affect non-target organisms (narrow spectrum)
- Does not linger or persist in the environment (easily broken down into safe material)
What is a dose response assessment?
Scientists will subject populations of test organisms to different doses of a toxin to evaluate physiological responses.
What important information is acquired from dose response assessments?
- Evaluates hazards
- Quantifies the responses that can be observed when populations are subjected to varying concentrations of a toxin.
What is the hazard quotient? How can it be used to evaluate the probability of risk?
A hazard quotient is the ratio of the potential exposure to a substance and the level at which no adverse effects are expected.
The Hazard Quotient (HQ) is equal to the Toxicological Benchmark concentration (TBC) or the Expected Environmental Concentration (EEC)
HQ = TBC/EEC
According to the hazard quotient, values that are greater than 1 are concerning because toxic effects are expected and values less than one are of lower concern because effects aren’t expected.
1< = CONCERNING
>1 = less concerning
What are the features that make DDT a highly risky toxin?
- Persistence - resides in ecosystems for extended lengths of time.
- Fat Soluble - accumulates in organic tissue; bioaccumulation.
- Chronic Effect
What are the features that make mercury a highly risky toxin?
- Persistence - resides in ecosystems for extended lengths of time.
- Fat Soluble - accumulates in organic tissue; bioaccumulation.
What is genetic resistance? Why is it related to ecotoxicology?
Genetic Resistance - the genetic makeup of an organism includes mutant genes that are not susceptible to a toxin.
This is related to ecotoxicology in terms of pesticides. When releasing a toxin to affect a population of unwanted organisms, some within the population will contain mutant genes that will have immunity to a toxin. After continual application, the mutant subset becomes the dominant genetic makeup rendering the pesticide ineffective for time.
How can genetic resistance be combated?
By using a variety of toxins to kill unwanted organisms; adding variation to reduce or minimize the resistance that can develop over time.
