Ecotoxicology Flashcards
What is a toxicant?
chemical that has an effect on an organism
What is a toxin?
substance produced by a living organism which is poisonous at a certain level
What does hydrophobic mean?
substance that repels water or will not dissolve in water
What does hydrophilic mean?
substance that will easily dissolve in water
What does xenobiotic mean?
man-made chemical found in a biological system that is not naturally found there
What is poison?
substance that can cause biological disturbances to a living organism at a certain dosage
What is a dose?
quantity of drug to be administered all at one time or over a given period of time
What makes a chemical poisonous?
the dosage
- Lethal Dose Fifty (LD50) is one way the _____ of chemicals are measured.
- What is LD50?
- How is LD50 measured?
- toxicity
- amount of a toxicant required to kill half (50%) of a population
- mg of toxicant/kg of animal’s body weight
- What is Lethal Concentration 50 (LC50)?
2. How is LC50 measured?
- Concentration of a toxicant in an environment which produces death in 50% of a population
- mg of substance/L of air or water
- What is Toxic Dose 50 (TD50)?
- The _______ the TD50, the more toxic the chemical is.
- What does NOEL stand for and what does it mean?
- dosage that produces toxic effects in 50% of the population
- lower
- No Observable Effect Level: highest dose of a toxicant that produces no noticeable toxic effect on animals
What are the three ways chemicals can enter the body?
- Ingestion
- Inhalation
- Absorption
The skin is a major barrier that protects agaisnt chemicals. What is its main layer of defense?
Stratum corneum
- What is the stratum corneum?
2. Why is it used as a defense agaisnt chemicals?
- Thick layer of dead and flattened skin cells
2. Water-proof, contains the protein keratin which allows for protection agaisnt damage
What do the kidneys do to prevent toxicity?
Allows toxicants to be excreted via the urine
What does the liver produce and how does this help to prevent toxicity?
Bile. Toxicants get stored into the bile and released in the feces
What is the “first pass effect”?
When a toxicant absorbed by the gastrointestinal tract must first go to the liver before it enters the body circulation
How do proteins help prevent toxicity?
bind to toxicants and eliminate them
What is bio accumulation?
the degree to which a toxicant can accumulate in a living organism (through inhalation, ingestion, and dermal exposure).
when an organism takes in a toxic substance faster faster than it is expelled and it accumulates in tissue
The degree of bio accumulation depends on the rate of _____ versus the rate at which an organism is capable of _____ and _____ the toxicant.
intake
breaking down
eliminating
- What does Kow stand for?
- What is it used for?
- What is the formula?
- Why octanol?
- Octanol-Water Partition Coefficient
- Used in environmental studies to determine the fate of chemicals in the environment
- How well the toxicant dissolves in octanol/how well the toxicant dissolves in water
- octanol is similar to fat tissues (the more it dissolves in fat the more it bio acumulates)
- What is bio concentration?
2. What is a bio concentration factor?
- the uptake of a substance to concentrations in the tissues of an organism that are greater than in the surrounding
environment - concentration of chemical in tissue/concentration in water
What is bio magnification?
The increase in concentration of a toxicant as it passes through to higher levels of a food web
DDT was the first insectice to come into widcespread agricultural use. What were the benefits of it?
- Penetrates the insect
- Enters the cells, binds to nerves, causes death
- Toxicity low in humans and animals because tissues absorb less
- Does not wash away easily
How did DDT impact ecosystems?
- Kill mosquito=> parasitic wasp died=> overpopulation of caterpillars=> caterpillars ate the roofs off the villagers houses
- DDT accumulated in geckos=> cats ate geckos and died=> rat population flourished=> outbreak of plague
What is environmental remediation?
process of decontaminating soil or water
What is mechanical remediation?
excavating (pumping) all the soil in an area so that it can be filtered or chemically treated
What is biodegration?
breaking down of organic matter into inorganic matter by microorganisms and fungi
What is bioremediation?
use of microorganisms to clean up a polluted site
What is phytoremediation?
use of plants to eliminate contaminants from a polluted site
