Intro/Dose-Response Relationship Flashcards
What is environmental toxicology?
multidisciplinary study of how chemicals affect organism health and the environment
What is ecotoxicology?
the study of harmful effects of chemicals/pollutants upon ecosystems
What are two historical examples that provide the foundation for environmental toxicology?
Minamata Disease and DDT
Explain Minamata Disease
There was a factory in Minamata Bay, Japan, dumping wastes into the water. Mercury was then being transformed into methyl mercury and had harmful effects on people and animals, “cat dancing disease”
What are the direct and indirect classifications of toxicity?
Direct: result from toxic agent acting directly on the organism
Indirect: results of changes in the environment, acting indirectly on organisms
What is NOEC?
No Observed Effect concentration, “safe level” of a toxicant
What is LOEC?
Lowest Observed Effects Concentration, known as threshold effect, on an LD50 curve abt 5-10% of individuals have died
What is MATC?
Maximum Acceptable Toxicant Concentration- (NOEC + LOEC)/2
What is EC50?
The concentration that elicits 50% of expected response under defined conditions
What is IC50?
concentration that inhibits a biological process by 50%
What is a well shaped dose response curve used for?
Often seen with micronutrient tests
When are linear shaped graphs seen in dose response curves?
Cancer inducing chemicals- x axis is in log
What are the characteristics of acute toxicity testing?
must be done to a single species, over a short period of time (48-96hrs) and a high dose of chemical is given, often tests for mortality
What are the three different water conditions that can be given in acute aquatic toxicity testing and briefly explain.
static: no water movement, can impose risks as water quality decreases and could be a potential cause of death, not just toxicant
static renewal: puts organisms in fresh test solution at a given time period
flow through: constantly renews testing environment at a constant rate and medium
What are the characteristics of chronic toxicity testing?
done to a single species, low dose and length varies from 21 days to years, tests for growth and reproductive fitness
What is the acute to chronic ratio and why is it useful?
Acute LD50/MATC- can be used to predict what will happen at certain concentrations of toxicants when less chronic data is available
What is the difference between a microcosm and a mesocosm?
Microcosms are tests performed in small containers while mesocosms are tests performed in a large containers
What are the characteristics of microcosm and mesocosm testing?
involve two or more species and can have one or more toxicant, provides a more realistic overview of what happens in environment and allows for the study of interspecific interactions (i.e. food chain)
Why are field tests so important?
they allow for more realistic results of the test being as in a lab setting everything is fixed, i.e. temp, food, etc.
What are the criteria for animal models in the lab?
sensitive to a wide range of concentrations of toxicant-if this guy is safe at a certain level, majority of other organisms will be as well
widely available through laboratory culture or collection in the field
successfully maintained in lab-can breed
genetic composition and history of culture should be known-same “strain” should be used across many labs
What is a toxic unit?
defined dose of a specific toxicant- could be LD50, EC50, etc.
What is a synergistic effect of toxicants?
effects of toxicants is greater than the additive
What is an additive effect of toxicants?
effects of toxicants is the combined toxic effects of both
What is an antagonistic effect of toxicants?
effects of toxicants is less than the additives
