Toxicology Flashcards
Acute exposure
Short term exposure, usually 96 hours
Chronic exposure
Exposure across an organism’s whole life
Which type of mercury is toxic?
Methylmercury
Median tolerance limit
Tolerance limit corresponding to 50% survival (TL50)
Median survival time
The time half of the organisms in a sample are able to survive a given level of stress
Incipient lethal levels
The concentration of toxicant corresponding to an infinite median survival time
Criterion maximum concentration
The 1 hour average concentration that is not to be exceeded more than once every 3 years
Criterion continuous concentration
4 day average concentration not to be exceeded more than once every 3 years
Water hardness
A measure of calcium and magnesium ions in water
Chronic toxicity unit
=accute toxicity unit x accute/chronic ratio
Accute toxicity unit
Concentration of substance / 96 hour TLM
Antagonistic
Toxicity of a mixture A&B is less than the toxicity of only substance A or substance B alone
Strictly additive
Percentage of dead organisms exposed to mixture A&B is exactly as expected if water contained only A or only B
Supra-additive
Mixture of A&B is more toxic than A or B alone
Infra-additive
Percentage of organisms dead after 96 hours is greater than 50% but less than A or B alone
