8.12: LD50 and Dose Response Curve

What are Dose response studies?

Studies that expose an organism to different doses of concentrations of a chemical in order to measure the response of the organism

Independent variable of Dose response studies

concentration of the chemical

Dependent variable of dose response studies

response measured in organism

What is LD50?

refers to the dose or concentration of the chemcial that kills 50% of the population being studied

What is LD50 usually expressed as?

mass/body unit mass; ppm; mass/volume

What is a Dose Response Curve?

The data from a dose response study, graphed with percent mortality or other effect on the y-axis and dose concentration of chemical on x-axis.

What is the threshold or toxicity threshold?

The lowest dose where an effect starts to occur

What is the shape of a dose response curve?

They are S-shaped

What is ED50?

refers to the dose concentration of a toxin or chemical that causes a non-lethal effect in 50% of the population being tested.

How does the graph of ED50 compare to that of LD50?

Same general “s-shape” as LD50 dose response curve, but at lower dose concentratioins.

What are Dose Response studies tested on?

They are tested on mammals besides humans to simulate human toxicity

How is the maximum allowable dosage for humans calculated?

Divide LD50 or ED50 dose concentration by 1000 tor extreme caution

What are acute studies?

Measure effects of dose over a short period of time. They are also isolated to a lab, so they don’t measure ecological effects of organisms.

What are Chronic studies?

Longer-term studies and follow developmental impacts