AP LD50 Toxicology Simulation

Panel 1

Simulation

Latest mortality --

Estimated LD50 Run trials

Trials 0

1. Set up

Chemical

Cohort size

5 10 20

2. Test standard concentrations

Concentration: 10 mg/mL

3. Run and record

Virtual Cohort

Select a concentration and run a trial.

Dose-Response Curve

Class Data

Trial	Chemical	Concentration	Cohort	Affected	Mortality

Panel 2

Lab Instructions

0/9 complete

Objective

Collect simulated toxicity data for every chemical, test every standard concentration, and estimate the LD50 dose in mg/kg for each chemical.

Step 1: Prepare the Test

Select the first chemical from the menu in the Simulation panel.
Choose a cohort size. Use 10 mice for a standard run or 20 mice when you want less random scatter.
Keep the same cohort size for the whole investigation unless your teacher tells you otherwise.
Read the chemical description so you know what type of substance you are testing.

Step 2: Run Standard Concentrations

For the selected chemical, start with the lowest standard concentration, 0.5 mg/mL.
Click the matching standard button, then click Run Trial.
Record the trial in the Class Data table. The table should update automatically.
Move to the next standard concentration and repeat until you have tested every standard from 0.5 to 100 mg/mL.
After all standards are tested for one chemical, select the next chemical and repeat the full standard series.
Continue until every chemical has been tested at every standard concentration.

Step 3: Improve the Data

For each chemical, find the first concentration where mortality is close to 50%.
Repeat that concentration two or three times to reduce the effect of random chance.
Repeat one concentration just below 50% mortality and one concentration just above 50% mortality.
If all points are near 0%, test higher concentrations. If all points are near 100%, test lower concentrations.

Step 4: Read the Graph

Use the x-axis to locate dose in mg/kg. The spacing is logarithmic, so equal visual spacing does not mean equal arithmetic increases.
Use the y-axis to locate percent mortality.
Find where each chemical's curve or plotted points cross 50% mortality.
Report that x-axis value as the estimated LD50 dose for that chemical.
Use the Estimated LD50 display as a check, but explain each estimate using the plotted data.

Step 5: Analyze

Answer each AP Analysis prompt using numbers from your data table.
Include the two concentrations that bracket 50% mortality for each chemical.
Compare the LD50 values to decide which chemical is most toxic in this model.
Connect your conclusion to the ethics checkpoint below.

Ethics Checkpoint

LD50 tests are historically important but ethically controversial. This model uses virtual cohorts so students can practice data analysis while discussing replacement, reduction, and refinement.

LD50 Toxicology Lab

Simulation

Virtual Cohort

Dose-Response Curve

Class Data

LD50 Investigation Submitted

Analysis Responses