3/30 LD50/Dose Response Curve

LD50 Paper Lab: Toxicity for Different Substances

Background
One method that scientists can use to determine the toxicity of a chemical compound is an LD50 test. This test involves introducing different dose levels of the compound to be tested to a group of experimental subjects. The most commonly used experimental subject is lab rats or mice because they have many physiologic similarities to humans.

LD50 is defined as the dose that is lethal 50% of the population (ah-ha… LD = Lethal Dose). By analyzing the LD50 for a compound and then comparing it to other known samples, scientists can get a good measurement of how dangerous it would be to the human population.

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Consider the LD50 graph of Drug X below. To find the LD50 for the compound, draw a horizontal line starting at 50% on the y-axis and ending on the graphed line, then drop a vertical dashed line from that point to the x-axis. Draw. The x-value at this point is the LD50 of Drug X.

What is the LD50 level of Drug X?

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A different drug is tested and found to have an LD50 level of 5mg/kg. Would you consider this drug to be more or less dangerous than Drug X?

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A different drug is tested and found to have an LD50 level of 5mg/kg. Would you consider this drug to be more or less dangerous than Drug X? Explain.

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Rank the following compounds in order, starting with the highest LD50 level (top), and ending with the lowest LD50 level bottom: nicotine, sodium chloride, ethanol, sucrose. (Use the chart at the end of the lab to help you.)

Sucrose
Nicotine
Ethanol
Sodium Chloride

Data Analysis
Lethal dose data is shown below for two toxic chemical compounds: arsenic and sodium cyanide. Graph each and determine their LD50 levels.

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Graph each and determine their LD50 levels. To find the Death rate (%), divide the number of deaths per dose by the total sample size. Then multiply by 100. (EX: for dose 1 [8/190=0.042 X 100 = 4.2%])

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Graph each and determine their LD50 levels. To find the Death rate (%), divide the number of deaths per dose by the total sample size. Then multiply by 100. (EX: for dose 1 [2/210=0.0095 X 100 = 0.95%])

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At what about what minimum dose is the LD50 of sodium cyanide breached?

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At what about what minimum dose is the LD50 of arsenic breached?

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Which is more dangerous based on the data, assuming that dose size is equal: arsenic, or sodium cyanide?

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Why is LD50 data so useful in dealing with human health and environmental toxins?

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In the course of measuring this data, many thousands of lab mice and rats have been killed. Do you consider this to be ethical research? Why is data collected on lab mice instead of humans? Would it be more ethical to use a species that is more closely related to us, such as chimpanzees? Explain your opinion.

Application
This is a table showing the LD50 of several substances, both toxic and non-toxic. For each substance, calculate the amount of each substance that statistically would have a 50% chance of killing you.

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Fill out the chart to determine the LD50 of several chemicals.

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LD50 stands for the

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LD50 Paper Lab: Toxicity for Different Substances

A different drug is tested and found to have an LD50 level of 5mg/kg. Would you consider this drug to be more or less dangerous than Drug X?

A different drug is tested and found to have an LD50 level of 5mg/kg. Would you consider this drug to be more or less dangerous than Drug X? Explain.

Rank the following compounds in order, starting with the highest LD50 level (top), and ending with the lowest LD50 level bottom: nicotine, sodium chloride, ethanol, sucrose. (Use the chart at the end of the lab to help you.)

Data Analysis

Lethal dose data is shown below for two toxic chemical compounds: arsenic and sodium cyanide. Graph each and determine their LD50 levels.

Graph each and determine their LD50 levels. To find the Death rate (%), divide the number of deaths per dose by the total sample size. Then multiply by 100. (EX: for dose 1 [8/190=0.042 X 100 = 4.2%])

Graph each and determine their LD50 levels. To find the Death rate (%), divide the number of deaths per dose by the total sample size. Then multiply by 100. (EX: for dose 1 [2/210=0.0095 X 100 = 0.95%])

At what about what minimum dose is the LD50 of sodium cyanide breached?

At what about what minimum dose is the LD50 of arsenic breached?

Which is more dangerous based on the data, assuming that dose size is equal: arsenic, or sodium cyanide?

Why is LD50 data so useful in dealing with human health and environmental toxins?

Application

This is a table showing the LD50 of several substances, both toxic and non-toxic. For each substance, calculate the amount of each substance that statistically would have a 50% chance of killing you.

Fill out the chart to determine the LD50 of several chemicals.

LD50 stands for the

A dose reponse curve describes