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.
Question 1
1.
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.
Identify the LD50 level of Drug X?
Question 2
2.
Question 3
3.
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.
Question 4
4.
Data Analysis
Lethal dose data is shown below for two toxic chemical compounds: arsenic and sodium cyanide. Graph each and determine their LD50 levels.
Question 5
5.
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%])
Question 6
6.
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%])
Question 7
7.
Question 8
8.
Question 9
9.
Question 10
10.
Explain why LD50 data is so useful in dealing with human health and environmental toxins.
Question 11
11.
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.
Question 12
12.
Question 13
13.
Question 14
14.
Question 15
15.
Question 16
16.
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?
More dangerous
Less dangerous
Rank the following compounds in order, starting with the highestLD50 level (top), and ending with the lowest LD50 level bottom: nicotine, sodium chloride, ethanol, sucrose.
Sodium Chloride
Nicotine
Sucrose
Ethanol
At about what minimum dose is the LD50 of sodium cyanide breached?
4 doses
6 doses
8 doses
10 doses
At about what minimum dose is the LD50 of arsenic breached?
8 doses
10 doses
13 doses
16 doses
Which is more dangerous based on the data, assuming that dose size is equal: arsenic, or sodium cyanide?
Arsenic
Sodium cyandide
Equal
LD50 stands for the
Dose (amount) of a chemical that is lethal (deadly) to 100% of the population of a particular species
Dose (amount) of a chemical that is lethal (deadly) to 50% of the population of a particular species
Dose (amount) of a chemical that is harmful to 100% of the population of a particular species
Dose (amount) of a chemical that is harmful to 50% of the population of a particular species
A dose reponse curve describes
The effect on an organism or mortality rate in a population based on the dose of a drug or toxin
Dose (amount) of a chemical that is letal (deadly) to 50% of the population of a particular species
The effect on an organism or mortality rate in a population based on the percentage of the organism that dies
The effect on an organism or mortality rate in a population based on the percentage of the organism that gets sick
The graph below represents the dose response curves of insect pests for four different pesticides.
The United States Environmental Protection Agency has determined that all four pesticides could have negative health consequences to humans if applied at high concentrations and has set a maximum application concentration of 500g/cm3. Based on the data in the graph, which pesticide would be the most effective at that concentration?
A
B
C
D
The graph below represents the dose response curves of insect pests for four different pesticides.
Other than potential negative health effects on humans, which of the following is a disadvantage of using chemical pesticides to eliminate crop pests?
Crops grow more quickly without pests present, taking up water quickly and leading to salinization of soils.
Pests and other organisms affected by the pesticide are permanently removed from the area where the pesticide is applied.
Pesticides may harm organisms other than the target crop pests through biomagnification in the food web.
Extensive use of pesticides accelerates the rate at which succession occurs in agricultural areas.
The graph below represents the dose response curves of insect pests for four different pesticides.
A farmer needs to kill more than half of the insect crop pests to ensure a profitable harvest. Based on the graph, what is the minimum concentration of pesticide C that the farmer must use to make a profit?