1. Topic 4: How Much is Too Much?

2. Pollution
A pollutant is any material that will cause harm to a living organism
Pollution is any alteration of the environment producing a condition that is harmful to living things

3. Measuring Pollution
We can measure pollution by the amount of parts of pollutant we find in a substance
Using ppm (parts per million) scientists communicate how many parts of pollutant are found in a total of one million parts of a substance
Ex. 6 ppm means 6 parts of pollution are found in 1 million parts of water
Measurements can be done in ppb (billion) or ppt (trillion)

4. Calculating PPM In order to calculate ppm, create a set of ratios
Solve for unknown
Ex.
100 = x

5. Example
There are 15 mL of DDT in mL of water. Calculate the ppm of DDT

6. Example 2
Ricin is at a concentration of 0.6 ppm in 800 mL of water. Calculate the amount of ricin in the water bottle.

7. Example 3
A fluoride solution contains fluorine at 200 ppm. How much fluoride solution can you make with 18 ml of fluorine?

8. Doses
Toxicity is the ability of a chemical to cause harm to an organism
A chemical has acute toxicity if the harm occurs after only one exposure Ex. Ricin
A chemical has chronic toxicity if the harm occurs after the chemical accumulates to a specific level after many exposures Ex. Asbestos

9. Doses Con’t
LD50 refers to the dose of a chemical that will kill 50% of a population
The lower the LD50 the less material is needed to cause high levels of harm