A chemical which contaminates the environment is called a pollutant. Examples of these are:
These types of pollutants affect organisms by a process called bioaccumulation.
Here is one way pollutants can enter a food chain.
DDT is a chemical pesticide which was used by farmers to control insect pests eating their crops. It can be used to demonstrate bioaccumulation as shown in this diagram.
The high concentrations of DDT in birds of prey weakened their egg shells, their young died and populations decreased.
To the nearest whole number, how many times greater is the concentration of DDT in the birds of prey than in the water?
25 ÷ 0.000003 = 8,333,333
Write the number given as the answer to the question above in words.
Eight million, three hundred and thirty three thousand, three hundred and thirty three.