Thus if a phosphate source is introduced into the environment, these primary producers will proliferate and eutrophication may occur. Fertilizers are rich in such nitrogenous materials. The main point is that releasing untreated, nutritious materials into the environment may favor the growth of certain microorganisms, upset the normal balance of ecosystems, and kill many larger creatures that require oxygen to live, such as fish. B. Water-Borne Pathogens 1. Contamination may occur by accidental mixing of water flowing through pipes having treated and untreated water.
Many countries have poor or non-existent water treatment facilities.
It is wise to avoid the various sources of polluted water. The drinking water may contain potentially hazardous pathogens. In addition, vegetables washed in water, and shellfish that concentrate the microorganisms from the polluted waters in which they live, may be trouble. Boiling water at 100 o C for ten minutes will exterminate virtually all contaminating pathogens. Inoculation against specific pathogens provides immunity against infection.