assessment of risk

The purpose of this chapter is to introduce and demonstrate the use of a key tool for the assessment of risk. The word epidemiology is derived from Greek and its literal interpretation is ‘studies upon people’. A more usual definition, however, is the scientific study of disease patterns among populations in time and space. This chapter introduces some of the techniques used in epidemiological studies and illustrates their uses in the evaluation or setting of microbiological guidelines for recreational water, wastewater reuse and drinking water. Modern epidemiological techniques developed largely as a result of outbreak investigations of infectious disease during the nineteenth century. 136 Water Quality: Guidelines, Standards and Health Environmental epidemiology, however, has a long history dating back to Roma