Animal Waste, Water Quality and Human Health

10Comparative risk analysisGraham McBride, Tom Ross and Al Dufour10.1 ESSENTIALS OF RISK ASSESSMENTRisk assessment is a systematic process to estimate the level of risk related to somespecific action or activity. It is now commonly applied to a wide variety of humanendeavours in which harm to people, the environment or economic interests mightoccur. In the context of public health, the process attempts to quantify thelikelihood and severity of illness to individuals or populations from aspecified hazard.The primary purpose of risk assessment is to provide support for decisions aboutmanaging risks associated with those specific actions or activities. This is done bysystematically synthesizing information about the factors that contribute to the riskin a coherent framework that enables risk, or relative risk, to be inferred fromknowledge of those risk-contributing factors in specific circumstances.Depending on the needs of the risk manager, the risk assessment may attempt toassess the relative effectiveness of proposed risk mitigations, or to estimate the© 2012 World Health Organization (WHO). Animal Waste, Water Quality and Human Health. Editedby Al Dufour, Jamie Bartram, Robert Bos and Victor Gannon. ISBN: 9781780401232. Published byIWA Publishing, London, UK.