Categorization of safety and risk

Risks can be categorized and ranked based on different characteristics. Such characteristics can be causes of damages or consequences or magnitudes of risks. Categorizations may improve the understanding of risks and, even more importantly, may help decision-makers to deal properly with risks in terms of risk-informed decisions. However, it has often been shown that the categorization of risks cannot be completed because the definition of risks is challenging and the size of the risks depends strongly on the choice of risk parameter and context. For example, many statistical investigations have shown that health risks are of utmost importance for human lives since 95% of all deaths in developed countries are related to health problems. Other risk studies reveal that the greatest risks to humans are social failures such as war or unemployment since many health issues are related to social failures. Such categorizations are even more difficult for emerging risks related to new technologies or current changes in social systems. For such systems, experience and therefore statistical data is still missing. Additionally, some of these systems belong to the class of complex systems with unknown causal chains.