One definition of acceptable risk that has been widely accepted in environmental regulation, although is not relevant to microbiological parameters, is if lifetime exposure to a substance increases a person's chance of developing cancer by one chance in a million or less. A risk is acceptable when: (1) it falls below an arbitrary defined probability. (2) it falls below some level that is already tolerated. (3) it falls below an arbitrary defined attributable fraction of total disease burden in the community. (4) the cost of reducing the risk would exceed the costs saved. (5) the cost of reducing the risk would exceed the costs saved when the costs of suffering are also factored in: (1) the opportunity costs would be better spent on other, more pressing, public health problems. (2) public health professionals say it is acceptable. (3) the general public say it is acceptable (or more likely, do not say it is not). (4) politicians say it is acceptable. In the strict economic sense a risk is acceptable if the economic savings arising out of action to reduce a risk outweigh the cost of such action. This approach is, in effect, a simple cost-benefit analysis. (Sloman, 1994) This approach to determining acceptable risk is based on what is acceptable to the general public. In other words, a risk is acceptable when it is acceptable to the general public. (Hunter and Fewtrell, 2001)