Generalizing the safety factor approach

Safety factors (uncertainty factors) are used to avoid failure in a wide variety of practices and disciplines, in particular engineering design and toxicology. Although these two areas have similar problems in their use of safety factors, there are no signs of previous communication between the two disciplines.The present contribution aims at initiating such communications by pointing out parallel practices and joint issues between the two disciplines. These include the distinction between probabilistic variability and epistemic uncertainty, the importance of distribution tails, and the problem of countervailing risks. In conclusion, it is proposed that future research in this area should be interdisciplinary and make use of experiences from the various areas in which safety factors are used.