The best example is the radiation exposure (X-rays, gamma-radiation or particle radiation) for which a maximum short-time-, as well as a cumulative year-, and a life-dose are well defined for every type of radiation in order to avoid cancer (e.g. maximum number of dental X-rays per year). In this case the maximum load of the definition is represented by the dose (see also Radiation Safety). A controversial field is the uses of mobile (cellular) phones, for which there are no proven damages.