13. The process for applying the guidance levels shall be established as shown in Figure 1.
(a) The screening levels are the total radioactivity present in the form of alpha and beta radiation in drinking-water. They represent activity concentrations below which no further action is re-quired and are based on the IDC of 0.1 mSv per year.
(b) The gross alpha and gross beta screening methods rely on the detection of emitted alpha or beta particles during radioactive decay of the radionuclides. They are appropriate for most situations in which radionuclides in drinking-water are likely to be found, as they detect natu-rally occurring radionuclides.
(c) The guidance levels shall be used as a trigger for further investigation and not be interpreted as a limit indicating that the drinking-water is unsafe.
(d) The guidance levels shall not apply in emergency exposure situations.