Extent of absorption. The total quantities of radioactivity shall be de- termined for excerta collected daily for 7 days or until at least 90 percent of the radioactivity has been recovered in the excreta.
Extent of absorption. T h e t o t a l q u a n t i t ies of r a dio a c t ivi t y s h a ll be de- t e r m i n ed fo r exc r e t a collec t ed d a il y fo r 7 d a y s, o r af t e r a t le a s t 90 pe r ce n t of t h e r a dio a c t ivi t y h a s bee n r ecove r ed i n t h e exc r e t a , w h ic h eve r occ ur s fi r s t .
