Read deeper in 1757 and you will discover there are other criteria which must be facts in place to allow use of the screening values,...
Tritium does have a relatively high release value as an individual nuclide,...
Place tritium into a multiple nuclide distribution, factor in exposure pathways, and the tritium value you will see at DnD projects et al, begins to correspond with your experience on the tritium value allowed,...
Tritium is typically surrogated, albeit we can monitor for tritium as an individual nuclide in certain medias with appropriate protocols and instrumentation,...
does that help?!?!?