Radiation Protection Standards
Federal and state authorities set the levels of radioactivity considered safe in working environments as well as the testing procedures. However, those levels, although adequate to protect human health, are much too high to allow for uncontaminated oceanic tracer sampling. The SWAB program was, therefore, set up to test ships, etc., at contamination levels that would be much lower than health thresholds.
The staff of the Tritium Laboratory is not authorized to make a valid reference to radiation protection matters. All measurements, judgments and possible actions concerning radiation protection would have to be taken by proper health authorities. However, since we have repeatedly been asked about this, a few comments may be appropriate. The State of Florida recommends that areas be cleaned when a wipe test exceeds 1000 dpm/100 cm2. The University of Miami internal criteria are more stringent, and clean up is recommended when levels exceed twice background counts, approximately 100 dpm/100 cm2 in most cases. The standard radiation protection method for testing for spills is that of taking a square inch of filter paper and swiping a 10 x 10 cm area to be tested. Counting can be done for 14C using the filter paper directly or for 14C and 3H by suspending the paper in a cocktail for liquid scintillation. Detection levels for this would be of the order of 10 to 50 dpm. We employ a much more stringent sampling and measurement system.
The technique that we developed for the SWAB program can detect approximately 1 dpm/100 cm2, or 100 dpm/m2. The relationship (x100) between that and the health-related numbers should be remembered.