4. Estimate of the fraction of the production of Oak Ridge National 
Laboratories shipped to other than AEC operations, that became wastes 
for sea disposal. 
During the period January 1956 to September 1957, ORNL shipped 
approximately 50,000 curies, measured at the time of shipment, for use 
by non-AEC facilities. Of this total, approximately 28,759 curies were 
isotopes with short half lives, while isotopes of strontium, cobalt, ce- 
sium, iron, and zinc amounted to 21,141 curies, of which 21,020 were 
shipped as ''sealed sources'', Assuming that sealed sources (cobalt 
bars, for example, used as radiation sources) will not find their way 
into commercial disposal routes when their initial usefulness has passed, 
121 curies of long-lived isotopes appear as the potential supply that 
might have arrived at dockside for disposal at sea. During the same 
period, an estimated 25 curies (composition doubtful) was actually dis- 
posed of at sea. 
If the assumption concerning the fate of ''sealed sources" is cor- 
rect and if the estimate of 25 curies disposed of at sea is correct, then 
approximately 20% of the ORNL shipments of "hazardous isotopes"! to 
non-AEC users will eventually appear as wastes for sea disposal. 
PREVIOUS STUDIES 
Several studies have been made since 1950 that are either directly 
or indirectly concerned with the disposal of radioactive substances 
into the sea. The first of these, published as U.S. Bureau of Standards 
Handbook 52 (3) lists the quantities of each of a number of radioisotopes 
that can be retained safely in the body, as well as the concentration of 
each isotope that can be tolerated in drinking water and in air. The 
maximum permissible body burden, drinking water and air concentra- 
tions are considered to be the levels below which no readily detectable 
biological damage will occur in man under conditions of continual ex- 
posure at those levels. 
Although the recommendations contained in Handbook 52 were 
based upon the best biological and radiological evidence available, the 
authors note that in several cases the evidence available to them was 
scant and that the maximum permissible concentration levels should be 
revised as new evidence becomes available. In this connection Looney 
(9) suggested that the accepted level for radium, which forms the basis 
(in part) for the calculation of the permissible levels of other isotopes, 
is too high and recommends that the radium level be lowered until more 
information becomes available on the effects of radium in man over a 
normal lifetime. 
In calculations made later in this report, the recommended maxi- 
mum permissible levels in Handbook 52 have been used. We realize 
that man does not drink seawater; however, the Handbook 52 values give 
a basis for estimating the maximum permissible rate of ingestion of 
radionuclides that may be contained in marine food products. 
