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Unexplained Episodes:
‘Firure l reveals two other isolated periods (4 and 6) of slightly
elevased isolated radioiodine concentrations in the PMY that nave not
been previously discussed.
From Novenber 30 to Decenber 8, 1965,
eleven milxsheds in the southeastern U. S. (Baltimore, Md. to Tampa, Fla.
to Little Rock, Ark.) reported concentrations between 14 and 36 pCi/l.
Reanalysis of the gamme spectra for the detectable values during the
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November 30 - December 8, 1965 period confirmed the presence of radioiodine as originally reported.
‘The Savannah River and Oak Ridge Atomic
Energy Commission installations lie in this area and mere proximity suggests
them as possible sources.
However, neither their local monitoring results
nor reported zis releases, if any, implicate either plant.
The other
period, July 1966, followed the South Pacific atmospheric tests.
of 60 pCi/L was observed at Palmer, Alaska, on July 19, 1966.
A value
But itis
.
deemed unlikely that an Alaskan milkshed would be contaminated by a source
at 22°S.
There is, however, no independent evidence for accepting or
rejecting southern hemisphere nuclear tests for the several elevated yi3l
milk concentrations in 1966.
In addition to the two unexplained periods in November-December 1965
and July 1966, there are others diring which the radioiodine concentrations
exceeded 10 pCi/l but failed to reach 30 pCi/1l, most lying close to the
lower value.
These concentrations do not, a of course, ? appear on Fig. l.
in all of these latter cases the geographical and temporal distribution
or milxsheds appears to ve almost random.
These relatively few concen-
trations above 10 pCi/l might be expected as statistical fluctuations
.because of the routine handling and analysis of the many thousands of
sanoles.
Commerison of PMN with State milk network
,
In addition to the PMN, about 40 states monitor zist in milk.
In 1963
only 11 states reported to the FHS, which publishes their results in the
Radiological Health Data and Reports (21).
reporting had increased to fifteen.
By 1968 the number of states
Many of the state networks collect
and analyze milk samples on @ monthiy basis wnile some collect more
frequently.
Neill and Snavely (22) summarized the criteria used by the
states in their milk samvling
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