SELL
DIOACTIVITY IN AGRICULTURAL PRODUCTS
extent to which radioactivity is transferred to the critical foods must be
recorded so that any sites of potentially high contamination can be given
special consideration.
OF SURVEY
9 this paper that the object of
‘ar reactors is to satisfy both the
nacceptable quantities of radio-
B.
widely spaced as possible, in both the inner and outer zones. If the wind is
ca eee creFT
ite surveys should be expanded
timary purpose in the hope of
od chain mechanisms. While it
possible to combine these two
d be emphasized. It is unlikely
lechanisms, or on the movement
obtained unless the investigation
urposes and elaborate methods
1 that agricultural and meteoroed if interpretations are to be
should be examined.
real the sites at which critical
‘tors which may influence the
C.
Frequency and Bulking of Milk Samples
is desirable, for example, once every two weeks, Analyses of iodine 131
must be carried out after each collection because of its rapid decay. For
er
the assay of strontium 90 it would, however, be appropriate to bulk samples
over periods of up to 3 months. Assuming that negligible or low levels of
radioactivity are released, and the analytical procedures are sufficiently
accurate, it may be reasonable to combine samples from different sites in
each sampling zone. If, for example, the produce of five farms were combined and the radioactivity in the bulked sample was shownto be not more
than one fifth of the specified Ievels it would be established that an
unacceptable level did not occur on any farm.
sment of the mode of operation
at nuclides merit investigation,
ishment the maximum deposit
: beyond which no appreciable
ing zones, the nature of agri-
coverage in the two zones may necessitate some adjustment of their
boundaries. Since milk is the critical food for both iodine 131 and strontium
90, farms producing milk will normally be the chosen samplingsites.
Because the levels of iodine 131 and stronttum 90 in milk reflect con-
lanning of Surveys
were indeed necessary. It is
the conclusion that environ-
usually in one direction it may be appropriate to pay special consideration
to farms in the downwindsector. In practice, the obtaining of adequate
tamination of pastures only in the previous few days, frequent sampling
| determined, it is important to
be obtained with the minimum
‘stions, made with this aim in
cpose of which is to ascertain
‘ed:
Ud be appropriate to consider
Selection of Sampling Sites
The aim is to select a number, possibly 4-6, sampling sites, which are as
..
surveys in emergencies present
‘ems which are not considered
D.
Sampling of Materials Other than Milk
If it were judged necessary to consider the possible release of strontium
®
90 in sparingly soluble particles, sampling of herbage and the root mat
a
n this way “inner” and “outer”
n of the levels of activity found
the contamination due to the
es from world-wide fallout or
atters leads to the conclusion
ilways be adequately detected
9
should be undertaken at annual intervals at each sampling site so that the
total deposit per unit area can be investigated. More frequent sampling
for this purpose lacks justification in normal circumstances, both because
of the long integrating period on the ground surface and because tissue
doses are assessed as annual averages.
Sometimes, owing to climatic factors, the supply of milk may cease for
part of the year. If it ts judged necessary to consider the possible contamination of diet during such periods the most convenient procedure may
be to sample the type of grass which cattle would consume and infer the
levels in milk which would arise from knowledgeof the relationship between
the contamination of herbage and that of milk. If this procedure indicates
that radioactivity in the milk would not have exceeded an acceptable level
a
vs