Occupational Intakes of Radionuclides Part 1 - ICRP

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DRAFT REPORT FOR CONSULTATION
retained in the body for long periods; occasional measurements may be made to
confirm the absence of build-up of activity within the body.
5.3.3 Special or Task-Related Monitoring
(291) Monitoring in relation to a particular task or event may often involve a
combination of techniques so as to make the best possible evaluation of a novel or
unusual situation. Since both special and task-related monitoring relate to distinct
events, either real or suspected, one of the problems encountered in interpretation of
routine monitoring results does not apply, viz. the time of intake is known.
Furthermore, there may be more specific information about the physical and chemical
form of the contaminant.
(292) In some cases of suspected incidents, screening techniques (such as measuring
nose blow samples or nasal smears) may be employed to give a preliminary estimate
of the seriousness of the incident. In these cases the regional deposition in the nose
can be used to confirm that an intake has occurred and to give a rough estimate of the
intake. Positive nasal swabs should trigger special bioassay measurements (Guilmette
et al, 2007).
(293) If therapeutic procedures have been applied to enhance the rate of elimination
of a radionuclide from the body then special monitoring may be needed to follow its
retention in the body and to provide the basis for a dose assessment. In cases where
treatment has been given, care must be taken in selecting the monitoring methods
because normal biokinetics of the radionuclides can be altered significantly. For
example Prussian Blue enhances the faecal elimination of radioisotopes of caesium
and therefore faeces bioassay, although not used routinely, should be implemented in
addition to in vivo and urine monitoring.
(294) Following a cut or wound, some radioactive material may penetrate to
subcutaneous tissue and hence be taken up by body fluids and distributed around the
body. Depending upon the radionuclide(s) and the amount of activity it may be
necessary to undertake a medical investigation and a programme of special
monitoring. In these circumstances, the amount of radioactive material at the site of
the wound should be determined taking into account self-attenuation of the radiation
in the foreign material and in tissue, as an aid to decisions on the need for excision. If
an attempt is made to remove material from the wound, measurements should be
made of the activity recovered and remaining at the wound site, so as to maintain an
activity balance. The excised material can also provide information on the isotopic
ratios and physico-chemical composition which can inform the dose assessment. A
series of further measurements may also be needed to determine any further uptake to
blood and body tissues from which any additional committed effective dose can be
calculated.
5.4 Derived Investigation Levels
(295) In many situations of potential exposure to radionuclides, it is convenient to
set derived investigation levels (DIL) for the quantities that are measured in
monitoring programmes, i.e. whole body content, organ content, daily urinary or
faecal excretion, activity concentration in air. The chosen value for the DIL may be
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