Stage 4. Identification of pathway of intake for special evaluation above Level 1
Special procedures are needed for the evaluation when there is evidence for a committed effective dose of more than 1 mSv or in all cases of special monitoring. In all these cases the evaluation procedures depend to some extent on the pathway of intake. Thus, in Stage 4 the pathway of intake has to be identified.
Step 4.1: In many cases there is evidence for pure inhalation, as for example if room air contamination has been detected without detectable external contamination of the person under investigation. In those cases the special procedure for inhalation cases should be applied (Stage 5).
Step 4.2: In other cases there might be evidence for pure ingestion, as for example if contamination of the person or the working place has been detected, but not any contamination of the room air. In those cases the special procedure for ingestion cases should be applied (Stage 6).
Step 4.3: In cases where both contamination of the person or the working place and contamination of the room air is detected the pathway could be a combination of inhalation and ingestion. Such cases may be analysed as a mixture of inhalation and ingestion (Stage 7). However, a similar pattern of contamination can arise from exposure to a large aerosol (AMAD more than about 10 micrometer). Unless the aerosol in the workplace has been well characterised it will be difficult to know which is more likely, or what fraction of the intake is due to ingestion. It is therefore proposed here that pure inhalation is assumed unless there is information to justify assuming that part of the intake is ingestion.
Step 4.4: In other cases there might be evidence for direct systemic intake by injection or skin absorption. In those cases the special procedure for injection cases should be applied (Stage 8).
Step 4.5: If there is no evidence for one of the intake patterns above and if there is also no evidence for a wound deposition, then the evaluation should be started assuming pure inhalation, because this results in a conservative dose assessment.
Step 4.5.1: The evaluation of cases where wound deposition is involved is not covered by the IDEAS Guidelines at the present time.