Stage 3. Standard evaluation procedure at Level 1


Having determined the measured value (M) to be due to a new intake, the intake and dose are evaluated from the net value N = M – P using a priori parameters. If the dose turns out to be above 1 mSv, the evaluation should be repeated according to Stage 4, in order to adjust the a priori parameters if necessary. The standard evaluation procedure should be applied only for routine monitoring.


Step 3.1: If the measured value is not due to routine monitoring, special evaluation procedures (Stage 4) are needed anyway.


Step 3.2: The pathway of intake is identified. In routine monitoring situations the pathway will most likely be inhalation, but it could also be ingestion or a combination of inhalation and ingestion. However, ingestion should be assumed only in those cases where there is clear evidence for this pathway (well established and documented). Otherwise the inhalation pathway should be assumed.


Step 3.3: Case or site specific parameter values should be assigned as far as they are available. Such a priori information needs to be well established and documented. Examples might include the Activity Median Aerodynamic Diameter, AMAD, (if it has been determined by appropriate air sampling, e.g., cascade impactor), specific absorption parameter values (if the inhaled material is sufficiently well characterised), or the time of intake (if potential exposure was limited, or an incident was known to occur).  Otherwise the following default parameter values should be used:

 

  • Mode of intake: Single intake
  • Time of intake: Mid-point of the monitoring interval, i.e. the mid-point of the time range between the date of the measurement being considered and the date of either the previous measurement or the beginning of monitoring
  • Inhalation:
    • Absorption Type and f1 value: defaults according to ICRP Publication 68, Annexe F (Table 3.3). If the compound is unknown, then for those elements where there is a choice of absorption Types, the Type for “unspecified compounds” should be used, if available. For uranium, “unspecified compounds” are not listed, and it is proposed that Type M is assumed in the absence of specific information, as in ICRP Publication 71.
    • Particle size: 5 um AMAD
  • Ingestion:
    • f1 value: defaults according to ICRP Publication 68, Annexe E.

 

Step 3.4: Using the assigned a priori parameter values, the intake is estimated by dividing the net value N = M – P by the appropriate retention or excretion function. Using the same assigned a priori parameter values the committed effective dose is calculated by multiplying the evaluated intake by the appropriate dose coefficient (dose per unit intake).

 

 

Step 3.5: If the dose is less than 1 mSv, there is no need for further investigation (Step 3.5.1). Otherwise special procedures (Stage 4) are needed for more detailed evaluation of the case.

 

 

Step 3.5.1: The results in terms of intake and committed effective dose from Step 3.5 are recorded together with the corresponding parameter values from Step 3.3.