Aggregation over multiple available hazard characterisations¶
In some scenarios, it may be that for a given substance and effect there are multiple available hazard characterisations. This can happen, for instance, if there are two different NOAELs originating from different studies. In such cases, a single hazard characterisation should be derived from the available candidates.
A conservative approach is to choose the lowest hazard characterisation of the available hazard characterisations. I.e.,
HC=min
Alternatively, it is possible to aggregate the candidates into a new “average” hazard characterisation. For this, the harmonic mean, also used for obtaining central value estimates in the imputation of missing hazard characterisations, is a suitable approach.
\mathit{HC} = \left( \sum_{i}^{n} \frac{1}{\mathit{HC}_i} \right) ^{-1}