Transforming Acute Ecotoxicity Data into Chronic Data: A Statistical Method to Better Inform the Radiological Risk for Nonhuman Species

Ecotoxicity
data constitute the basic information to support the
derivation of ecological benchmark values, whatever the stressor concerned.
However, the set of appropriate data may be limited, especially with
regard to chronic exposure conditions. The available data are often
biased in favor of acute data from laboratory-controlled conditions,
much easier to acquire. To make the best use of the available knowledge
and better inform the effects of ionizing radiation chronic exposure
on nonhuman species, we investigated the transposition to ionizing
radiation ecotoxicity of one method proposed for chemicals to extrapolate
chronic information from acute toxicity data. Such a method would
contribute to enriching chronic data sets required for the derivation
of benchmark values, making them more robust when used as reference
values for ecological risk assessment. We developed accordingly the
Acute to Chronic Transformation for Radiotoxicity data (ACTR) approach,
which we validated. We introduced then the new concept of Endpoint
Sensitivity Distribution (ESD). This finally allowed us to compare
purely chronic and ACTR-built ESDs for different taxa. For some of
them, the predicted and observed distributions looked very similar.
This promising ACTR method appeared applicable with a reasonable level
of confidence, but its generalization asks for improvements, some
being already identified.