A multi-criteria weight of evidence approach for deriving ecological benchmarks forradioactive substances

Abstract

Dose rate benchmarks are required in the tiered approaches used to screen outbenign exposure scenarios in radiological ecological risk assessment. Suchscreening benchmarks, namely the predicted no-effect dose rates (PNEDR), havebeen derived by applying, as far as possible, the European guidance developedfor chemicals. To derive the ecosystem level (or generic) PNEDR, radiotoxicityEDR10 data (dose rates giving a 10% effect in comparison with the control)were used to fit a species sensitivity distribution (SSD) and estimate theHDR5 (the hazardous dose rate affecting 5% of species with a 10% effect). Then, a multi-criteriaapproach was developed to justify using an assessment factor (AF) to apply to theHDR5 for estimating a PNEDR value. Several different statistical data treatments were consideredwhich all gave reasonably similar results. The suggested generic screening value of 10 µGy h − 1 (incremental dose rate) was derived using the lowest availableEDR10 value per species, an unweighted SSD, and an AF of 2 applied to the estimatedHDR5. Consideration was also given to deriving screening benchmark values for organism groupsbut this was not thought to be currently appropriate due to few relevant data beingcurrently available.