Assessing ecological effects of radionuclides: data gaps and extrapolation issues

Abstract

By inspection of the FASSET database on radiation effects on non-human biota, one of the major difficulties in the implementation of ecological risk assessments for radioactive pollutants is found to be the lack of data for chronic low-level exposure. A critical review is provided of a number of extrapolation issues that arise in undertaking an ecological risk assessment: acute versus chronic exposure regime; radiation quality including relative biological effectiveness and radiation weighting factors; biological effects from an individual to a population level, including radiosensitivity and lifestyle variations throughout the life cycle; single radionuclide versus multi-contaminants. The specificities of the environmental situations of interest (mainly chronic low-level exposure regimes) emphasise the importance of reproductive parameters governing the demography of the population within a given ecosystem and, as a consequence, the structure and functioning of that ecosystem. As an operational conclusion to keep in mind for any site-specific risk assessment, the present state-of-the-art on extrapolation issues allows us to grade the magnitude of the uncertainties as follows: one species to another > acute to chronic = external to internal = mixture of stressors > individual to population > ecosystem structure to function.

Histological variations in liver of freshwater fish Oreochromis mossambicus exposed to 60Co gamma irradiation

“…One problem in adapting ERA to the case of radioactive substances relates to the lack of data describing effects of chronic exposure to low levels of radiation for non-human species (Garnier-Laplace et al, 2004).…”

Effects of radioactive contamination on Scots pines in the remote period after the Chernobyl accident

“…To properly understand the effects of normal, real-world contaminant exposures, one must consider actual field conditions. However, for most wildlife groups and endpoints there are very few studies that link accumulation, chronic exposure and biological effects in natural settings (Garnier-Laplace et al 2004).…”

Effects of radioactive contamination on plant populations and radiological protection of the environment

“…Nevertheless, up to now there is a distinct lack of quantitative data [1] on the real longterm biological consequences of chronic radiation exposure lasting a long period of time, in particular, at the population level. Actually, very few studies exist that are directly relevant to understanding the responses of plant and animal populations to radionuclides in their natural environments.…”