THE NETHERLANDS WORKING GROUP ON STATISTICS AND ECOTOXICOLOGY: STATISTICS AND MODELS FOR RISK ASSESSMENT.

Nelly van der Hoeven

ECOSTAT
Vondellaan 23
2332 AA Leiden
The Netherlands
NvdH @iecostat.nl


In translation a limited set of observations in laboratory experiments to environmental standards a huge amount of problems are encountered. These have to be tackled by statistical estimation, modelling of relations, experiments to investigate these relations and estimate the model parameters, and, last but not least, by an arbitrary, political choice of the acceptable effect level.
In the Netherlands Working Group on Statistics and Ecotoxicology (www.ecostat.nl/wgSandE.htm) the current issues in statistical estimation and modelling in ecotoxicology are discussed.
The first question is how to estimate an acceptable effect level (AEL) from a laboratory experiment, that is a level (either concentration or dose) in the (laboratory) environment leading to an acceptable small effect on the species studied.
Then, with the knowledge of the acceptable effect level of a single chemical in a laboratory setting for a limited number of species, the following four questions arise:

  1. How can the AEL for all species in an ecosystem be estimated based on this limited set?
  2. What would the AEL of this chemical be if the organism is exposed simultaneously to several other (related) chemicals?
  3. How is the exposure level in the laboratory (concentration or dose) related to the exposure level in the environment?
  4. Will an environmental standard based on keeping the effect small for most species, if housed in the laboratory without inter-species interaction, lead to negligibly small effects on ecosystems?
Some discussion on the these questions will be given.

logo ECOSTAT In: Proceedings of the Jubilee Annual Meeting of the Netherlands Society of Toxicology, june 2004. p. 114