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Review and validation of bioaccumulation models

Case study – Environment Agency


The Environment Agency has a need to derive standards in all media for the protection of the environment and human health in order to fulfil its statutory pollution control functions.

bioaccumulation_models_case_study_headerBioaccumulative substances are of concern as they have the potential to biomagnify via the food chain and cause effects on organisms at higher trophic levels.  Bioaccumulation is of particular concern when the substance is toxic as well as persistent or continuously released to the environment.

The current approaches used by the Environment Agency when setting standards for protection of wildlife do not generally take into account possibility of bioaccumulation through the food chain. The Environment Agency therefore commissioned a review to identify models that may be suitable for taking into account bioaccumulation of organic chemicals when setting environmental standards

In 2004 BRE was contracted to carry out the work with RIVM acting as peer reviewers. The project was carried out in several stages.

Firstly, an initial review of 100 models and methods that could be used to predict the bioaccumulation of chemicals was undertaken, covering

  • aquatic food chains,
  • terrestrial food chains, and
  • human food chains.

Thirteen models were then selected for a more in-depth review. A series of objective criteria were developed, taking into account the validity and quality, data requirements, ease of use, transparency, uncertainty and the ability to predict the concentration near the top of the food chain of each of the models. This allowed each model to be ranked in terms of its overall usefulness for use in setting standards.

In the final stage, the two highest ranking models for each of the aquatic food chain, terrestrial food chain and human food chain were validated by comparing predictions obtained from the models with measured data for a wide range of chemicals.

Reliable methods for predicting the bioaccumulation of chemicals are becoming increasingly important in the risk assessment of chemicals. Recent regulatory initiatives have focussed on the identification persistent, bioaccumulative and toxic (PBT) chemicals and the assessment of the effects of these types of chemicals from exposure through the food chain. Reliable methods for prediction of bioaccumulation are vital to such assessments.