Screening-level BCF and BAF models

This model provides screening-level estimates of the bioaccumulation factor (BAF) for generic fish species in lower, middle and upper trophic levels of aquatic food webs. The model also provides screening-level estimates of the bioconcentration factor (BCF) for water exposures only (i.e., in laboratory bioconcentration tests). The models require only the octanol-water partition coefficient (KOW) of the chemical and the metabolic biotransformation rate constant as input parameters (see database and the BCFBAF module of U. S. EPA’s EPI Suite™).

The BAF models are derived from the parameterization and calibration of a mechanistic bioaccumulation model to a large database of evaluated measured BAFs. The measured BAFs are for chemicals that are poorly metabolized and are grouped into lower, middle and upper trophic levels of fish species. The model is calibrated to each trophic level of measured BAF values thus providing estimates that are in general agreement with measured BAFs, thus capturing the overall food web biomagnification potential of chemicals in aquatic food webs for screening assessments.

The model is intended to estimate BCFs and BAFs for non-ionic organic chemicals only. Thus it provides generic estimates in absence of site-specific measurements or estimates. The model can be used to predict dietary concentrations for higher trophic level predators (e.g., birds and mammals) including human exposure concentrations from fish in their diet. A previous version of the model has been used to categorize chemicals for their potential to bioaccumulate in aquatic food webs for Environment Canada to address legislation outlined under the Canadian Environmental Protection Act 1999. The model is coded in a Microsoft Excel™ workbook.

General information on the model is available in the following publication:

– Arnot JA, Gobas FAPC. 2003. A generic QSAR for assessing the bioaccumulation potential of organic chemicals in aquatic food webs. QSAR Comb Sci 22(3): 337-345.

Versions for Download:

BCFBAF Ver1.2 model (Spreadsheet Model)

OR available in U. S. EPA’s EPI Suite

BCFBAF Download Registration Form