The Bioaccumulation Assessment Tool (BAT)

The downloadable materials included on this website are provided to interested parties at no cost; however, to download any material you need to register by completing a form with your name, e-mail address and affiliation. The registration information provides us with contact information so that we can send notifications for model updates. The models are updated occasionally to address potential errors and “bugs in the code” and to reflect scientific advancements.

For more information about these models, tools and databases please contact Jon Arnot.

The Bioaccumulation Assessment Tool (BAT)

Chemicals are being assessed for bioaccumulation (B) potential using various lines of evidence, methods, metrics and classification criteria.  In vivo laboratory-based lines of evidence include the bioconcentration factor (BCF) and biomagnification factor (BMF).  In vitro biotransformation rate data (S9, hepatocytes) can also be applied for “B” assessment using in vitro-in vivo extrapolation (IVIVE) methods.  Field-based lines of evidence include the BMF, bioaccumulation factor (BAF), and the Trophic Magnification Factor (TMF). In silico lines of evidence include quantitative structure-activity relationships (QSARs) for the BCF and the biotransformation rate constant and mass balance bioaccumulation (toxicokinetic) models.

The Bioaccumulation Assessment Tool (BAT) was developed to guide the collection, generation, evaluation, and integration of various lines of evidence to aid bioaccumulation assessment decision-making for aquatic and terrestrial organisms.  The BAT facilitates the systematic and transparent integration of information in a consistent framework to inform bioaccumulation assessment decision-making by providing a Weight of Evidence (WOE) approach that includes critical evaluations of data confidence (quality). The BAT WOE approach is aligned with the Guiding Principles and Key Elements for Establishing a Weight of Evidence for Chemical Assessment provided by the Organization for Economic Coordination and Development (OECD).

The BAT was developed with stakeholder involvement including representatives from academia, government and industry with research support from Cefic LRI and the ACC LRI The BAT is implemented (coded) in Visual Basic for Applications (VBA) and the Graphical User Interface is designed in Excel™. BAT Ver.1.0 was released October 2018. BAT Ver.1.01 was released September 2019, BAT Ver2.0 was released May 2021 and BAT Ver.2.02 was released September 2021. The BAT is free and downloadable using the registration and links provided below.  The BAT User Manual and Quick Start Guide are embedded as pdfs within the Excel file.

This Quick Start Guide can be considered to expedite the use of the BAT; however,
all BAT users are strongly encouraged to read the User Manual before using the BAT.


We have made some minor, but important, updates to BAT Ver.2.0. The BAT Ver.2.02 is available for free download at the link below. BAT Ver.2.02 includes several new features:
  • Lines of Evidence (LoE) are now only included in the Strength of Evidence (SoE) summary table, 
    IF the LoE has a reliability score (RS) > 0. For transparency, all LoE data are still displayed in the Summary Results Sheet.
  • Updated default parameters for the built-in BAT model calculations lab B-metrics for aquatic species to reflect median values from experimental bioaccumulation testing databases.
  • Addition of user-defined weighting of biotransformation study types to the Chemical Summary Sheet for parameterizing the built-in BAT model. Defaults are provided if the user does not choose their own values.
  • Addition of a user-defined option for scaling fish biotransformation rate constants to invertebrate biotransformation rate constants to parameterize the built-in BAT models.
  • Addition of a user-selected option for choosing whether to use growth corrected B metrics from lab studies in the 
    Weight of Evidence (WoE).
  • BAT Bug Fixes / Corrections:
  • – Error in field bioaccumulation factor (BAFSS) calculation.
    – Error in steady-state and kinetic lab B-metric calculation output provided by the built-in BAT models; output are now consistent.
    – Total elimination half-life (HLT) output erroneously appeared in units of hours, but it was labelled days; output units now corrected to days.

How to Cite BAT Ver 2.02:

– Armitage JM, Toose L, Embry M, Foster KL, Hughes L, Sangion A, Arnot JA. 2021. The Bioaccumulation Assessment Tool (BAT) Version 2.02. Developed by ARC Arnot Research and Consulting Inc., Toronto, ON, Canada

How to download the BAT

How to open and initialize the BAT for a chemical of interest

How to enter physical-chemical properties for a neutral organic chemical into the BAT

How to enter empirical or user-preferred chemical dietary absorption efficiency studies for fish and mammals into the BAT

How to enter in vivo biotransformation half-life studies

Limitations of liability and disclaimer of warranty
ARC Arnot Research & Consulting Inc. and all associated collaborators do not guarantee, warrant, or make any representations, either expressed or implied, regarding the use, or the results of the use of the materials provided with regards to reliability, accuracy, correctness, or otherwise. There are no warranty rights granted to users of the models or databases provided.

Users assume the entire risk as to the results and performance of the models and databases. ARC Arnot Research & Consulting Inc. and all associated collaborators are not liable under any circumstances, for any damages whatsoever, arising out of the use, or the inability to use, the models and databases provided, even if advised of the possibility of such damages.