KREATiS tutorials - experimentation VS. QSAR model
Kreatis replacing experimentation for reach - REACH alternative laboratory testing
Kreatis - an alternative to experimentation for REACH - REACH alternative experimentation


The problem with experimentation

Years ago it was recognised that regulatory studies had to be normalised to prevent inappropriate measurements from being made and to provide a basis for scientific methodology allowing results from different substances to be compared. International Chemical testing Guidelines (e.g. ISO, OECD) were created for this purpose but every substance has its own set of properties and all potential issues cannot be covered in just a few pages.

An introduction to QSAR

The term "QSAR" stands for Quantitative Structure-Activity Relationship.
QSARs are based on the principle that similar chemical structures can lead to similar biological activities. QSAR is often replaced by the term "QSPR" (Quantitative Structure-Property Relationship).

What are HA-QSARs ?

Often, the ultimate objective of the QSAR model is to prioritise chemicals for further testing rather than to predict an exact experimental value [...]. For this reason, it seems necessary to distinguish between QSARs created to provide approximations of experimental values and those specially designed to substitute for specific experimental endpoints, the HA-QSARs.

New Mechanism of Action definitions based on Molecular Initiating Events and a classification algorithm based on calculated stru

New MechoAs definitions and a corresponding classification algorithm.
We have developed this to replace Verhaar's scheme and its limitations (ambiguous categories, restricted Applicability Domain) with an improved classification. This classification scheme for Mechanisms of Action (MechoAs) is required to be sure to use appropriate QSAR models when one wants to predict (eco)toxicity.

iSafeRat® WAF calculation method to determine aquatic toxicity of mixtures (15 min)

Introduction of the iSafeRat® 3-step calculation method using to determine aquatic toxicity of mixtures:

a) First, actual concentration of each constituent in the aqueous phase, called also AMAP (Analytically Measurable Aqueous Phase) is calculated from a given original mixture composition thanks to a thermodynamic algorithm;
b) Next, the non-bioavailable phase was accounted for and excluded from the aqueous phase;
c) Finally, the new algorithms from the ecotoxicity QSAR were used as above to determine the relative toxicity of each constituent in terms of activity to get the global activity of the mixture, and so its toxicity

This page is dedicated to those who are aware of QSARs and know that REACH allows them to be included in REACH dossiers but lack the confidence to use them.

The tutorials on this page will explain the basic principles of how QSARs work and model development, explain why mechanistic interpretation is so important, how methods for building QSARs can differ and discuss available QSAR models, their accuracy and validity.

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KREATiS, Knowledge & research in environment and toxicology in silico

Knowledge & research in environment and toxicology in silico