ZZS-similarity tool Risico's van Stoffen


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Enter the SMILES of a substance to find structural similar ZZS substances.

Model description

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The ZZS structural similarity model is an online tool designed to predict whether a substance looks structurally similar to a ZZS. Structural similarity could be an indication of similar toxicity profiles. Therefore, this model could be used for screening purposes.

The model is based on the methodology as analyzed and evaluated by Wassenaar et al. (2019), with slight variances to facilitate implementation.

Details on the implementation of the methodology, the required input and the interpretation of the output can be found on the ZZS-Similarity tool page.


A SMILES-code of a chemical structure needs to be provided.


Structural similar ZZS are shown for the input structure. The results are categorized into similarity to ZZS with CMR, PBT/vPvB and ED properties. The most similar substance per category is shown on top. Generally, the three most comparable ZZS are shown per category. ZZS that are considered to be structurally similar to the input structure according to the computer model are shown in 'orange'.

It should be noted that the absence of structural similarity to a ZZS does not per definition means no concerns. Vice versa, similarity does not per definition means that a substance exerts a specific effect, it is a trigger for further inspection and analysis.


Simplified Molecular Input Line Entry System
Dutch Substance of Very High Concern (in Dutch: Zeer Zorgwekkende Stoffen)
Carcinogenic, Mutagenic, Reprotoxic
Persistent, Bioaccumulative and Toxic / very Persistent and very Bioaccumulative
Endocrine disruptor