When comparing the distribution of the wrongly categorized chemicals, we observed a higher levels of homogeneity in the k-means categories compared to the GHS ones. This was consistent for both QSAR regression model and direct classification model. We also observed that for the GHS categories, both the QSAR regression-based and the direct classification model showed a high density of wrong categorization for chemicals at the border between high toxicity and moderate toxicity region. We interpret that this is mainly caused by larger number of categories and lower levels of rigidity in the k-means approach compared to hard set thresholds (i.e. GHS approach).