I have 5 evaluation criteria for worst case determination : solubility, toxicity, amount and type of of every ingredient (if it is actif or excipient) and finally the cleanability of finish product.
For every ingredient and every criteria i assign rating numbers. And addition of all rating number give the score of the product. This procedure is done for every products and the product with high score is selected as worst case. That is why if there is more ingredients, the score of the product is greater.
I don’t know if this is a scientific rating strategy . if i’m not right, please tell me what is your rating procedure or strategy.