The ISO 19838 "Guidelines for the application of ISO standards in the field of microbiology of cosmetic products" provides explanations on how the individual ISO standards in the field of microbiology of cosmetic products are to be applied and how they interrelate.

The standard also includes some case examples for the practical evaluation of results from microbiological examinations

• the evaluation criteria of the preservation challenge test according to ISO 11930
• examples for evaluating the results of the preservation challenge test
• decision tree for assessing the microbial content of a cosmetic product
• decision tree for interpreting microbiological results
• examples for assessing microbiological results of various products