I want to learn to learn how to calculate ADEs myself?

While both the OEL and ADE equations may look straight-forward, the selection of the appropriate point-of-departure (PoD), adjustment factors, and pharmacokinetic (PK) factors can be quite complex, requiring advanced knowledge in toxicology and pharmacology. In addition, as shown below, the EMA’s “Guideline on setting health-based exposure limits for use in risk identification in the manufacture of different medicinal products in shared facilities” states that an “expert review” is required.

This statement was expanded upon in the 2018 EMA Q&A "Questions and answers on implementation of risk-based prevention of cross-contamination in production and ‘Guideline on setting health-based exposure limits for use in risk identification in the manufacture of different medicinal products in shared facilities’ (EMA/CHMP/CVMP/SWP/169430/2012)" where it stated the following:

Then in May 2020, ASTM International published E3219−20 Standard Guide for Derivation of Health-Based Exposure Limits (HBELs) which contained the following statement:

Then finally, in June, 2020, the Pharmaceutical Inspection Convention - Pharmaceutical Inspection Co-Operation Scheme (PIC/s) issued its AIDE-MEMOIRE INSPECTION OF HEALTH BASED EXPOSURE LIMIT (HBEL) ASSESSMENTS AND USE IN QUALITY RISK MANAGEMENT where it stated:

In light of the above requirements, in the MHRA's blog, they posted an article on Cross Contamination Control in Shared Facilities and Equipment. Reflection on common deficiencies and expectations as seen in recent PIC/S guidance. The first item they listed is the following:

Unless you have an advanced degree (M.Sc. or Ph.D.) in a toxicology related field, approximately 5+ years of professional toxicology experience with being mentored by a certified toxicologist, and have published peer-reviewed journal articles in toxicology-related publications, it’s fairly risky to defend yourself as an “expert” in the field. Here at Affygility Solutions we have seen many monographs that have been prepared by "self-taught experts" that deviated significantly from the derived value by an experienced and certified toxicologist. In addition, these "self-taught expert" reports often were poorly researched and documented.