PDE Value Calculation

What we can use LD50 value to calculate NOEL which to be used for determine PDE value in below formala:

PDE = NOEL x Weight adjustment / F1xF2xF3xF4xF5

If we not having clinical or nonclinical toxicology data… to calculate MACO as per EMEA guideline…??

Anybody can answer please by spending your valuable time please…

I awaiting for reply…

I am awaiting for reply… Please…