The relevant framing is that risk here comes from three separate places: what the material is, how it is handled, and what it does. They need three different mitigations.
Know the symptoms that end the discussion: severe epigastric pain radiating to the back, persistent vomiting with reduced urine output, spreading redness with fever, jaundice, chest pain or breathlessness.
Have a plan for stopping before you start, including what you would do with the remaining material and how you would tell someone what you had taken.
The symptom patterns listed above correspond to recognised emergencies with defined presentations, which is why recognition rather than management is the useful skill.
Keep a written log with lot numbers. It is what a professional can actually use.