Acceptable Daily Intake which is abbreviated ADI refers to the amount of chemicals, whether a drug or additive (in food or drinking water) which if ingested daily over a lifetime would not produce any appreciable health risk.
It is expressed on a basis (usually mg/kg body weight), which can be ingested daily over a lifetime by humans without appreciable health risk. For calculation of the daily intake per person, a standard body mass of 60 kg is used. The acceptable daily intake is normally used for food additives (tolerable daily intake is used for contaminants).
The higher the ADI, the 'safer' a compound is for regular ingestion.