The amount of a food additive, pesticide residue or veterinary drug residue that can be ingested every day over a lifetime without appreciable health risk, expressed per kilogram of body weight. Expert bodies such as JECFA derive it from long-term toxicology studies, dividing the no-effect dose by safety factors — typically one hundred — to protect sensitive individuals. The ADI is the bridge between laboratory toxicology and practical food law: it underpins maximum residue limits, permitted additive levels and the safety evaluation of flavourings and processing aids. Staying beneath the ADI is the central goal of dietary exposure assessment.