U.S. Department of Agriculture Definition

The U.S. Department of Agriculture's Food Safety and Inspection Service (FSIS) defines Acceptable Daily Intake (ADI) as:

An estimate by the United Nations' Joint Food and Agricultural Organization / World Health Organization Expert Committee on Food Additives (JECFA) of the amount of a veterinary drug, expressed on a body weight basis, that can be ingested daily—by a human—over a lifetime without appreciable health risk (standard man=60 kg).

U.S. Environmental Protection Agency Definitions

The U.S. Environmental Protection Agency defines Acceptable Daily Intake (ADI) in several ways:

• The amount of a chemical a person can be exposed to on a daily basis over an extended period of time (usually a lifetime) without suffering deleterious effects.
• The ADI of a chemical is the estimate of the amount of a substance in food and/or drinking water, expressed on a bodyweight basis, that can be ingested daily over a lifetime without appreciable health risk to the consumer on the basis of all the known facts at the time of the evaluation. It is usually expressed in milligrams of the chemical per kilogram of body weight.
• The estimated amount of a substance that can be consumed every day for a lifetime by humans without presenting a significant risk to their health, based on current scientific evidence.
• Estimated maximum amount of an agent, expressed on a body mass basis, to which an individual in a (sub) population may be exposed daily over its lifetime without appreciable health risk.
• Estimate of the amount of a substance in food or drinking water, expressed on a body mass basis (e.g., mg or ?g/kg body weight), which can be ingested daily over a lifetime by humans without appreciable health risk.
• An estimate of the daily exposure dose that is likely to be without deleterious effect even if continued exposure occurs over a lifetime.
  

U.S. National Library of Medicine Definition

The U.S. National Library of Medicine defines Acceptable Daily Intake (ADI) as an:

Estimate of the amount of a substance in food or drinking water, expressed on a body mass 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. ADI is normally used for food additives (tolerable daily intake is used for contaminants.

Further Reading

• Toxicology Glossary
  
• The Acceptable Daily Intake: A Tool for Ensuring Food Safety.