Tolerable weekly intake (TWI) estimates the amount per unit body weight of a potentially harmful substance or contaminant in food or water that can be ingested over a lifetime without risk of adverse health effects.
[3] The term TWI should be reserved for when there is a well-established and internationally accepted tolerance, backed by sound and uncontested data.
[4] The concept of TWI takes into account daily variations in human consumption patterns.
Governments and international organizations such as the Joint FAO/WHO Expert Committee on Food Additives (JECFA), the Joint FAO/WHO Meeting on Pesticide Residues (JMPR), the World Health Organization (WHO) and the Food and Agriculture Organization of the United Nations (FAO) generally use the safety factor approach, based on ADI, to determine intake tolerances for substances that exhibit thresholds for toxicity.
[3] The Codex Alimentarius Commission, with the help of independent international risk assessment bodies or ad-hoc consultations organized by FAO and WHO, develops and publishes tolerances based on the best available science.