Report of workshop on the significance of excursions of intake above the ADI

The acceptable daily intake (ADI) for humans was originally developed by th e Joint FAO/WHO Expert Committee on Food Additives (JECFA) and defined as " an estimate of the amount of a food additive, expressed on a body weight ba sis, that can be ingested daily over a lifetime without appreciable health risk." JECFA has not provided any firm guidance on how to evaluate excursio ns of intake above the ADI, but WHO in 1987 stated that "because in most ca ses, data are extrapolated from life-time animal studies, the ADI relates t o life-time use and provides a margin of safety large enough for toxicologi sts not to be particularly concerned about shortterm use at exposure levels exceeding the ADI, providing the average intake over longer periods of tim e does not exceed it." In discussing short-term intakes in excess of recomm ended limits, JECFA in 1989 concluded that short-term exposures to levels e xceeding the provisional tolerable weekly intake (PTWI) for a contaminant i s not a cause of concern, provided the individual's intake averaged over lo nger periods of time does not exceed the level set. JECFA also stated that it was impossible to make a generalization concerning the length of time. d uring which intakes in excess of the PTWI would be toxicologically detrimen tal, Any detrimental effect would depend upon the nature of the toxicity an d the biological half-life of the chemical concerned. JECFA considered inta kes of food additives in excess of the ADI less Likely to occur and easier to control than in the case of contaminants which are allocated either a PT WI or a tolerable daily intake (TDI). The ILSI Europe Acceptable Daily Inta ke Task Force together with the Food Chemical Intake Task Force initiated a workshop which took place April 21-23, 1998, in Milan, Italy, in order to help identify what information would be needed, with what precision, and wh at is already available to evaluate the significance of excursions of intak e above the ADI, The specific aims of the workshop were to address the foll owing questions: By how much can the ADI be exceeded? For how long can excursions above the ADI be tolerated with respect to chro nic toxicity, accumulation, and mechanisms of toxicity? What method should be used to estimate intakes so that the estimates are re levant to the ADI? Do the same principles apply to contaminants that have TDI or PTWI values?