INTERNATIONAL PROGRAMME ON CHEMICAL SAFETY
WORLD HEALTH ORGANIZATION
Toxicological evaluation of certain veterinary drug
residues in food
WHO FOOD ADDITIVES SERIES 39
The forty-eighth meeting of the Joint FAO/WHO Expert
Committee on Food Additives (JECFA)
World Health Organization, Geneva 1997
The Committee examined the results of studies of antimicrobial
activity in vitro in which relevant gut microflora were used to
calculate ADIs for some of the antimicrobial agents that were
reviewed. The equation used for deriving the ADIs is based on that
shown in Annex 5 of the report of the thirty-eighth meeting of the
Committee (Annex 1, reference 97). The equation was modified at the
forty-seventh meeting (Annex 1, reference 125), and the modified
version was used to derive ADIs based on microbiological activity at
the present meeting.
The upper limit of the ADI was derived as follows:
Upper limit MIC50 (µg/g) × MCC (g)
of ADI =
(µg/kg bw) FA × SF × BW (kg)
MIC50 = The minimum concentration of an antimicrobial drug that
completely inhibits the growth of 50% of cultures of a
given microorganism, as judged by the naked eye, after
a given period of incubation. For the purposes of the
evaluation, the MIC50 value is the mean MIC50
value(s) for the strain(s) of the relevant species
tested. Alternatively, the lowest MIC50 value for the
most sensitive species can be used.
MCC = Mass of colonic content; a value of 220 g is used.
FA = Fraction of an oral dose available to act upon
microorganisms in the colon
SF = The safety factor used to account for uncertainty about
the amount and relevance of data for MIC values
available for review; may range from 1 to 10, a value
of 1 being used when extensive, relevant
microbiological data are available.
BW = Body weight; a value of 60 kg is used.