Safety of _L-tryptophan produced by fermentation with Escherichia coli CGMCC 7.59 for all animal species based on a dossier submitted by Feedway Europe NV

L-Tryptophan is a feed additive produced by fermentation using a genetically modified strain of Escherichia coli. The EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP Panel) issued an opinion on the safety and efficacy of the product, which concluded that ‘The use of L-tryptophan produced by E. coli CGMCC 7.59 in feed is safe for non-ruminant target species when supplemented to diets in appropriate amounts. As the metabolites of L-tryptophan produced by ruminal bacteria may be toxic to the host animal, oral administration of unprotected L-tryptophan to ruminants should be avoided. The Panel on Additives and Products or substances used in Animal Feed (FEEDAP) has concerns about the safety of L-tryptophan for target species when administered via water for drinking. . . . . .In the absence of any data on sensitisation, the product should be considered a potential dermal sensitiser. The level of endotoxins present in the product and its dusting potential indicate a health risk for the user upon inhalation’. The European Commission asked EFSA to deliver an opinion on the safety of L-tryptophan, produced by an improved manufacturing process, as a nutritional additive for all animal species based on additional data submitted by the applicant on characterisation of the additive. The FEEDAP Panel reiterates its concern on the use of unprotected tryptophan to ruminants and on the safety of the amino acid L-tryptophan for target species when administered simultaneously via water for drinking. As the estimated maximum exposure to endotoxins by inhalation of the improved product is below the provisional occupational exposure limit, no risk from exposure to endotoxins for people handling the additive is expected. Concerns remain about possible dermal sensitisation.