Resolution of a disputed albendazole result in the UK Official Control System highlights need for further guidance?

Scientists in the Government Chemist team within LGC have published the outcome of a technical appeal against the exclusion of a consignment of Brazilian corned beef from the UK food chain. 

When the corned beef was sampled at import the Public Analyst certified against the consignment because of an excess of residues of the veterinary medicine albendazole. Albendazole is a benzimidazole anthelmintic used to destroy parasitic worms in ruminants but residues must not occur above maximum limits in food owing to reported human teratogenicity. A laboratory acting for the importer reported data below the maximum limit, including a finding of the parent drug which is not included in the official definition of the residue. This omission is apparently because albendazole is extensively metabolized and the metabolites are responsible for the systemic biological activity of the medicine.

The Government Chemist was called in to carry out referee analysis and the findings are reported in a paper recently published in the journal Food Additives & Contaminants. Applying liquid chromatography with tandem mass spectrometry, LC-MS/MS, with isotopically labelled internal standards and multiple replication the Public Analysts results were confirmed and the consignment was rejected. Our more extensive analysis of additional samples revealed ‘hot spots’ of albendazole marker residues in the consignment. Full experimental details and the interpretation of the complex law around these issues are given in the paper.

Michael Walker, the lead author, said, “Based on the findings of all the laboratories involved the definition of albendazole residues should be reconsidered to include the parent drug as well as its metabolites. More research and guidance on sampling for veterinary residues are needed to deal with ‘hot spots’ but as a backstop this interesting case shows that appeal to the Government Chemist is a viable and equitable process.”

For more, read "Resolution of a disputed albendazole result in the UK Official Control System – time for more guidance?"