Preliminary results from research sponsored by the UK’s Food Standards Agency have, for the first time, found BSE infectivity in cow tonsil.
Current controls require all cow tonsil to be removed from meat intended for human consumption.
The new tests, which the Agency said are considered to be several hundred-fold more sensitive than those previously applied using mice, involve the injection of a range of tissues from infected cattle into BSE-free cows to determine if they carry infectivity.
One out of five cows has gone down with BSE, 45 months after they were injected with tonsil tissue samples collected from the infected cattle.
The long incubation period indicates that the level of infectivity in tonsil is relatively low. Tonsil tissue from cattle previously tested using mice has not been shown to carry infectivity.
However as a precautionary measure, EU wide legislation classifies bovine tonsil over a certain age as specified risk material (SRM). It is banned from the food chain in the UK and Portugal from cattle over six months of age, and from cattle over 12 months of age in other EU countries, the Agency said.
The same SRM rules require tonsil to be stained with a dye and destroyed once removed. Under separate EU wide hygiene regulations, tonsil from cattle of any age cannot enter the food chain.
Controls on bovine offal, including tonsil, were first introduced in England and Wales in 1989. It is known that tonsil tissue can be found at the root of the tongue. A limited initial study of current practice has already indicated that tonsil tissue does not appear to remain on tongues prepared for human consumption. Tongue is not SRM and can enter the food chain.
The Agency plans to assess the way in which tongue is extracted, in particular to see whether any traces of tonsil tissue might be inadvertently included with tongue. The results from these further investigations into the way bovine tongues are removed will form part of a risk assessment to be considered by the Government’s BSE advisory committee, SEAC (Spongiform Encephalopathy Advisory Committee). Decisions on whether any further precautionary action might be required will be taken following that assessment.