Estimating the impact on the food chain of removal of bovine tonsils from specified risk material in Great Britain assuming negligible risk status for bovine spongiform encephalopathy

The earliest estimate for Great Britain (GB) as a whole to achieve negligible risk (NR) status for bovine spongiform encephalopathy (BSE) is 2021. This status allows certain tissues, such as bovine tonsils, to no longer be designated as Specified Risk Materials (SRM). The BSE control model was used to estimate what effect any additional lingual tonsillar material from harvested tongues inadvertently entering the human food chain would have on the amount of infectivity being consumed. Using the baseline model, with tonsils classed as SRM, a mean of 0.08 Bovine Oral (BO) ID50 was estimated to enter the food chain over one year for GB. Under NR status this mean was estimated to increase to 0.83 BO ID50. Whilst this equates to a 10 fold increase in BO ID50 the amount is still small due to the very low likelihood of infected animals being present in the 2017 healthy slaughter population. There are a number of assumptions made within the model, namely, the amount of lingual tonsil inadvertently entering the food chain, and the infectivity titre within this particular tonsillar material.