EFSA Panel on Biological Hazards (BIOHAZ); Scientific Opinion on On-site treatment of pig carcasses

EFSA’s Scientific Panel on Biological Hazards (BIOHAZ) was asked for a scientific opinion on an alternative method for processing Category (Cat) 2 Animal By-Products (ABP). The materials to be treated are placentas and fallen pigs; this implies that the animals died due to a disease, which in most cases was not properly diagnosed.

The target parameters are: i) particle size less than 150 mm and ii) heating for 10 – 12 hours at 100°C. The end-product obtained is mixed with pig slurry and used as an organic fertiliser. According to the legislation in force, before being used as an organic fertiliser, Cat. 2 material should be treated with a sterilisation process (i.e. 133°C / 20 min / 3 bars / 50 mm particle size).

The most resistant hazards identified by the applicant as target to demonstrate the risk reduction are spores of pathogenic clostridia. Due to uncertainty on the cause of the animals’ death, the presence of more resistant hazards cannot be considered negligible. The sterilisation process defined in the current legislation is able to minimise the risks due to unidentified agents, such as Bacillus anthracis and TSE agents.

The BIOHAZ Panel concluded that the process proposed was not properly validated experimentally under real scale conditions. In theory, it should permit a high degree of reduction of spores of pathogenic clostridia but because of several uncertainties (i.e. water evaporation, fat protective effect and particle size) it is not certain that the values of the parameters used in the theoretical calculations would apply in practice.

Moreover, the proposed alternative method cannot be considered equivalent to the sterilisation process defined in the current legislation. This would be particularly relevant in the case of extremely heat resistant spores being present in the material to be treated.