Abstract: A system for shredding medical waste, the system comprising a medical waste treating chamber (4) being an interior of an enclosure disposed within an environment which is not to be polluted, a motor (11a), a shredder (2) seated in the chamber and including a motor-driven shaft (17) and blades rotated by the shaft, the shaft (17) extending through the enclosure thereby to define an interface between the waste treating chamber (4) and the environment, and interface seal apparatus (101) preventing leakage of at least fluids from the medical waste treating chamber into the environment, via the interface.