Brain, spinal cord and associated nerves form the central nervous system tissues, and in meat safety they carry a special status. Prions causing BSE concentrate in these tissues, so many countries list them as specified risk materials banned from the human food chain. Slaughterhouses must remove, dye and dispose of them under veterinary supervision, with records proving compliance. Born of the BSE crisis, these controls still anchor beef safety, and routine brain testing of cattle continues as a precaution. Rendering plants handle this material under strict rules, keeping it entirely out of animal feed.