**6. Mechanisms underlying neurodegenerative diseases**

The main neurotoxic consequences of ACR are peripheral nervous system (PNS) degradation and degeneration in a brain area related to learning and memory function. Drowsiness, cerebellar ataxia, muscle atrophy, dysarthria, and sensory or motor peripheral polyneuropathy are common clinical symptoms [56, 57]. ACR-induced neurotoxicity is associated with symptoms like ataxia, hindfoot splay, skeletal muscle weakness, and numbness of the hands and feet [1, 58]. ACR-induced neurodegenerative diseases have been shown in various studies to be mediated by axon and medullary sheath destruction in the PNS [59]. Distal axon swelling and degeneration are the key pathological features of ACR exposure [56, 60]. Even though recent research studies report that ACR-induced neurotoxicity and neurodegenerative effects in humans and experimental animals are mediated by nerve terminal and axonal damage, the exact underlying mechanism remains unclear [58].
