<prompt> A middle aged man presents with paraesthesia of hands and feet. Examination reveals presence of Mees lines in the nails and rain drop type pigmentation in the hands. The most likely causative toxin for the above mentioned symptoms is:LeadArsenicThalliumMercury  <response>: CNS symptoms along with Aldrich-Mees lines in the nails and rain drop type pigmentation in the hands suggests this case as chronic Arsenic poisoning. Ref: The Essentials of Forensic Medicine and Toxicology By K S Narayan Reddy, 27th Edition, Pages 473,475,476,478,482 