A middle aged man from West Bengal presents with paraesthesia of hands and feet, hyperkeratosis of palms, lines on his nails and rain drop pigmentation. The most likely causative toxin for the above mentioned presentation is:

Paraesthesia of hands and feet, hyperkeratosis of palms, lines on nails and rain drop pigmentation is characteristic of arsenic poisoning. Ref: The Essentials of Forensic Medicine and Toxicology By Dr K S Narayan Reddy, 27th Edition, Pages 473-75; Environmental and Chemical Toxins and Psychiatric Illness By James S Brown, Page 117; Parikh's Textbook of Medical Jurisprudence and Toxicology, 6th Edition, Pages 9.8-9.12