This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Forensic Medicine
[{'content': 'Which of the following is the earliest sign of lead poisoning? \nSelect and explain. \nA. Facial pallor, B. Colic and constipation, C. Punctate basophilia, D. Encephalopathy', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Facial pallor paicularly of the mouth is the earliest and most consistent sign of chronic lead poisoning and is due to vasospasm. Chronic poisoning results from a daily intake of 1-2mg of lead. Other characteristic features of chronic lead poisoning are anaemia (punctate basophilia), lead line, colic and constipation, lead palsy and encephalopathy. Reference: Essentials of Forensic Medicine and Toxicology by Dr K.S Narayan Reddy 27th edition page 479.', 'role': 'assistant'}]