Which of the following is the earliest sign of lead poisoning?

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.