Clinical Effects
    

 Children with blood lead concentrations greater than 60 /dL may complain of headaches, abdominal pain, loss of appetite, and constipation and display clumsiness, agitation, and/or decreased activity and somnolence. These are premonitory symptoms of CNS involvement and may rapidly proceed to vomiting, stupor, and convulsions.³⁴ Symptomatic lead toxicity should be treated as an emergency. Although lead can cause clinically important colic, peripheral neuropathy, and chronic renal disease in adults with occupational exposures, these symptoms are rare in children（420 American Academy of Pediatrics Committee on Environmental Health. 2005; ）   

The gastrointestinal and central nervous systems yield symptoms, but fewer than 5% of children are diagnosed as having lead poisoning based on clinical presentation. Gastrointestinal-related symptoms include anorexia, nausea, vomiting, abdominal pain, and constipation. The combination of recurrent or intermittent abdominal pain, vomiting, and constipation should raise the suspicion of lead poisoning. The BLL threshold for gastrointestinal symptoms has been stated to be approximately 2.4 mcmol/L (50 mcg/dL). However, a recent preliminary report suggests that symptoms may be present in nearly 50% of children who have BLLs of 0.97 to 2.2 mcmol (20 to 45 mcg/dL). Lead poisoning was a lethal disease in the United States and continues to contribute to mortality in developing countries. At levels above 4.83 mcmol/L (100 mcg/dL), some children may show evidence of encephalopathy, including a marked change in mentation or activity, ataxia, seizures, and coma. Physical examination may yield evidence of increased intracranial pressure. Since the advent of lead screening and restrictions in lead usage, lead-related deaths have become extremely rare. Sequelae in survivors include retardation, palsies, and growth failure（424 Markowitz,M. 2000; ）