title: Time required for blood lead levels to decline in nonchelated children.
abstract: OBJECTIVE
  To determine the time for a decline in blood lead to less than 10 microg/dL in nonchelated children who are enrolled in case management.
  
  
  METHODS
  Retrospective analysis of venous blood lead data of lead-poisoned children followed in a case management program designed to decrease lead exposure. Children were excluded if their blood lead had not yet declined to less than 10 microg/dL, if they received chelation therapy, or if they had not received follow-up for more than 15 months. We calculated the time between peak elevation of lead and decline to less than 10 microg/dL. Data were categorized based on the child's peak blood lead and season in which their peak blood lead occurred. Data were analyzed using ANOVA and linear regression. Kaplan-Meier survival analysis was used to describe data in population form.
  
  
  RESULTS
  579 patients were included in the analysis. Blood leads of 25-29, 20-24, 15-19, and 10-14 microg/dL required 24.0, 20.9, 14.3, and 9.2 months, respectively, to decline to less than 10 microg/dL. For continuous data, a linear relationship was described by the following equation: Time (# of months required to achieve a blood lead less than 10 microg/dL) = 0.845 x peak lead; p < 0.0001. Kaplan-Meier curves complement the findings in a population-based fashion.
  
  
  CONCLUSIONS
  The mean time for blood lead to decline was linearly related to the peak in blood lead. The time for 50% of the blood lead to decline to less than 10 microg/dL was not linear and varied with peak lead.
authors.affiliation: Department of Pediatrics, Medical University of South Carolina, Charleston 29425, USA. Robertsj@musc.edu
authors.forename: J R
authors.initials: JR
authors.lastname: Roberts
authors.forename: J R
authors.initials: JR
authors.lastname: Reigart
authors.forename: M
authors.initials: M
authors.lastname: Ebeling
authors.forename: T C
authors.initials: TC
authors.lastname: Hulsey
mesh_terms: D015913:Chelation Therapy; D002675:Child, Preschool; D004781:Environmental Exposure; D006801:Humans; D007854:Lead / Q000494:pharmacology*; D007855:Lead Poisoning / Q000097:blood* / Q000209:etiology / Q000628:therapy; D008657:Metabolic Clearance Rate; D010150:Paint / Q000009:adverse effects; D012189:Retrospective Studies; D012621:Seasons; D013997:Time Factors
chemical_list: D007854:Lead