title: Continual Decrease in Blood Lead Level in Americans: United States National Health Nutrition and Examination Survey 1999-2014.
abstract: BACKGROUND
  Lead is toxic and affects neurodevelopment in children even at low levels. There has been a long-term effort in the United States to reduce exposure to lead in the environment. We studied the latest US population blood lead levels and analyzed its trend.
  
  
  METHODS
  Blood lead levels in 63,890 participants of the National Health Nutrition and Examination Survey 1999-2014 were analyzed using SPSS Complex Samples v22.0 (IBM Corp, Armonk, NY).
  
  
  RESULTS
  Mean blood lead levels and 95% confidence intervals (CIs) were 1.65 μg/dL (1.62-1.68), 1.44 μg/dL (1.42-1.47), 1.43 μg/dL (1.40-1.45), 1.29 μg/dL (1.27-1.32), 1.27 μg/dL (1.25-1.29), 1.12 μg/dL (1.10-1.14), 0.97 μg/dL (0.95-0.99), and 0.84 μg/dL (0.82-0.86) in 1999-2000, 2001-2002, 2003-2004, 2005-2006, 2007-2008, 2009-2010, 2011-2012, and 2013-2014, respectively. Blood lead levels decreased significantly (P <.001), and the trend remained significant when stratified by age, gender, ethnicity, and pregnancy status (P <.05). Estimated percentages of children with blood lead level ≥5 μg/dL were 9.9% (95% CI, 7.5-12.9), 7.4% (95% CI, 5.9-9.4), 5.3% (95% CI, 4.1-6.9), 2.9% (95% CI, 2.1-3.9), 3.1% (95% CI, 2.0-4.8), 2.1% (95% CI, 1.5-3.1), 2.0% (95% CI, 1.0-3.6), and 0.5% (95% CI, 0.3-1.0) in 1999-2000, 2001-2002, 2003-2004, 2005-2006, 2007-2008, 2009-2010, 2011-2012, and 2013-2014, respectively. The decreasing trend was significant (P <.05). In children aged 1 to 5 years in the National Health Nutrition and Examination Survey 2011-2014, the estimated 97.5 percentile of blood lead level was 3.48 μg/dL.
  
  
  CONCLUSIONS
  Blood lead levels have been decreasing in the US population. The reference level also should decrease. It is still important to monitor blood lead levels in the population, especially among pregnant women and children aged 1 to 5 years.
authors.affiliation: Division of Clinical Pharmacology and Therapeutics, Department of Medicine, The University of Hong Kong, Pokfulam, China.
authors.forename: Man-Fung
authors.initials: MF
authors.lastname: Tsoi
authors.affiliation: Division of Clinical Pharmacology and Therapeutics, Department of Medicine, The University of Hong Kong, Pokfulam, China; Research Centre of Heart, Brain, Hormone and Healthy Aging, The University of Hong Kong, Pokfulam, China; Partner State Key Laboratory of Pharmaceutical Biotechnology, The University of Hong Kong, Pokfulam, China; Department of Pharmacology and Pharmacy, The University of Hong Kong, Pokfulam, China.
authors.forename: Ching-Lung
authors.initials: CL
authors.lastname: Cheung
authors.affiliation: Division of Clinical Pharmacology and Therapeutics, Department of Medicine, The University of Hong Kong, Pokfulam, China; Research Centre of Heart, Brain, Hormone and Healthy Aging, The University of Hong Kong, Pokfulam, China.
authors.forename: Tommy Tsang
authors.initials: TT
authors.lastname: Cheung
authors.affiliation: Division of Clinical Pharmacology and Therapeutics, Department of Medicine, The University of Hong Kong, Pokfulam, China; Research Centre of Heart, Brain, Hormone and Healthy Aging, The University of Hong Kong, Pokfulam, China; Partner State Key Laboratory of Pharmaceutical Biotechnology, The University of Hong Kong, Pokfulam, China; Institute of Cardiovascular Science and Medicine, The University of Hong Kong, Pokfulam, China. Electronic address: mycheung@hku.hk.
authors.forename: Bernard Man Yung
authors.initials: BM
authors.lastname: Cheung
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D004781:Environmental Exposure; D005260:Female; D006801:Humans; D007223:Infant; D007854:Lead / Q000097:blood*; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D011158:Population Growth; D011247:Pregnancy; D014481:United States; D055815:Young Adult
chemical_list: D007854:Lead
keywords: Blood lead level; NHANES