Continual Decrease in Blood Lead Level in Americans: United States National Health Nutrition and Examination Survey 1999-2014

Abstract

BackgroundLead 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. MethodBlood 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). ResultsMean 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. ConclusionsBlood 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.