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Decreasing Blood Lead Levels in Americans

Am J Med; 2016 Nov; Tsoi, Cheung, et al

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While lead levels have been decreasing in the US population, it is important to continue to monitor blood lead levels, especially among pregnant women and children aged 1 to 5 years, a recent study found. Blood lead levels were analyzed in 63,890 participants of the National Health Nutrition and Examination Survey (NHANES) from 1999 to 2014. Researchers found:

• Mean blood levels were 1.65 μg/dL, 1.44 μg/dL, 1.43 μg/dL, 1.29 μg/dL, 1.27 μg/dL, 1.12 μg/dL, 0.97 μg/dL, and 0.84 μg/dL in 1999-2000, 2001-2002, 2003-2004, 2005-2006, 2007-2008, 2009-2010, 2011-2012, and 2013-2014, respectively.

• Blood lead levels decreased significantly and the trend remained significant when stratified by age, gender, ethnicity, and pregnancy status.

• Estimated percentages of children with blood lead level ≥5 μg/dL decreased during the study period and was significant.

• In children aged 1 to 5 years in the NHANES 2011-2014, the estimated 97.5 percentile of blood lead level was 3.48 μg/dL.

Citation: Tsoi MF, Cheung CL, Cheung TT, Cheung BMY. Continual decrease in blood lead level in Americans: United States National Health Nutrition and Examination Survey 1999-2014. Am J Med. 2016;129(11):1213-1218. doi:10.1016/j.amjmed.2016.05.042.

Commentary: There is no safe amount of lead in blood as even low blood lead levels (BLL) have been demonstrated to have adverse pediatric consequences, including IQ deficits, attention-related behaviors, and poor academic achievement, as well as adverse cardiovascular, immunological, and endocrine effects. This has led the CDC to change the upper acceptable limit of lead from the previous 10 ug/dL to a lower, epidemiologic-based upper limit based on the 97.5th percentile of the BLL levels among children aged 1 to 5 in the US (currently 5 μg/dL). Using that value, approximately 450,000 children in the US have BLLs higher than the upper limit.1 If blood levels are above 10 ug/dL, then close follow-up, environmental lead elimination and repeat testing is necessary; if they are above 45 ug/dL, then chelation may be indicated.2 While the current study shows that lead levels are decreasing across the US, the unfortunate events in Flint, MI, where the rate of elevated blood levels in children under 5 years old more than doubled after the water source was changed from Detroit to the Flint River, remind us that health risks are often local as well.3 —Neil Skolnik, MD

1. Centers for Disease Control and Prevention. CDC response to advisory committee on childhood lead poisoning prevention. June 7, 2012. https://www.cdc.gov/nceh/lead/acclpp/cdc_response_lead_exposure_recs.pdf. Accessed November 4, 2016.

2. California Department of Public Health. Management guidelines on childhood lead poisoning for health care providers. https://www.cdph.ca.gov/programs/CLPPB/Documents/Provider%20mgmt%20guides.pdf. Accessed November 4, 2016.

3. Hanna-Attisha M, LaChance J, Sadler RC, Schnepp AC. Elevated blood lead levels in children associated with the Flint drinking water crisis: A spatial analysis of risk and public health response. American Journal of Public Health. 2016;106(2):283-290. doi:10.2105/AJPH.2015.303003.

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