No level of lead in a child's blood has been identified as safe, and even low blood lead levels can cause life-long health problems. Yet it can be difficult for blood sampling methods and equipment to accurately measure small amounts of lead in blood, according to a study published in the August 2017 Pediatrics. The study, "Measurement Challenges at Low Blood Lead Levels," (published online July 17) observes that the U.S. Centers for Disease Control and Prevention's reference value remains at or above 5 micrograms of lead per deciliter of blood (5 ug/dL). A CDC committee set that reference value in 2012 based on the estimate of U.S. children ages 1-5 who were in the top 2.5 percent of the population for blood lead levels. As blood lead levels in U.S. children have declined, the level above which includes top 2.5 percent of children is 3.48 micrograms per deciliter of blood, according to more recent data provided by the National Health and Nutrition Examination Survey, the study states. The children identified with levels above that value were more likely to be younger than 3 years old and living in low-income households. The authors detail the challenges in obtaining accurate and precise measurements for blood lead levels at or below 5 ug/dL. In addition, the CDC Pediatrics article reported that 35 percent of devices used for the 2015-16 blood lead level measurements were contaminated by external sources of lead, raising the question of whether small changes are real or indicate measurement variability. CDC outlines steps laboratories, clinicians, and manufactures can consider to achieve precise and accurate blood lead measurements with lower level of detections (LOD) in the article.
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