Very soon, the Centers for Disease Control and Prevention “reference level” for blood lead concentration will be lowered from 5 μg/dL to 3.5 μg/dL. As Charles Schmidt explains in his superb well-researched article “America’s Misguided War on Childhood Lead Exposures” just published by Undark Magazine, there are several crucially important things to realize about this change:
- This impending lowering of the reference lead level is the latest in a long series. The reference level was 40 μg/dL until it was lowered to 10 μg/dL in 1999. The last decree was to 5 μg/dL in 2012.
- The reference level is not really a clinical standard or predictor of significant lead toxicity. It is mean to indicate that the child should enter a lead case management program involving, among other things, analysis of the child’s home environment and institution of abatement measures as needed.
- At this point the “reference level” is determined by statistics, not clinical evidence. Every 4 years population data is reevaluated, and the level readjusted to the point where 97.5% of children have lead levels below the standard. (Note that a corollary of this procedure is that the more successful we are at lowering lead levels in the population, the lower the reference level will go. At all times, 2.5% of children will be deemed in need of case management. This is truly a toxicological protocol worthy of Sisyphus.)
- The lowering of the reference lead level to 3.5 μg/dL will make hundreds of thousands additional children eligible for case management in a system that is already overburdened and under-resourced, without any proof that this change would result in improved health or do anything except alarm families.
- Dr. Kim Dietrich — the only person on the CDC’s 16-member expert panel to vote against lowering the reference level — claims in the article that most labs can not accurately measure lead levels as low as 3.5 μg/dL.
- Many pediatricians are not well-versed in the nuances of interpreting lead levels, and do not realize that the reference level is a marker of lead exposure, not an indicator of lead toxicity.
This article is essential reading for all pediatricians, emergency practitioners, and toxicologists.