New study reveals high percentages of unsafe blood lead levels among U.S. children

Largest percentage of children with very high blood lead levels concentrated in six regions, including in New York, Pennsylvania and Ohio

Despite four decades of public health efforts to minimize children’s exposure to lead, high percentages of unsafe blood lead levels are still found in children in numerous regions of the United States, according to a new study by researchers at Quest Diagnostics, the world’s leading provider of diagnostic information services.

Published online in the Journal of Pediatrics, the six-year study examined 5,266,408 blood lead levels (BLLs) test results of infants and children under age six in all 50 states and the District of Columbia. The Quest Diagnostics Health Trends™ study is believed to be the largest analysis of BLL test results in children in the United States.

While there is no safe blood lead level in children, the Centers for Disease Control and Prevention (CDC) has identified a blood lead level equal to or greater than five micrograms per deciliter as a threshold to identify children with elevated blood lead levels. The study found that greater than 3.0% of children nationally had blood lead levels at or above this level. High blood lead levels were greater for boys (3.1%) than girls (2.8%), a slight, but statistically significant difference. Despite an unexplained modest increase in 2015, overall, blood lead levels declined in children during the six-year period ending in April 2015.

However, on a regional basis, high percentages of infants and children had blood lead levels equal to or greater than five micrograms per deciliter (high BLLs). In six regions categorized by ZIP code, more than 14 percent of specimens tested had high BLLs. These include three regions in New York (Syracuse, Buffalo and Poughkeepsie), two in Pennsylvania (York and Oil City) and one in Ohio (Cincinnati). The eleven regions with the largest proportions of specimens with very high BLLs (equal to or greater than ten micrograms of per deciliter), were also in New York (Syracuse, Buffalo, Poughkeepsie, Niagara Falls, Binghamton), Pennsylvania (York, Oil City, Reading, Erie), and Ohio (Cincinnati, Cleveland).

The analysis also examined rates by states, finding that those with the highest proportion of high BLLs were Minnesota (10.3%), Pennsylvania (7.8%), Kentucky (7.1%), Ohio (7.0%), and Connecticut (6.7%). California and Florida had the lowest rate of high BLLs (1.4% and 1.1%, respectively) and very high BLLs (0.2% and 0.1%).

From the first year of the study period to its final year, Mississippi had the largest absolute increase in high blood levels (from 3.1% to 6.3%), while New Hampshire demonstrated the largest absolute decline in high blood lead levels (from 9.7% to 2.6%).

In addition, the Quest investigators examined correlations between test results and pre-1950s housing construction, poverty income ratios (PIRs), and health plan enrollment. The study showed that living in an area with a high proportion of pre-1950 housing construction, when the use of lead-based paint was widespread, was strongly associated with having a high blood lead level, confirming prior findings from NHANES. The study also showed children living in ZIP codes with the highest poverty rate had a greater proportion of  high BLL and very high BLL, while children living in ZIP codes with lower rates of poverty were much less likely to exhibit high BLL and very high BLL.

“These alarming findings show that while our nation has made progress in addressing lead exposure, our public health successes are neither complete nor demographically consistent,” said Harvey W. Kaufman, senior medical director, Quest Diagnostics and an author of the study. “We have a long way to go, both in terms of contaminated water and residual lead-based paint, to reduce disparities that put some of our children at disproportionate risk of exposure to lead.

“This Quest Diagnostics study may offer value to healthcare policymakers considering policies to protect young children from long-lasting impacts of exposure, and to clinicians, who may use the geographic findings to guide screening determinations in high prevalence areas,” added Dr. Kaufman.

In May 2012, the CDC Advisory Committee on Childhood Lead Poisoning Prevention (ACCLPP) advised that there is no safe blood lead level, and that even low levels of lead in blood affect IQ, ability to pay attention, and academic achievement. A study funded by the National Institute of Environmental Health Studies (NIEHS) showed that high neonatal blood levels of lead in mothers can cause epigenetic changes in their unborn children. Research suggests the effects of lead exposure appear to be irreversible.

Study Strengths and Limitations

The study's strengths are its size and national scope; the ability to examine narrow sub-groupings of data based on three-digit ZIP codes; and the use of an objective laboratory method, versus surveys or polls, which may be subject to user misrepresentation or error. Study limitations include reliance on testing orders, rather than population sampling; varying volumes of test results in certain states; and the inability to determine values below the threshold of detection. Quest Diagnostics does not provide services to all clinicians in the U.S., so results are not broadly representative of all patients tested in the U.S. Based on analysis of de-identified test results, the study was performed in compliance with applicable privacy regulations and the company's strict privacy policies, and was determined to be exempt from Western Institutional Review Board.