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TOPLINE:

Blood lead levels (BLLs) in children aged ≤ 5 years continue to decline nationally, with geometric mean BLLs dropping from 0.97 μg/dL in 2011-2012 to 0.53 μg/dL in 2021-2023. However, state surveillance data from seven states reveal persistent disparities, with more than 32,000 children having BLLs ≥ 5 μg/dL in 2021 alone, including 186 children with levels ≥ 45 μg/dL, despite no children in the national sample exceeding 5 μg/dL.

METHODOLOGY:

• Researchers analyzed National Health and Nutrition Examination Survey (NHANES) data from children aged ≤ 5 years across survey cycles 2011-2012, 2013-2014, 2015-2016, and 2021-2023, with sample sizes ranging from 301 to 818 participants per cycle.
• Analysis calculated weighted geometric means for BLLs overall and by sociodemographic characteristics including gender, race and ethnicity, nativity status, and household poverty income ratio, using NHANES Mobile Examination Center blood metal 2-year weights and accounting for nonrandom sampling design.
• Investigators estimated the percentage of children with BLLs above thresholds of 3.5 μg/dL and 5.0 μg/dL, with variance estimated via Taylor series linearization and 95% Wald confidence intervals constructed for continuous BLLs.
• State-level data from seven states in the United States were collected on the percentage of children with BLLs ≥ 3.5 μg/dL or ≥ 5 μg/dL by race and ethnicity between 2020 and 2023, targeting children enrolled in Medicaid.
• Childhood Blood Lead Surveillance System data from 30 states reporting between 2017 and 2021 were included, representing more than 15 million children younger than 72 months screened for BLLs.

TAKEAWAY:

• Overall BLL geometric mean (GM) declined between 2011 and 2023 for available NHANES years (P trend < .001), with only 1.9% of sampled children having BLLs above 3.5 μg/dL and no children having BLLs ≥ 5.0 μg/dL in 2021-2023.
• Black, non-Hispanic children showed the greatest decline, with the GM decreasing from 1.29 μg/dL in 2011-2012 to 0.58 μg/dL in 2021-2023 (P trend < .001), and the GM mean difference between Black and White children was no longer statistically significant in 2021-2023 (Black non-Hispanic GM, 0.58 μg/dL; 95% confidence interval [CI], 0.50-0.68 μg/dL; White non-Hispanic GM, 0.51 μg/dL; 95% CI, 0.44-0.59 μg/dL).
• State surveillance data indicated 152,571 children had BLLs of 5-9 μg/dL and 57,496 had levels ≥ 10 μg/dL between 2017 and 2021, with 32,144 children with BLLs ≥ 5 μg/dL reported in 2021 alone.
• In Massachusetts in 2022, the prevalence of children with BLLs ≥ 5 μg/dL was 3.6 times greater in communities with the highest percentages of families at ≤ 200% of the federal poverty threshold compared with communities in the highest income quartile (19.5 per 1000 children vs 5.4 per 1000 children).

IN PRACTICE:

"National data indicate disparities, but state and local BLL data may provide benchmarks to target prevention efforts and warn of emerging risks," wrote the authors of the study.

SOURCE:

The study was led by Mary Jean Brown, ScD, RN, Harvard T.H. Chan School of Public Health in Boston. It was published online on June 11 in American Journal of Public Health.

LIMITATIONS:

The 2021-2023 NHANES BLL data for children aged 1-5 years were based on a much smaller sample size (n = 301) compared with previous years, allowing only limited subgroup analyses. NHANES BLL data for children aged 0-5 years were not publicly released in 2017-2018 and combined 2017 to March 2020 due to privacy concerns, and data collection was halted in 2019-2020 because of COVID-19, creating gaps that prevented continuous comparisons. State-based BLL data are collected in pediatric clinical settings and limited by several factors, including that surveillance systems are not designed to estimate population distribution but rather to identify children with elevated BLLs, and reasons for testing vary across clinical settings, which could introduce bias if children more likely to be exposed are more likely to be tested. Blood samples are sent to many different laboratories using various analytic techniques with different levels of detection, and data are not standardized across states regarding BLL thresholds considered elevated or collection and reporting of race and ethnicity data. The study is limited by lack of data from the southern United States, where well-known risk factors such as poverty and older housing suggest lead exposure occurs.

DISCLOSURES:

Christian Hoover received support in part from National Institutes of Health grant F31ES036867. Mary Jean Brown disclosed receiving compensation for technical assistance and advice from Meridien Scientific, the maker of LeadCare blood lead testing instruments, and from attorneys general in Massachusetts and the District of Columbia for work on childhood lead exposure effects. David C. Bellinger disclosed receiving compensation for providing expert testimony in legal cases involving childhood lead poisoning. The remaining study authors reported no relevant conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.