Abstract

Background
Lead toxicity manifests at blood lead concentrations (BPb) well below the limits stipulated in Korea's occupational regulations, which set a surveillance trigger at 30 μg/dL and an occupational-disease threshold at 40 μg/dL. This study investigated subclinical effects in a Korean population with low exposure and assessed whether these findings could inform revision of Korea's occupational blood-lead regulations.
Methods
Data from three Korean National Environmental Health Survey cycles were analyzed (KoNEHS 3–5, 2015–2023; adults ≥19 years). Whole-blood lead was measured by inductively coupled plasma mass spectrometry. BPb distributions were summarized by cycle, sex, age, and occupation. Covariate-adjusted partial correlations (r) between log-BPb and erythropoietic markers (hemoglobin, hematocrit, red blood cell [RBC] count, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration [MCHC]), glycemic (glycated hemoglobin [HbA1c]), and renal glomerular filtration rate (serum β2-microglobulin [β2-MG]) biomarkers were computed across six BPb cut-offs (1.0–3.5 μg/dL) and characterized with restricted cubic splines.
Results
The weighted geometric mean (GM) BPb was 1.52 μg/dL (P97.5 4.03 μg/dL). Inter-occupational differences in BPb remained modest after adjusting for key covariates (sex, age, cycle, smoking, alcohol, exercise). Hemoglobin, hematocrit, and RBC count rose at low BPb but reversed to negative correlations above ≈2.2–2.5 μg/dL, reaching r ≈ −0.10 to −0.15 above 3.0 μg/dL; MCHC showed a weaker reversal (≈1.7 μg/dL). The hematologic sign-reversal persisted within risk occupations and most sex-age strata, most pronounced in men. Serum β2-MG increased monotonically with blood lead (adjusted pcur = 0.002, plin < 0.001), and HbA1c declined monotonically.
Conclusions
In a representative Korean sample, blood lead levels show subclinical hematologic signals below 3 μg/dL, far below the current occupational reference values, indicating that these values are unlikely to remain appropriate and that their revision is warranted. The phased strengthening presented as an illustrative policy scenario should proceed through scientific evaluation followed by stakeholder consultation to ensure both health protection and feasibility.

• Keywords: Blood lead; KoNEHS; low-level exposure; occupational exposure ; erythropoietic markers