heavy metal levels in

Overview

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provided the original author(s) and the showing the highest rate (17.39%). Significantly higher blood metal levels
As (p < 0.05). K-means clustering stratified participants into low-, medium-, and
the long - term accumulation of heavy metals may induce health 2.4 K-means cluster analysis
Hunan Provincial Bureau of Statistics, the occupational populations metals (Pb ≤ 200 μg/L, Cd ≤ 2 μg/L, Hg ≤ 5 μg/L, and As ≤
were stratified by occupation type (mining, construction, 10 μg/L). Medium-exposure cluster: Defined by ≥ 1 parameter
manufacturing, agriculture, and others) and geographic region meeting or marginally exceeding OELs (Pb 200–400 μg/L, Cd
(Chang-Zhu-Tan, Xiangnan, Xiangxi, Dongting Lake). Within each 2–5 μg/L, Hg 5–15 μg/L, and As 10–30 μg/L). High-exposure cluster:
registries, and employees were further randomly sampled within OELs (Pb > 400 μg/L, Cd > 5 μg/L, Hg > 15 μg/L, and/or As >
enrollment; and (3) pregnancy, lactation, or childhood. The study were reported as median with interquartile range (M (P25, P75)) and
processed within 24 h to minimize pre-analytical variability. (Table 1). These findings highlight substantial exposure risks that need
TABLE 1 Blood concentrations and exceedance rates of Pb, Cd, Hg, and
significant determinants of blood Pb levels (p < 0.05; Table 3).
status (p < 0.05; Table 4). For blood Hg, significant predictors included
Blood Cd 2.1 (1.1–3.6) 352 11.77 Table 5), whereas blood As levels were significantly influenced by
3.4 K-means clustering-based typology of
Demographic stratification of the occupational cohort (n = 2,991) low-exposure (n = 93, 3.1%), medium-exposure (n = 1,614, 54.0%),
demonstrated the following distributions: gender (male: n = 1,521; and high-exposure clusters (n = 1,284, 42.9%). The high-exposure
female: n = 1,470), age (< 30 years: n = 763; 30–40 years: n = 768; cluster exhibited substantially elevated blood concentrations of Pb,
41–50 years: n = 705; > 50 years: n = 755), employment duration (< Cd, Hg, and As, with all participants exceeding OELs for at least one
5 years: n = 762; 5–10 years: n = 770; 11–20 years: n = 717; > 20 years: metal. In contrast, the low-exposure cluster demonstrated minimal
n = 742), occupation type (mining: n = 626; construction: n = 597; exposure burdens of Pb, Cd, Hg, and As, with all parameters
manufacturing: n = 537; agriculture: n = 625; others: n = 606), remaining far below OELs. The medium-exposure cluster displayed
geographic region (Chang-Zhu-Tan: n = 799; Xiangnan: n = 745; intermediate profiles, where some individuals approached or
Xiangxi: n = 727; Dongting Lake: n = 720), smoking status (smoking: marginally surpassed OELs (Table 7). Radar plot visualization
n = 1,485; non-drinking: n = 1,506). metal exposure profiles.
Table 2) as independent predictors of whole blood Pb, Cd, Hg, and As occupational populations in Hunan Province exhibited significant
TABLE 2 Variable categorization and coding schema. Similarly, an epidemiological investigation on battery factories in
be attributable to the cumulative effect of prolonged occupational mercury-contaminated containers in rural regions (23), indicating the
TABLE 3 Multivariate linear regression analysis of factors influencing blood Pb levels.
TABLE 4 Multivariate linear regression analysis of factors influencing blood Cd levels.
TABLE 5 Multivariate linear regression analysis of factors influencing blood Hg levels.
TABLE 6 Multivariate linear regression analysis of factors influencing blood As levels.
TABLE 7 Blood heavy metal concentrations across K-means-derived exposure clusters.
impacting human health (29, 30). In this study, smokers exhibited habits. K-means clustering analysis further identified a high-exposure

Methods (brief)

Front. Public Health 13:1635236. habits were collected. Whole blood samples were analyzed via atomic
(p < 0.05), including some samples exceeding occupational exposure limits.
as employment duration and occupation type, and lifestyle habits performed using atomic absorption spectrophotometry (11) for Pb
registries, and employees were further randomly sampled within OELs (Pb > 400 μg/L, Cd > 5 μg/L, Hg > 15 μg/L, and/or As >
sectional survey, with sample characteristics closely reflecting the
(hematological disorders, renal dysfunction, or hepatic diseases); (2) samples t-tests (two-group comparisons) or one-way analysis of
Concurrently, whole blood samples were collected from participants
Certified healthcare professionals collected 5 mL of antecubital A cohort of 2,991 occupationally exposed individuals was
venous blood from each participant. Blood samples were immediately analyzed for whole blood concentrations of Pb, Cd, Hg, and As. The
Employment duration 1 = < 5, 2 = 5–10, 3 = 11–20, 4 = > 20 be explained by differences in sample composition, a higher
Exposure cluster Sample size (n) Blood Pb (μg/L) Blood Cd (μg/L) Blood Hg (μg/L) Blood As (μg/L)
Hg concentrations. These findings suggest that smoking may concentrations, with some samples reaching or even exceeding OELs.
scale sample analysis, key factors influencing whole blood heavy metal
despite the large sample size, the coverage of occupation types and 2025051301). The studies were conducted in accordance with the local
low-concentration samples. Finally, potential confounding factors such
mass spectrometry: a comparison with graphite furnace atomic absorption spectrometry. (2022) 194:675. doi: 10.1007/s10661-022-10326-y
cinnabar and AnGongNiuHuang pill to rats. Front Pharmacol. (2022) 13:967608. doi: 29. Shakeri MT, Nezami H, Nakhaee S, Aaseth J, Mehrpour O. Assessing heavy metal

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Update history

The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.

Commit	Date	Change	Description
b01ec52c	2026-08-04	major	2 sections added
d49e450f	2026-08-03	major	5 sections added; narrative text revised