Health Risk for Non-Dietary Children's Exposure to Heavy Metals in Postindustrial Areas in Upper Silesia, Poland

Overview

This study measured cadmium, lead, and zinc in 77 surface soil samples collected from playgrounds, sports fields, gyms, parks, squares, and other recreational areas across three postindustrial districts of Upper Silesia: Katowice-Szopienice (legacy non-ferrous smelter zone), Świętochłowice-Lipiny, and Piekary Śląskie-Brzeziny. The work assesses non-dietary pediatric exposure via three routes (incidental soil ingestion, dermal contact, inhalation of PM10) under three concentration scenarios (S1 minimum, S2 mean, S3 maximum) across three age groups (preschool <6 y, younger school 6 to <12 y, older school 12-15 y), using the US EPA average-daily-dose and hazard-quotient framework with reference doses from the EPA IRIS database (0.001 mg/kg/day cadmium (Cd); 0.3 mg/kg/day Zn; 0.0035 mg/kg/day lead (Pb) derived from the historical PTWI divided by seven). Eighth-grade national-exam results from three schools in the studied districts (2019, 2021, 2024) were compared with city, provincial, and national averages as a supplementary cognitive-outcome readout. Polish legal maximum permissible concentrations (MPC; Regulation of the Minister of Environment, 1 September 2016) and FAO/WHO maximum permissible limits are tabulated alongside the soil data. No food crops, food products, or human tissues are sampled; the paper is a soil-and-exposure study, not a dietary-intake study.

Key numbers

Table 6 — Heavy metal content in soil by recreational-area type (mg/kg dry mass; n=77 across all three districts):

• 65 of 77 samples (84.42 percent) exceeded the Polish MPC for at least one of the three metals.
• 35 of 77 samples (45.45 percent) exceeded the MPC for all three metals simultaneously.
• Per-metal MPC exceedance: Cd 58/77 (75.32 percent); Pb 46/77 (59.74 percent); Zn 44/77 (57.14 percent).
• Across the three districts, mean ranges are Cd 4.09-20.94 mg/kg dry mass, Pb 161.70-1027.68 mg/kg dry mass, Zn 577.76-1475.93 mg/kg dry mass.

Table 7 — Per-district per-area-type mean concentrations and selected maxima (mg/kg dry mass):

• Highest Cd and Pb playground mean concentrations were measured in Katowice-Szopienice (n=24; Cd x̄ 7.75 mg/kg; Pb x̄ 513.67 mg/kg with maximum 4930.10 mg/kg).
• Highest Zn playground mean was measured in Piekary Śląskie (n=13; Zn x̄ 1077.80 mg/kg dry mass; maximum 3528.37 mg/kg).
• The “other” (urban squares, parks, green-area) category in Piekary Śląskie (n=3) carried the highest district-area means: Cd x̄ 20.94 mg/kg (max 27.97), Pb x̄ 1027.68 mg/kg (SD 463.63; max 1594.04), Zn x̄ 2859.65 mg/kg dry mass (max 4159.05).
• Sports-field and gym soils in Świętochłowice-Lipiny carried the highest Zn mean for that area type (n=3; Zn x̄ 1598.53 mg/kg dry mass).

Table 8 — Kruskal-Wallis ANOVA across districts and area types (p-values):

• All pairwise and grouped comparisons gave p > 0.05 (KT vs SW vs PS overall: Cd 0.26, Pb 0.13, Zn 0.12). The authors attribute the lack of statistical significance to high within-category variance.

Table 9 — Preschool children (<6 y) non-cancer health risk by scenario and district:

• Cd HQ: maximum 0.087 (S3 across all locations) — below 1; no significant Cd risk.
• Pb HQ: total-samples S3 HQ = 3.029; Katowice S3 HQ = 3.029 (driven by playground maxima at Szopienice; HQ > 3 for preschool ingestion at the worst-case playground). Świętochłowice S3 HQ = 0.522. Piekary Śląskie S3 HQ = 0.979 (close to but below the threshold).
• Pb scenario S2 (mean) HQ for preschool by district (Table 9): Total Samples 0.2372, KT 0.2770, SW 0.1373, PS 0.2849 — none crosses 1; source p. 9 prose paraphrases this as “about half of the reference dose” (the source’s claimed “HQ range from 0.2 to 0.56, respectively, in SW-KT” does not match the Table 9 S2 row and appears to mix S2 means with the higher S3 PS value 0.9794; the tabulated S2 values are reported here as authoritative).
• Zn HQ: maximum 0.034 (S3); no significant Zn risk in any scenario.

Table 10 — Younger school children (6 to <12 y):

• Pb HQ: total-samples S3 = 1.329; Katowice S3 = 1.329 — significant non-cancer risk on the worst-case Katowice playground. Świętochłowice S3 = 0.229; Piekary Śląskie S3 = 0.430.
• Cd and Zn HQ remain well below 1 across all scenarios and districts.

Table 11 — Older school children (12-15 y):

• No HQ value exceeds 1 in any scenario or district. Maximum Pb HQ is 0.248 (S3 Katowice across all locations).

Tables 12-14 — Total non-cancer hazard index (HI = HQ_Pb + HQ_Cd + HQ_Zn):

• Preschool children: HI(S3) = 3.150 across all locations; HI(S3) = 3.150 at Katowice; HI(S3) = 0.608 at Świętochłowice; HI(S3) = 1.069 at Piekary Śląskie. Playground-only HI(S3) at Katowice = 3.112.
• Younger school children: HI(S3) = 1.382 across all locations; HI(S3) = 1.382 at Katowice; HI(S3) ≤ 0.469 at the other two districts.
• Older school children: HI(S3) maximum 0.258; no scenario crosses the HI = 1 threshold.

Table 15 — Dermal exposure daily dose (negligible across all age groups; range spans the per-age-group min to max):

• Cd: 2.4 × 10⁻¹⁰ to 6.3 × 10⁻⁸ µg/kg/day (preschool 3.5 × 10⁻¹⁰ to 6.3 × 10⁻⁸; younger school 3.3 × 10⁻¹⁰ to 5.87 × 10⁻⁸; older school 2.4 × 10⁻¹⁰ to 4.2 × 10⁻⁸).
• Pb: 7.82 × 10⁻⁹ to 7.72 × 10⁻⁶ µg/kg/day (preschool 1.15 × 10⁻⁸ to 7.72 × 10⁻⁶; younger school 1.09 × 10⁻⁸ to 7.19 × 10⁻⁶; older school 7.82 × 10⁻⁹ to 5.17 × 10⁻⁶).
• Zn: 4.65 × 10⁻¹¹ to 7.43 × 10⁻⁹ mg/kg/day (preschool 6.83 × 10⁻¹¹ to 7.43 × 10⁻⁹; younger school 6.52 × 10⁻¹¹ to 6.92 × 10⁻⁹; older school 4.65 × 10⁻¹¹ to 4.98 × 10⁻⁹).
• Authors conclude dermal route contributes negligibly to total non-dietary exposure.

Table 16 — Inhalation exposure from PM10 (National Environmental Monitoring data, Katowice station, 2023 and 2024):

• Cd air concentration (ng/m³): mean 0.63 (2023), 0.76 (2024); maximum 1.71 (2023), 4.72 (2024).
• Pb air concentration (µg/m³): mean 0.025 (2023), 0.021 (2024); maximum 0.094 (2023), 0.083 (2024).
• Preschool inhalation ADD Cd: mean 0.344 ng/kg/d (2023), 0.411 ng/kg/d (2024); maximum 2.563 ng/kg/d (2024).
• Preschool inhalation ADD Pb: mean 0.014 µg/kg/d (2023), 0.011 µg/kg/d (2024); maximum 0.051 µg/kg/d (2023).
• Zn was not measured at the inhalation monitoring station.
• Authors conclude the inhalation route is more important than dermal but still well below the ingestion route in this setting; ingestion > inhalation > dermal.

Table 17 — Eighth-grade national-exam results (2019, 2021, 2024) for schools in the studied districts vs city/provincial/national averages:

• Across all three years, Polish-language, mathematics, and English-language scores at PSC No. 19 (Świętochłowice-Lipiny) and PSC No. 42 (Katowice-Szopienice) ran below city, provincial, and national means, with the lowest scores observed at PSC No. 19 in Lipiny.
• 2024 results at PSC No. 19 Lipiny: Polish 31.1 percent (national 61); Mathematics 22.1 percent (national 52); English 43.38 percent (national 66).
• The authors interpret this readout as consistent with the lead-exposure neurotoxicity hypothesis but note that socio-economic conditions in these districts are an alternative or contributing explanation.

Evidence Fitness

EF-3 (Geographic exposure context). This source supplies recreational-soil occurrence values and US-EPA-framework non-dietary exposure / non-cancer risk estimates for Cd, Pb, and Zn in three named postindustrial districts of Upper Silesia, Poland. It supports geographic-context reporting on metals/lead, metals/cadmium, and metals/zinc for European legacy non-ferrous smelter regions, and supports a pediatric non-dietary-exposure narrative for incidental soil ingestion. It does not support ingredient or food-product occurrence claims (no food sampling), it does not measure arsenic (As), mercury (Hg), chromium (Cr), or nickel (Ni), and the cognitive-outcome (eighth-grade exam) readout is observational and confounded by socio-economic variables that the authors themselves acknowledge.

Methods (brief)

• Sampling: 77 surface soil samples (0 to 0.25 m depth) collected from playgrounds, sports fields, gyms, and other recreational areas across Katowice-Szopienice, Świętochłowice-Lipiny, and Piekary Śląskie-Brzeziny. Several individual sub-samples taken per site to produce a representative 0.5 kg composite, transferred to zip-lock bags.
• Sample preparation: composite samples cleaned of stones and plant debris, dried at 105 °C to constant mass in a POL-EKO-APARATURA SLW 75 SMART laboratory dryer, sieved to <2 mm through an EML200 Pure HAVER&BOECKER (VWR) screen.
• Digestion: 0.5 g (±0.015 g) of each sieved sample digested in 10 mL 65 percent ultrapure HNO₃ (Merck) plus 1 mL 30 percent H₂O₂ (Stanlab) in a Teflon vessel using a Milestone ETHOS UP multi-station microwave mineralizer over a three-stage program (20 min at 210 °C / 1800 W; 15 min at 210 °C / 1800 W; 30 min cooling). Digests filtered into volumetric flasks and made up with ultrapure water.
• Instrumentation: Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) on a Horiba Scientific Ultima Expert spectrometer at the PCA-accredited Analytical Laboratory (AB1717), Department of Environmental Health, Medical University of Silesia. Emission lines: Zn 206.201 nm, Pb 220.353 nm, Cd 228.802 nm. Linearity R² ≥ 0.999 for all three analytes.
• LOD: 1.43 mg/kg (Zn), 5.80 mg/kg (Pb), 0.06 mg/kg (Cd). LOQ: 3.28 mg/kg (Zn), 12.68 mg/kg (Pb), 0.15 mg/kg (Cd). Accuracy RSD <10 percent. Repeatability R <20 percent.
• QA/QC: calibration with CPAchem (Bogomilovo, Bulgaria) certified reference solutions for Pb (C041.2NP.L1), Cd (C010.2NP.L1), Zn (C069.2NP.L1) at 1000 mg/L in 2 percent HNO₃. Method correctness verified using clay-soil CRM (Trace Metals-Clay 1, CRM046-50G; Sigma Aldrich, Laramie, WY, USA) with recoveries 81-105 percent (Zn), 92-118 percent (Pb), and 87-99 percent (Cd).
• Exposure assessment: US EPA ADD formula ADD = (MC × IR × CF)/BW for ingestion; analogous dermal and inhalation ADD formulas using exposure factors from US EPA [9,44,45,47]. Age-stratified body weight and soil-ingestion rate: 18.6 kg / 40 mg/day (1 to <6 y), 31.8 kg / 30 mg/day (6 to <12 y), 56.8 kg / 10 mg/day (12-15 y). Reference doses: 0.001 mg/kg/day (Cd), 0.3 mg/kg/day (Zn), 0.0035 mg/kg/day (Pb, derived from the historical PTWI divided by seven per current Polish practice in the absence of an EPA IRIS RfD for Pb). HQ = ADD/RfD; HI = HQ_Pb + HQ_Cd + HQ_Zn. Carcinogenic risk was not calculated because IRIS does not provide CSF values for Pb, Cd, or Zn.
• Inhalation exposure was estimated from National Environmental Monitoring (Chief Inspectorate of Environmental Protection) Cd and Pb concentrations in PM10 at the Katowice station for 2023 and 2024; Zn was not measured at that station.
• Statistical analysis: Statistica 13.3 (StatSoft, Kraków, Poland). Normality tested by Shapiro-Wilk; concentration data were non-normal (p < 0.05), so Kruskal-Wallis ANOVA on ranks and Mann-Whitney U tests were used for between-group comparisons.

Implications

• Certification: Provides Upper Silesia regional non-dietary exposure context for Pb and Cd in recreational soils, with the Katowice-Szopienice district showing preschool Pb HQ above 3 and total HI above 3 at the worst-case playground site. Useful as European-legacy-smelter-region geographic context on metals/lead and metals/cadmium, and as a non-dietary-route comparator when assessing combined dietary-plus-non-dietary infant and child lead exposure. Does not directly inform HMTc per-analyte food thresholds because no food matrix is sampled.
• Courses: Strong worked example of US-EPA-framework non-cancer health risk assessment for pediatric non-dietary exposure to legacy smelter contamination, including age-stratified ADD calculation, three-scenario sensitivity analysis, and route partitioning (ingestion > inhalation > dermal). The eighth-grade-exam comparison is also a useful teaching case in how environmental-health studies attempt cognitive-outcome readouts under heavy socio-economic confounding.
• App: Could support a geographic-adjustment factor for European non-ferrous smelter legacy regions for soil-derived Pb and Cd exposure, but only via a separate non-dietary exposure model; the app’s primary scope is dietary exposure inferred from ingredient lists, and this paper does not contribute to that model.
• Microbiome: Not addressed.

Related evidence

• Lead
• Cadmium
• Zinc

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