Kuzan et al. (2025) performed ICP-OES multi-element analysis on 33 placentas from women delivering in Wroclaw (Lower Silesia, Poland), measuring eleven elements: the macroelements Ca, Mg and Fe; the microelements Cu, Cr, Mn and Zn; and the toxic / non-essential metals Cd, Pb, Co and Ni. The central toxicological finding is that all four heavy metals (Cd, Co, Ni, Pb) fell below the ICP-OES limits of detection in every sample. The authors had expected at least Cd and Pb to be detectable in some placentas given the Lower Silesia industrial history and their group’s prior detection of these elements in aortic tissue from the same region using the same instrumentation; the absence of any signal in placenta is reported as a null finding rather than as evidence of zero exposure. The study additionally characterised inter-element correlations within placenta and correlations between placental elemental content and selected maternal blood parameters.
Key numbers
| Analyte | LOD | Detection result | Reported in |
|---|---|---|---|
| Cd | < 0.13 µg/L | Not detected in any sample (n=33) | µg/g of tissue |
| Co | < 0.38 µg/L | Not detected in any sample (n=33) | µg/g of tissue |
| Ni | < 0.69 µg/L | Not detected in any sample (n=33) | µg/g of tissue |
| Pb | < 2.4 µg/L | Not detected in any sample (n=33) | µg/g of tissue |
| Ca | — | Detected in all samples | mg/g of tissue |
| Mg | — | Detected in all samples | mg/g of tissue |
| Fe | — | Detected in all samples | mg/g of tissue |
| Cr | — | Detected in all samples | µg/g of tissue |
| Cu | — | Detected in all samples | µg/g of tissue |
| Mn | — | Detected in all samples | µg/g of tissue |
| Zn | — | Detected in all samples | µg/g of tissue |
The paper reports inter-element correlation coefficients and per-element scatter plots but does not publish per-element summary means or standard deviations for the placental concentrations; any “typical placental concentration” derived from this study would have to be back-calculated from the raw data, which is available on author request.
Statistically significant inter-element Spearman correlations in placenta: Ca–Mg r=0.91 (p<0.001), Mg–Zn r=0.76 (p<0.001), Fe–Mn r=0.75 (p<0.001), Cr–Fe r=0.63 (p<0.001), Fe–Zn r=0.58 (p<0.001), Mn–Zn r=0.56 (p=0.001), Ca–Zn r=0.53 (p=0.002), Fe–Cu r=0.45 (p=0.011), Cr–Zn r=0.41 (p=0.019), Cu–Mn r=0.41 (p=0.021).
Statistically significant placenta-element to maternal-blood-parameter correlations: placental Ca and maternal pre-delivery RBC r=0.61; placental Mg and pre-delivery RBC r=0.57; placental Mn and pre-delivery HGB r=0.55; placental Mn and pre-delivery HCT r=0.57; placental Cu and umbilical artery pulsatility index r=−0.57; placental Cu and pre-delivery platelet count r=−0.60; placental Fe and pre-delivery platelet count r=−0.56.
No statistically significant correlations were found between placental elemental content and gestational diabetes, smoking (nicotinism), or premature delivery (point-biserial / logistic regression on 0/1 features). No statistically significant correlations were found between placental elemental content and newborn birth weight, body length, Apgar score, maternal age, maternal BMI, or length of hospitalisation.
Critical methodological note. The non-detection of Cd, Pb, Ni and Co reflects the sensitivity of the chosen platform (Agilent 5110 SVDV ICP-OES) and the tissue-digest dilution used here, not absence of these metals from the placentas. The reported LODs (e.g. Pb < 2.4 µg/L in the digestate) are higher than typical ICP-MS detection capabilities for human placenta, where Pb and Cd are routinely measurable in the µg/kg-wet-weight range. The authors discuss this explicitly: their prior aortic-tissue work from the same region using the same instrument did detect Cd and Pb, so the placental nulls cannot be attributed to instrumentation failure, but they also cannot be interpreted as evidence that these metals are absent. The paper is framed as a pilot study (n=33) with the result that placental burden of Cd/Pb/Ni/Co in this Lower Silesian cohort is below ICP-OES sensitivity.
Methods (brief)
Instrument: Agilent 5110 SVDV ICP-OES (synchronous vertical dual view) with 1.8 mm injector standard quartz torch, Seaspray nebuliser, double-pass glass cyclonic spray chamber. Sample preparation: placental tissue washed three times in deionised water to remove blood, air-dried for two hours, weighed. Acid digest: transfer to a Teflon vessel containing 25 mL of 1 M ultrapure HNO₃ (Sigma-Aldrich), microwave reactor for 90 min under microwave-stimulated hydrothermal conditions at 25 atm and 250 °C, repeated for every specimen. The authors reference Kuzan et al. (2021) for the digestion procedure they modified. Element concentrations were determined as mg/L in the digestate and recalculated to mg/g of tissue for macroelements (Ca, Mg, Fe) and µg/g of tissue for microelements (Cr, Cu, Mn, Zn). The paper does not report use of a certified reference material, internal standard, or matrix-matched calibration; LODs are reported numerically but the validation procedure behind them is not described. Statistical analysis: Kendall’s Tau-b correlation for length of hospitalisation and Apgar score; Spearman correlation for all other continuous parameters; point-biserial correlation and logistic regression for binary outcomes (diabetes, nicotinism, premature delivery). Outliers were not removed. Significance level p < 0.05. Software: Statistica 13.3.
Implications
Certification: This study contributes a null result for Cd, Pb, Ni and Co in placental tissue from a Lower Silesian cohort using ICP-OES at the LODs cited above. HMTc should not cite this as evidence that placental metal transfer is absent or that maternal heavy-metal exposure in industrialised regions is low; the platform LODs are above concentrations at which placental Pb and Cd are routinely detected by ICP-MS. The study is useful as a calibration point for the sensitivity gap between ICP-OES and ICP-MS in placental matrices, and as confirmation that essential-element ratios (Ca:Mg, Fe:Mn, Mg:Zn) co-vary tightly in placenta — an observation relevant to anaemia and oxidative-stress framing of pregnancy nutrition.
Courses: Strong teaching example for distinguishing analytical non-detection from biological absence, and for the principle that method LOD selection drives what a study can and cannot conclude. The authors are explicit about this limitation in their discussion, which makes the paper additionally useful as a model of honest pilot-study reporting.
App: Not directly applicable. Placenta is not a food matrix and this study does not report consumption-side exposure data.
Verification notes
2026-05-18 — Major merge-enhance rewrite of an earlier version of this page that contained multiple non-source-traceable claims. Corrections, each verified against the source PDF:
- Authors. Prior page listed “Kuzan A, Kula A, Kula P, Piatek L, Rybak Z, Timler D”; these names do not appear in the paper. Corrected to the actual author list: Kuzan A, Królewicz E, Kardach M, Rewak-Soroczyńska J, Kowalska M, Moleda A, Wiglusz RJ.
- Title. Prior page used a truncated/incorrect title (“…Maternal Blood Parameters”). Corrected to the published title (“…Maternal and Neonatal Parameters: A Cross-Sectional ICP-OES Study in Lower Silesia”).
- Metals list. Prior page included Se and Sr; neither element is analysed or mentioned in this paper. Prior page omitted Cr, which is one of the eleven analytes. Corrected to the actual list: Cd, Pb, Ni, Co, Cr, Ca, Mg, Fe, Mn, Cu, Zn.
- raw_path. Prior path pointed to a file that does not exist in
raw/Papers Cube Manual Fetch/. Corrected to the actual filename. - Sample population. Prior page described the cohort as “singleton uncomplicated pregnancies, gestational age 37–42 weeks”. The paper’s inclusion criterion is 22–42 weeks (not 37–42), and the cohort includes diabetes (30.3%), hypothyroidism (21.2%), PROM (12.2%) and nicotinism (9.1%), so “uncomplicated” is incorrect.
- Delivery mode counts. Prior page reported “21 vaginal, 12 caesarean”. Paper reports 2 spontaneous (6.1%) and 31 caesarean (93.9%) — essentially reversed.
- Mean placental concentrations. Prior page included a column of “Mean (if detected)” values (1,456 µg/g Ca; 337 µg/g Mg; 1,289 µg/g Fe; etc.). The paper does not publish per-element summary means or SDs; these numbers do not appear anywhere in the source. Removed.
- Methods details. Prior page asserted: biopsies from “the central cotyledon”, “freeze-dried”, digested with “HNO₃/H₂O₂”, “Anton Paar Multiwave 5000”, “matrix-matched external calibration”, and CRM validation with “NIST SRM 1577c bovine liver”. None of these specifics appears in the paper. Corrected methods to what the paper actually states: deionised-water rinse ×3, air-dried two hours, 25 mL 1 M HNO₃ in Teflon vessel, microwave reactor 90 min at 25 atm / 250 °C; no CRM, internal standard, or matrix-matched calibration reported.
- Statistical analysis. Prior page listed “Pearson and Spearman correlations; Student’s t-test for delivery mode comparison”. The paper uses Kendall’s Tau-b (for hospitalisation length and Apgar), Spearman (for other continuous variables), and point-biserial correlation / logistic regression (for binary outcomes). No Pearson, no t-test on delivery mode.
- Units. Prior page reported all detected-element concentrations as “µg/g dry weight”. Paper reports Ca, Mg and Fe in mg/g of tissue and Cr, Cu, Mn, Zn in µg/g of tissue; “dry weight” is not the reporting basis (samples were air-dried rather than freeze-dried).
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Page history
The five most recent substantive edits to this page. 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 | Description |
|---|---|---|
| b0f3d38 | 2026-06-12 | batch | corpus rescreen b04 old terminal skips |