Kuzan et al. (2025) performed ICP-OES multi-element analysis on 33 term placentas from the Lower Silesia region of Poland, profiling twelve elements (Ca, Mg, Fe, Mn, Cu, Zn, Se, Sr, Co, Ni, Pb, Cd) and correlating placental concentrations with maternal blood parameters (CBC, CMP, lipid panel). The central toxicological finding is that none of the toxic heavy metals measured (Cd, Pb, Ni, Co) were detected above the instrument’s limits of detection in any of the 33 samples, which constitutes a meaningful null result in a region known for legacy industrial pollution. Significant positive correlations were found between biologically coupled essential elements (Ca-Mg r=0.91, Fe-Mn r=0.746), and between Cu and platelet count (inverse), and Mn and hemoglobin.
Key numbers
| Analyte | LOD (µg/L) | Detection result | Mean (if detected) |
|---|---|---|---|
| Cd | 0.13 | Not detected in any sample (n=33) | — |
| Pb | 2.4 | Not detected in any sample (n=33) | — |
| Ni | 0.69 | Not detected in any sample (n=33) | — |
| Co | 0.38 | Not detected in any sample (n=33) | — |
| Ca | — | Detected all samples | 1,456 µg/g dry weight (approx.) |
| Mg | — | Detected all samples | 337 µg/g dry weight (approx.) |
| Fe | — | Detected all samples | 1,289 µg/g dry weight (approx.) |
| Mn | — | Detected all samples | 1.64 µg/g dry weight (approx.) |
| Cu | — | Detected all samples | 3.14 µg/g dry weight (approx.) |
| Zn | — | Detected all samples | 31.5 µg/g dry weight (approx.) |
| Se | — | Detected all samples | 0.71 µg/g dry weight (approx.) |
| Sr | — | Detected all samples | 2.14 µg/g dry weight (approx.) |
Significant correlation pairs: Ca-Mg (r≈0.91, strongest); Fe-Mn (r=0.746); Cu inversely correlated with platelet count; Mn positively correlated with hemoglobin. Maternal age range 21-39 years; BMI range 18-32 kg/m². No gestational diabetes, hypertension, or preeclampsia in any case. Delivery mode: 21 vaginal, 12 caesarean. No significant difference in metallomic profile by delivery mode.
Critical methodological note: The non-detection of Cd, Pb, Ni, and Co is at least partly a function of the LODs of ICP-OES (Agilent 5110 SVDV), which are relatively high compared to ICP-MS. The LOD for Pb of 2.4 µg/L in acid-digested tissue corresponds to a detection capability that would miss Pb concentrations well within the range reported by ICP-MS studies in placenta from other European cohorts. These non-detections should be interpreted as “below ICP-OES detection limits” rather than as evidence that the placentas are completely Pb- or Cd-free.
Methods (brief)
Instrument: ICP-OES (Agilent 5110 SVDV). Sample preparation: placental biopsies (~1 g wet weight) from the central cotyledon, washed with ultrapure water, freeze-dried, microwave-acid digested with HNO3/H2O2 (Anton Paar Multiwave 5000). Matrix-matched external calibration; CRM validation (NIST SRM 1577c bovine liver). LODs for each element verified per batch. Statistical analysis: Pearson and Spearman correlations; Student’s t-test for delivery mode comparison.
Implications
Certification: The null result on Cd and Pb in placenta from Lower Silesia — a heavily industrialized region — is potentially reassuring but methodologically limited by ICP-OES sensitivity. HMT&C should not cite this study as evidence that placental metal transfer is absent; it is evidence that concentrations are below relatively high ICP-OES detection thresholds. ICP-MS studies on placenta routinely detect Pb and Cd at concentrations below these LODs.
Courses: Excellent example for teaching the distinction between “not detected” and “absent,” and for illustrating how choice of analytical method (ICP-OES vs ICP-MS) affects detection capability and interpretation of non-detect results.
App: Not directly applicable (placenta is not a food matrix). Provides indirect evidence on maternal-to-fetal metal transfer pathways.