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Rare Earth Elements and Technology-Related Trace Metals in Paediatric Scalp Hair: A 2001 Urban Baseline from Spain.

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Overview

This retrospective biomonitoring study analyzed archival scalp hair specimens collected in April-May 2001 from 120 children (aged 6-9 years) and 97 adolescents (aged 13-16 years) in Alcala de Henares, Spain, a dense urban area approximately 30 km east of Madrid with major traffic corridors and industrial zones. The dataset was designed as a pre-diffusion baseline predating widespread nano-technology, e-mobility, and smartphone expansion. Seventeen analytes were measured by ICP-MS including rare earth elements (Bi, Ce, Er, Gd, La, Nd, Pr, Y), platinum group elements (Ir, Pd, Pt, Rh), and other technology-related trace metals (Rb, Sb, Th, U). Platinum was not detected in any of the 217 participants. The study provides biomonitoring reference ranges for urban paediatric populations at the outset of the 21st century, before the technological transformations expected to increase PGE environmental loading.

Key numbers

Platinum (Pt):

  • Children (n=120): all 120 samples below limit of detection; LoD = 0.00511 micrograms per gram
  • Adolescents (n=97): all 97 samples below limit of detection; LoD = 0.0063 micrograms per gram
  • Platinum could not be characterised statistically in either age group
  • Comparative context: Swedish general population hair median Pt = 0.00008 micrograms per gram; range below 0.00006 to 0.00021 micrograms per gram. The Alcala LoDs (0.005-0.0063 micrograms per gram) are 60-80-fold above the Swedish median, confirming that absence of detections is analytically plausible and that standard multi-element ICP-MS panels are insufficient for characterising population-baseline hair Pt.

Palladium (Pd):

  • Children (n=120): 12 detections (10% above LoD); LoD = 0.00071 micrograms per gram; P95 = 0.00096 micrograms per gram; range 0.00072-0.00492 micrograms per gram
  • Adolescents (n=97): 7 detections (92.8% below LoD); LoD = 0.0012 micrograms per gram; P95 = 0.0015 micrograms per gram; range 0.001-0.002 micrograms per gram

Rhodium (Rh):

  • Children (n=120): 6 detections (5% above LoD); LoD = 0.00176 micrograms per gram; P97.5 = 0.0029 micrograms per gram; range 0.0018-0.00984 micrograms per gram
  • Adolescents (n=97): 6 detections (93.8% below LoD); LoD = 0.00047 micrograms per gram; P95 = 0.0005 micrograms per gram

Iridium (Ir):

  • Children: 1 detection (0.8%); LoD = 0.00181 micrograms per gram; single value 0.00231 micrograms per gram
  • Adolescents: 0 detections (100% below LoD = 0.0025 micrograms per gram)

Light rare earth elements (children, in micrograms per gram, most detected):

  • Ce: median 0.0109; La: median 0.0072; Nd: median 0.0042; Pr: median 0.00137; Gd: median 0.00068; Er: median 0.00035
  • Ubiquitous elements (100% detection): Sb (median 0.033) and uranium (U) (median 0.011)

Statistically significant findings:

  • Sb: boys higher than girls in children (p=0.009); substantial age decline from children to adolescents (p=2.14 x 10^-22)
  • U: girls higher than boys in children (p=0.0004)
  • Zonal differences: Ce, Er, Gd, Pr varied significantly by residential zone (Zone II/IV urban/industrial versus Zone I green) in children

Catalytic converter context:

  • In 2001, approximately 42% of petrol passenger cars in Spain carried catalytic converters (EU-15 average approximately 72%); cited as context for PGE emission levels at the time of sampling

Comparison to Sicilian adolescents near industrial sites (Lo Medico et al.):

  • Median Pt: 0.00008-0.00156 micrograms per gram; range values confirm that detectability in hair is achievable near petrochemical sites, but was below LoD in this urban Spanish cohort

Methods

  • Decontamination: Triton X-100 1% ultrasonication x 4, ultrapure water rinse x 3, dried 50 degrees C
  • Digestion: 100 mg subsample, 2 mL 65% HNO3, 96 degrees C, 12 hours; diluted 1:5 with 1% HNO3
  • Instrument: ICP-MS PerkinElmer NexION 350D, helium collision mode
  • CRMs: NCS DC 73347 human hair and SPS-SW2

Relevance to this wiki

This paper establishes that platinum is effectively undetectable in scalp hair of healthy urban children and adolescents under typical late-20th-century environmental exposure conditions. It quantifies the analytical gap between standard multi-element ICP-MS capability and the population-baseline concentration for hair Pt. It provides biomonitoring reference distributions for palladium and rhodium in the same paediatric cohort. No food occurrence data are contributed.

Update history

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