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Concentrations and determinants of lead, mercury, cadmium, and arsenic in pooled donor breast milk in Spain

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Overview

Freire and colleagues measured lead, mercury, cadmium, and arsenic in pooled donor breast milk from a Spanish human milk bank. The study is routeable for human-milk exposure evidence because it reports detection frequencies and median milk concentrations for 242 pooled samples from 83 donors. It also identifies donor and dietary predictors of metal concentrations.

Key numbers

  • Sample frame: 242 pooled breast milk samples from 83 donors, collected in Spain from 2015 to 2018.
  • Detection frequencies: As 97.1%, Hg 81.2%, Pb 50.6%, and Cd 38.0%.
  • Median breast milk concentrations: As 1.49 µg/L, Hg 0.26 µg/L, Pb 0.14 µg/L, and Cd <0.04 µg/L.
  • Hg was higher in donors with greater intake of fatty fish and meat and lower in samples collected later postpartum.
  • Cd detection was associated with university education, fried and canned food intake, and more frequent hand-cream use in the authors’ model.

Methods (brief)

Milk samples were microwave-digested in quartz vessels with HNO3 using an Ethos UP system (Milestone, Shelton, CT, USA) and analyzed by inductively coupled plasma mass spectrometry on an Agilent 8900 triple quadrupole ICP-MS. Quality control used certified reference materials NIST SRM 1640a Trace Elements in Natural Water and ERM-BD151 Skimmed milk powder. Limits of detection were 0.10 µg/L for Pb, 0.05 µg/L for Hg, 0.04 µg/L for Cd, and 0.40 µg/L for As. Values below the LOD were imputed by the LOD divided by the square root of 2. The source reports total As and total Hg, not inorganic arsenic or methylmercury. Predictors of Hg and As concentrations were modeled with mixed-effect linear regression; predictors of Pb and Cd detection (above vs. below LOD) were modeled with mixed-effect logistic regression, with donor ID as a random cluster variable.

Implications

Certification: This source is human-milk exposure context and should not be pooled with infant formula or cow milk.

Courses: Useful for explaining donor-milk exposure, detection frequency, and dietary predictors.

App: Can support infant feeding exposure context where human milk is represented separately from products.

Update history

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