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Comparison between pollutants found in breast milk and infant formula in the last decade: A review

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Overview

This is a narrative review by a research team at the University of Seville (Spain) summarizing detected pollutants in breast milk and infant formula across studies published between 2012 and 2022. The authors searched PubMed/MEDLINE and Scopus, identified 2412 breast-milk and 3053 infant-formula candidate records, screened and assessed for eligibility, and included 65 breast-milk studies and 73 infant-formula studies. The review groups contaminants into seven categories: metals and metalloids, chemical compounds derived from heat treatment (acrylamide, 3-MCPD, 2-MCPD, glycidol, PAHs, HMF, furan, dioxins and PCBs), pharmaceuticals (antibiotics, isoflavonoid phytoestrogens, veterinary drug residues), mycotoxins (AFM1, OTA, DON, ZEN, FBs, T2/HT-2), pesticides (OCPs, OPPs, carbamates, pyrethroids, neonicotinoids), packaging-derived contaminants (PFAS, bisphenols, phthalates), and other emerging pollutants (chlorinated paraffins, brominated flame retardants including PBDEs/HBCDD/TBBPA, parabens, benzophenones, mineral oil hydrocarbons). The authors conclude that breast milk most commonly carries metals and pesticides while infant formula most commonly carries metals, mycotoxins, and packaging-derived contaminants, and frame feeding choice as case-dependent on the maternal-environment exposure profile rather than a universal preference.

For the Heavy Metal Index, the load-bearing portions are Section 3.1 (metals) with Tables 3 (breast milk) and 4 (infant formula), Table 1 (regulatory limits in formula and calculated TDI-derived intakes by age band), and the metal-relevant discussion. The non-metal contaminant categories (Sections 3.2–3.7, Tables 5–16) are summarized at the description level so that future syntheses can locate the underlying primary studies through this review, but their numeric findings are out of HMI scope and are not reproduced in the Key numbers section below.

Key numbers

The review reproduces values from the constituent studies as the original authors reported them (means ± SD, medians and ranges, or detection-frequency summaries). Units in the source tables are inconsistent — Table 3 (breast milk) is mostly in µg/L, Table 4 (infant formula) is mostly in µg/kg as-placed-on-market — and that mixed-basis labeling is preserved here. All numbers below are exactly as printed by Martín-Carrasco et al.; they have not been re-normalized.

Regulatory and intake reference values (Table 1, condensed for metals; calculated TDI-derived intakes at 3-month/6-month/12-month body weights of 6.5/8/9.5 kg):

  • lead (Pb): threshold in formula 20 µg/kg; TDI 3.57 µg/kg b.w.; calculated 23.21 / 28.56 / 33.92 µg.
  • cadmium (Cd): threshold in formula 20 µg/kg; TDI 0.36 µg/kg b.w.; calculated 2.34 / 2.88 / 3.42 µg.
  • arsenic (As) (total): threshold in formula 2.1 µg/kg; TDI 0.3 µg/kg b.w.; calculated 1.95 / 2.4 / 2.85 µg.
  • mercury (Hg): TDI 4 µg/kg b.w. (maximum recommended; no explicit TDI); calculated 26 / 32 / 38 µg.
  • methylmercury (MeHg): TDI 1.6 µg/kg b.w.; calculated 10.4 / 12.8 / 15.2 µg.
  • aluminum (Al): threshold in formula 286 µg/kg; TDI 1000 µg/kg b.w.; calculated 6500 / 8000 / 9500 µg.
  • chromium (Cr): threshold in formula 10 µg/100 kcal; TDI 2.8 µg/kg b.w.; calculated 18.2 / 22.4 / 26.6 µg.
  • tin (Sn): threshold in formula 50,000 µg/kg; TDI 14,000 µg/kg b.w.; calculated 9100 / 11,200 / 13,300 µg.
  • nickel (Ni): threshold in formula 2.8 µg/kg; TDI 1.1 µg/kg b.w.; calculated 7.15 / 8.8 / 10.45 µg.

Selected breast-milk metals findings, Table 3 (as reported; mean ± SD or median:range; µg/L unless noted):

  • Morocco (Cherkani-Hassani et al. 2021b), n=70, ICP-MS: Pb 23.08 ± 62.75.
  • Nigeria (Ekeanyanwu et al. 2020), n=225 stratified by maternal age, HPLC-AAS: by age band 18–25 y (n=34) Cd 25 ± 13, Cr 20 ± 13, Cu 34 ± 11, Fe 51 ± 59, Pb 44 ± 13, Zn 7 ± 51; 26–30 y (n=118) Cd 31 ± 14, Pb 39 ± 12; 31–35 y (n=45) Cd 28 ± 13, Pb 39 ± 15; 36–40 y (n=28) Cd 27 ± 16, Pb 31 ± 12.
  • Zimbabwe (Bose-O’Reilly et al. 2020), n=120 stratified by Hg exposure, CV-AAS: control 0.5 µg/L; medium-exposure 1.10 µg/L; high-exposure 1.20 µg/L (no SD reported).
  • Brazil (Bastos et al. 2018), n=106, FIMS/ICP-OES: Al 2307 ± 2300, Mn 119 ± 170, As 63 ± 100, Hg 10 ± 10, Pb 531 ± 400, Cd 74 ± 10.
  • Brazil (Alves Peixoto et al. 2019), n=156, ICP-MS: Ba 11.6 (range 0.6–88.2); Cu 618.3 (95.4–954.5); Fe 380 (110.5–3594); Mn 4.5 (1.6–22.2); Mo 9.3 (0.1–39.1); Se 12.6 (3.0–70.6); Sr 43.5 (14.9–71.1); Zn 2614.4 (422.8–17,727.2).
  • South Korea (Park et al. 2018), n=207, AMA-AAS: Hg 1.19 ± 1.24 (day-15 colostrum); 0.79 ± 0.73 (day-30 milk).
  • Saudi Arabia (Al-Saleh et al. 2013), n=155, AAS/GC-MS/AMA: Hg 1.191 ± 0.764.
  • Turkey (Nazlican et al. 2022), n=34, ICP-MS: Cr 8.249 ± 11.69, As 1.64 ± 1.85, Cd 0.37 ± 0.47, Hg 2.59 ± 3.47, Pb 12.12 ± 9.08.
  • Cyprus (Kunter et al. 2017), n=50, ELISA/ICP-MS: Pb 1.19 ± 1.53, Cd 0.45 ± 0.23, As 0.73 ± 0.58, Hg 0 ± 0.20.
  • Norway (Vollset et al. 2019), n=300, ICP-MS/MS: Hg 0.2 ± 0.17 µg/L; Cd 0.08 ± 0.10 µg/kg; Pb not detected. (Source Table 3 prints Hg in µg/L and Cd in µg/kg for this row — unit inconsistency preserved as published.)
  • Poland (Winiarska-Mieczan 2014), n=320, GFAAS: Cd 2.114 ± 2.112, Pb 6.331 ± 4.614, Cu 0.137 ± 0.092, Zn 1.623 ± 1.763.
  • Spain (Motas et al. 2021), n=50, ICP-MS: Al 34.3 ± 133.0, Zn 1402.6 ± 1742.7, As 0.9 ± 2.71, Cd 0.4 ± 1.6, Pb 5.2 ± 16.7, Hg 5.6 ± 12.4, Cr 16.1 ± 63.6, Mn 10.7 ± 63.6, Fe 679.1 ± 1387.3, Ni 25.3 ± 33.8, Cu 368.5 ± 301.0, Se 44.5 ± 49.5.
  • Spain (Freire et al. 2022), n=242, ICP-MS: As 1.49 (range 0.56–3.50), Hg 0.26 (0.05–1.17), Pb 0.14 (0.10–0.65); Cd not detected.

Selected infant-formula metals findings, Table 4 (as reported; mean ± SD or median:range; µg/kg unless noted):

  • Egypt (Ghuniem et al. 2020b), n=83, ICP-OES/GFAAS: Cd 5–17, Fe 32,000–86,870, Cu 0–8760, Mn 0–7110, Zn 22,460–87,300.
  • Egypt (Ghuniem et al. 2020a), n=28, ICP-OES + UN: Mn 3300, Co/Ni/Pb not detected, Sn 47,400, Cd 20, Cu 1000, Zn 11,400.
  • Egypt (Ibrahim et al. 2020), n=60, ICP-MS, milk-based vs milk-cereal-based: milk-based Pb 424 ± 6, As 205 ± 3, Cd 14 ± 0.1, Hg 298 ± 7, Al 464 ± 29; milk-cereal-based Pb 145 ± 4, As 214 ± 8, Cd 14 ± 0.1, Hg 296 ± 14, Al 352 ± 9.
  • Nigeria (Igweze et al. 2019), n=26, AAS, milk-based vs cereal-based vs cereal-mix: milk-based Fe 4080 ± 1950, Zn 6710 ± 2100, Mn 150 ± 90, Cr 610 ± 700, Co 120 ± 320; cereal-based Fe 3710 ± 1090, Zn 6110 ± 1450, Mn 90 ± 60, Cr 360 ± 620, Co 10 ± 20; cereal-mix Fe 4490 ± 1560, Zn 7140 ± 2560, Mn 100 ± 80, Cr 400 ± 360, Co 10 ± 10.
  • Nigeria (Igweze et al. 2020a), n=26, AAS: Al 410–2470, As 20–1560, Hg 0–50.
  • Nigeria (Igweze et al. 2020b), n=26, AAS, by formula type: milk-based Pb 610–3500, Cd 10–550; cereal-based Pb 290–1950, Cd 20–370; cereal-mix Pb 470–2340, Cd 1–460.
  • Brazil (de Paiva et al. 2019), n=3, GFAAS: Cd 2, Al 1000, Cu 410, Zn 39,600, Ni 50; Pb not detected.
  • Brazil (de Mendonça Pereira et al. 2020), n=140, ICP-MS: As 0.007–0.01, Cd 0.23, Pb 0.90, Al 50, Cr 37.75, Ni 25.47.
  • United States (Gardener et al. 2019), n=91, ICP-MS: Pb 9.72; Cd 5.60.
  • China (Su et al. 2020), n=93, ICP-MS: Cr 2.51–83.80, As 0.89–7.87, Cd 0.13–3.58, Pb 0.36–5.57.
  • India (Pacquette and Anumula 2016), n=10, ICP-MS: As 0.018, Cd 0.014, Hg 0.013, Pb 0.016.
  • Iran (Dehcheshmeh et al. 2021), n=80, GFAAS/ELISA: Pb 12.57, Cd 4.97.
  • Jordan (Tahboub et al. 2021), n=22, ICP-MS, 24-element profile reported in full; toxic-element subset As 4.7 ± 3.9, Cd 8.0 ± 16.3, Pb 64.9 ± 39.9.
  • Lebanon (Elaridi et al. 2021), n=78, ICP-MS: Pb 371 ± 581, Cd 255 ± 179, As 88.7 ± 71.0.
  • Pakistan (Saeed et al. 2021), n=10, FAAS: Fe 5230–7530, Zn 3200–5370, Cu 304.67–487.0, Pb 290–1050, Cd 280–980, Al 1480–2050.
  • Pakistan (Lutfullah et al. 2014), n=46, AAS: Ca 3081 ± 277, Mg 540 ± 206, Cu 1 ± 0.76, Zn 8.97 ± 2.35, Fe 4.33 ± 2.22, Mn 0.0318 ± 0.02, Pb 0.0091 ± 0.01, Cd 0.1507 ± 0.28, Cr 0.0007 ± 0.00, Ni 0.0146 ± 0.01.
  • Italy (Astolfi et al. 2021), n=19, ICP-MS, 40-element profile in powdered formulas; toxic-element subset Sn 25 ± 2, Cd reported under non-essentials, Pb reported under non-essentials (see Table 4 for full per-element values).
  • Malta (Vella and Attard 2019), n=6, MP-AES, by age band: 0–6 mo Cr 290 ± 50, Cu 3330 ± 240, Ni 760 ± 0.00, Fe 18,340 ± 2510, Mn 2130 ± 410, Zn 27,240 ± 2770; 6–12 mo Cr 240 ± 30, Cu 3370 ± 210, Ni 820 ± 60, Fe 18,870 ± 3060, Mn 2050 ± 210, Zn 33,000 ± 950; Hg not detected in either band.
  • Portugal (Pereira et al. 2020), n=26, GFAAS: Ni 40.2.
  • Spain (Gómez-Nieto et al. 2020), n=2, HR-CS-GFAAS: Cu 3850; Cd not detected.
  • Spain (Paz 2017), n=30, ICP-OES, full mineral profile; toxic-element subset Cr 130 ± 20, Mn 1000 ± 230, Mo 140 ± 10, Ni 70 ± 40, Sr 2470 ± 950, Cd 10 ± 0.00, Pb 70 ± 20.

Authors’ qualitative conclusion on metals (Section 3.1): more metals were detected in infant formula than in breast milk across Africa, Asia, and Europe; the Americas were the only region where the reverse held for the studies reviewed. The authors note that exceedances of EFSA-derived TDI-equivalent values were reported for at least one metal in studies from Morocco, Nigeria, Tanzania, Jordan, Pakistan, Italy, Malta, Spain, Egypt, Lebanon, Iran, India, China, Brazil, and the United States; for breast milk the most-exceedance metals across the reviewed studies were Zn, Cd, Cr, Pb, Ni, As, and Hg depending on cohort, and for infant formula the most-exceedance metals were Al, Mn, Fe, Cr, Co, As, Pb, Cd, and Ni.

Methods (brief)

Narrative review. Databases: PubMed/MEDLINE and Scopus. Search strings (per Section 2.1):

  • Breast milk: (breast milk OR breastfeeding OR human breast milk) AND (contaminants OR metals OR BPA OR heavy AND metals OR pesticides OR POPs OR nitrogenous OR phthalates OR mycotoxins), 2012–2022.
  • Infant formula: (infant AND formula OR infant AND formulas OR infant AND formulae OR infant AND food OR baby AND foods) AND (contaminants OR metals OR BPA OR heavy AND metals OR pesticides OR POPs OR nitrogenous OR phthalates OR mycotoxins), 2012–2022.

PubMed returned 2109 (breast milk) and 2605 (infant formula); Scopus returned 303 and 448. Records screening reduced these to 1022 and 984; full-text eligibility assessment to 354 and 258; final inclusion to 65 breast-milk studies and 73 infant-formula studies (Fig. 1 PRISMA-style flow diagram). The authors state that selection considered both abstract and full text and that additional studies were drawn in by cross-referencing.

Data treatment (Section 2.2): two parallel databases were assembled, each with six sections (location, sample size, contaminant/residue, methods, main outcomes, references). No meta-analysis, no quality appraisal, no PROSPERO registration mentioned; this is a narrative review of inclusion-then-tabulation form rather than a PRISMA-compliant systematic review. The constituent studies’ analytical methods (ICP-MS, ICP-OES, AAS, GFAAS, AMA, CV-AAS, AAS, ELISA, GC-MS, LC-MS, etc.) are recorded per row in Tables 3, 4, and 7–16; the review itself does not perform additional measurements.

Implications

  • Microbiome: the review notes infant gut microbiota colonization timing but does not study microbiome outcomes directly.

Update history

The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git.

CommitDateChangeDescription
b01ec52c312026-08-04major1 section added
3171d069e32026-08-02major1 section added
90a2f9a38e2026-07-30major1 section added and 1 removed
eaa8eeeedf2026-07-27major1 section added
af9c97a5092026-06-23major1 section added

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