Breastmilk (Human Milk)
Breastmilk is the infant exposure route this wiki tracks alongside infant formula. It is not a manufactured ingredient and does not appear in any product-category page, but it is the comparator against which formula-fed infant exposure is measured and the source of evidence behind WHO and AAP feeding guidance. The page exists so that cohort studies, systematic reviews, and agency tox profiles addressing breastmilk concentrations of Pb, Cd, As species, Hg species, and Al can route here cleanly.
Breastmilk concentrations of heavy metals are driven primarily by maternal exposure history (diet, drinking water, occupational, geographic) and by the partitioning behavior of each metal across the mammary epithelial barrier. Lead and arsenic partition relatively poorly into breastmilk; mercury (especially MeHg) partitions more readily but is also bound by breast tissue and shed via hair. The literature is unanimous that breastmilk concentrations are typically lower than formula concentrations for Pb and Cd when reconstituted formula is compared in matched-population studies; the comparison for iAs depends heavily on the formula’s water source and base ingredient.
This page is the structural anchor for breastmilk-as-exposure-route claims; the vulnerable-population framing in vulnerable-populations and the infant-feeding guidance comparison on infant-formula-powder-non-soy cite this page.
Routing
Comparisons with formula route through the infant-formula product pages. Mechanism and toxicokinetic claims about lactational transfer live in health and microbiome.
Contamination Profile State
All ten contamination_profile sub-blocks are pending. Population-typical concentrations from breastmilk vary by region and exposure regime more than for any food matrix; values will populate as the contributing source pages are synthesized per Part 9.
Sources
Auto-generated from source-page frontmatter. The “Used on this page for” column is populated by the orchestrator’s POPULATE-SOURCE-LEGEND action; pending entries appear as *[awaiting synthesis]*.
| # | Citation | Year | Type | Used on this page for |
|---|---|---|---|---|
| 1 | Thoerig et al. 2025. Assessment of arsenic, cadmium, lead, mercury, and per- and polyfluoroalkyl substances concentrations in human milk and infant formula in the United States: a systematic review, American Journal of Clinical Nutrition, Vol. 122, pp. 1006-1026 | 2025 | Peer-reviewed | Systematic review of U.S. evidence on As, Cd, Pb, Hg, and PFAS concentrations in human milk vs infant formula; documents generally lower human-milk concentrations than reconstituted formula for these elements |
| 2 | Pikounis et al. 2024. Urinary biomarkers of exposure to toxic and essential elements: A comparison of infants fed with human milk or formula, Environmental Epidemiology | 2024 | Peer-reviewed | U.S. infant cohort study comparing urinary biomarkers for iAs, Pb, Cd, Hg, and Mn in breastfed vs formula-fed infants; formula-fed infants showed higher As and Mn biomarker levels |
| 3 | Ocaña et al. 2024. Metal availability shapes early life microbial ecology and community succession, mBio 15(7):e00854-24 | 2024 | Peer-reviewed | Demonstrates that formula-fed infants have higher gastrointestinal Zn and Mn than breastfed infants, with measurable effects on early gut microbiome community assembly |
| 4 | Carignan et al. 2016. Contribution of breast milk and formula to arsenic exposure during the first year of life in a U.S. prospective cohort, Journal of Exposure Science and Environmental Epidemiology, Vol. 26, No. 5, pp. 452-457 | 2016 | Peer-reviewed | Prospective U.S. cohort quantifying iAs/tAs exposure from human milk vs formula across the first year of life; feeding mode and rice-cereal introduction are primary exposure determinants |
| 5 | Carignan et al. 2015. Estimated Exposure to Arsenic in Breastfed and Formula-Fed Infants in a United States Cohort, Environmental Health Perspectives, Vol. 123, No. 5, pp. 500-506 | 2015 | Peer-reviewed | U.S. infant cohort study using urinary As biomarkers to compare arsenic exposure in breastfed vs formula-fed infants; formula-fed infants had higher urinary As levels, establishing feeding mode as a key determinant |
| 6 | ATSDR 2008. Toxicological Profile for Aluminum, U.S. Department of Health and Human Services, Public Health Service, Agency for Toxic Substances and Disease Registry | 2008 | Government report | ATSDR Al toxicological profile covering dietary exposure routes including human milk and infant formula; includes Al MRL derivation and infant-exposure context |