This study measured Pb, Cd, tHg, and tAs in breast milk from 209 Korean lactating mothers, assessed potential infant health risks using estimated daily intake (EDI) and hazard quotient (HQ), and identified maternal dietary factors associated with heavy metal concentrations via multiple linear regression. Cadmium was the most frequently detected metal (99% of samples), followed by Hg (97%), As (89%), and Pb (79%). The authors employed age-specific infant body weight and milk consumption to refine the exposure model beyond single representative values. Arsenic was identified as the largest contributor to potential health risk. Dietary associations: Pb with legume and seaweed consumption; Cd with vegetables and seaweed; tHg with sugar intake; tAs with meat intake.
Key numbers
All concentrations in µg/L (breast milk). n = 209. Analyzed by ICP-MS. LODs: Pb 0.017 µg/L, Cd 0.030 µg/L, Hg 0.047 µg/L, As 0.054 µg/L.
Concentrations (from available extracted data):
- Cd: GM and median = 0.13 µg/L; detection rate = 99%
- Hg: GM = 0.18 µg/L; range = 0.05–1.28 µg/L; detection rate = 97%
- tAs: GM = 1.16 µg/L; range = 0.08–9.48 µg/L; detection rate = 89%
- Pb: GM = 0.11 µg/L; range = 0.02–1.49 µg/L; detection rate = 79%
EDI (µg/kg body weight/day, median, GM, range):
- Pb: 0.017, 0.016 (SD 0.030), range 0.002–0.150
- Hg: 0.021, 0.019 (SD 0.015), range 0.004–0.070
- Cd: 0.014, 0.014 (SD 0.012), range 0.003–0.051
- tAs: full values in paper Tables 3/S3 (not fully extracted; As was the largest HQ contributor)
Dietary associations (multiple linear regression):
- Pb ↑: higher legume and seaweed consumption
- Cd ↑: higher vegetable and seaweed consumption
- tHg ↑: higher sugar intake (unusual — mechanism not explained; possibly proxy for processed food consumption)
- tAs ↑: higher meat intake (possibly reflecting organic As from animal feed additives)
Health risk: As had the highest HQ among the four metals; HQ for As exceeded 1.0 in some infants. All other metals had HQ < 1 at median EDI.
Methods (brief)
ICP-MS (not specified by model). Sample collection: trained nurses used hand-pressing method to minimize contamination; 20 mL breast milk into pre-cleaned glass bottles, stored at −70°C. Sample prep: ~0.1–0.2 g diluted with alkaline solution. LODs: Pb 0.017 µg/L, Cd 0.030 µg/L, Hg 0.047 µg/L, As 0.054 µg/L. Linearity: R² > 0.99 for all. Dietary assessment: 24-hour recall method administered by trained nurses. Ethics: approved by IRB of Kyung Hee University (KHSIRB-24-218(NA) and KHSIRB-21-598(NA)).
Speciation note: tAs reported; no distinction between inorganic and organic As species. tHg reported; no MeHg speciation. The tAs figures include organic arsenicals from seafood and possibly feed additives in meat, which means the toxicological significance is different from iAs-dominated exposure scenarios.
Implications
Certification: This is the largest and most methodologically rigorous recent study of heavy metals in Korean breast milk, with a nationally representative prospective cohort design. The As GM of 1.16 µg/L and detection rate of 89% make tAs the primary concern. The association of tAs with meat intake (rather than rice or seafood) is unexpected and warrants attention — possible explanation is residual organoarsenic compounds from animal feed additives.
Courses: The dietary association data (legumes → Pb; seaweed → Pb and Cd; vegetables → Cd) provide practical nutritional guidance for lactating mothers trying to reduce heavy metal transfer to infants. The tHg → sugar intake association is unusual and should be flagged as a correlation-not-causation finding.
App: Breast milk is not in the app’s ingredient-list model. This source informs the health effects sections for breastmilk and arsenic.
Microbiome: High tAs exposure to the infant gut during the 0–6 month colonization window, combined with Cd and Pb, has implications for gut microbiome development; cross-link when relevant pages exist.