Overview
This Scientific Reports study measured six essential elements and six potentially toxic elements in breast milk from 100 lactating women in western Iran. The source reports higher arsenic, cadmium, mercury, and lead concentrations in active or passive smoke-exposure groups than in non-smoker controls. It is routeable as human-milk occurrence and infant-exposure context, not as commercial infant-food evidence.
Key numbers
Table 2 reports median (Q1-Q3) concentrations in ug/L:
| Element | Passive smokers | Active smokers | Non-smokers | Total | Group-test p value |
|---|---|---|---|---|---|
| total arsenic (tAs) | 1.48 (1.09-2.69) | 2.96 (1.19-4.34) | 0.71 (0.12-1.80) | 1.19 (0.36-3.10) | <0.001 |
| cadmium (Cd) | 0.88 (0.76-1.14) | 0.86 (0.68-1.16) | 0.60 (0.26-0.77) | 0.69 (0.37-1.1) | <0.001 |
| chromium (Cr) | 30.68 (24.06-44.74) | 41.06 (31.85-45.46) | 31.092 (20.58-53.30) | 34.29 (22.44-48.43) | 0.440 |
| total mercury (tHg) | 0.34 (0.24-0.59) | 0.44 (0.27-0.44) | 0.14 (0.11-0.14) | 0.14 (0.14-0.45) | <0.001 |
| nickel (Ni) | 18.31 (13.32-22.97) | 18.77 (15.09-22.25) | 15.36 (11.30-22.42) | 17.99 (11.87-22.46) | 0.586 |
| lead (Pb) | 14.09 (9.73-17.51) | 14.24 (10.83-17.86) | 8.99 (7.36-11.80) | 11.01 (7.80-14.51) | 0.0004 |
For essential elements, Table 2 reports total medians of Mg 17.15 ug/L, Mn 4.75 ug/L, Fe 390.15 ug/L, Co 0.5 ug/L, Cu 20.85 ug/L, and Zn 427.5 ug/L.
Post-hoc Dunn tests found significant differences for arsenic (As) between non-smokers and active smokers; cadmium (Cd) between non-smokers and both passive and active smokers; mercury (Hg) between non-smokers and both passive and active smokers; and lead (Pb) between non-smokers and both active and passive smokers.
Methods (brief)
The cross-sectional study collected 5-10 mL morning milk samples from lactating women in Kermanshah, Iran, from September to December 2021. Milk was digested with nitric acid and hydrogen peroxide, then analyzed by ICP-MS using an Agilent 7900 for Mg, Mn, Fe, Co, Cu, Zn, As, Cd, chromium (Cr), Hg, nickel (Ni), and Pb. The paper reports recovery rates of 96-102% across measured elements.
Implications
The source supports human-milk occurrence evidence and exposure-factor context for smoking and second-hand smoke. Its As and Hg results are total/source-reported values and should not be used as inorganic arsenic or methylmercury substitutes. The study should remain separated from infant-formula or commercial infant-food benchmark rows.
Related evidence
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