Table 4.

Responsivity of breast milk contaminant levels in response to maternal diet

Ref	Participants Risk of bias	Study	Ethnicity	Breast milk collection timing	Effects on breast milk content
Observational studies
Castro, 2014	Lactating mothers Chile, 2–4 months PP Obs Fair quality 7	Participants from Arica (n 24) and southern Santiago (n 11) completed questionnaires on health status, food habits and breast-feeding practices. BM As, B, Cd, caesium, Ca, Fe, Pb, Li, Mn, Se, U, V and Zn measured	Not provided	BM collected during the morning	No difference in essential and toxic element levels between groups, except B (P < 0·001) and Li (P < 0·05), which were higher in Arica. Caesium was higher in Santiago samples (P < 0·05). Pb positively associated with Fe and Zn (r = 0·60, r = 0·61, respectively, both P < 0·05), but inversely associated with Ca (r = −0·61, P < 0·05). As associated with Fe (r = 0·6, P < 0·05), and B and Ca (r = 0·54, P < 0·05)
Dewailly, 1994	Lactating healthy Inuit women < 3 d PP Artic Quebec Obs Poor quality 2	Inuit (n 109) participants. Seven PCB and chlorinated pesticides determined in BM and compared with Quebec Caucasian women.	Inuit	Not provided	Mean levels of the different analysed PCB were 3–7 times higher in BM from Inuit v. Caucasian women. Seafood consumption was extremely high for Inuit women, at 300 g/d compared with 12 g/d for Caucasian women
Gundacker, 2002	Healthy lactating mothers < 1 month PP Austria Obs Good quality 8	Urban (n 59) and rural (n 47) participants completed questionnaire about dietary habits, smoking, living area and dental filings.	Not provided	Not provided	Low Hg and Pb concentrations were far below currently recommended safety limits (Hg: mean = 1·59 g/l, sd = 1·21 g/l, n 116; Pb: mean = 1·63 g/l, sd = 1·66 g/l, n 138). Hg was significantly associated with area of residence, prematurity, cereal consumption and vitamin supplementation, whereas for Pb it was area of residence, fish consumption and smoking, all P < 0·05
Leotsinidis, 2005	Healthy lactating mothers 3 d PP Greece Obs Fair quality 6	BM samples collected (n 180) to measure Cd and Pb at 3 and 14 d PP, FFQ	Not provided	Morning milk 2 h after previous breast-feeding	Mean (sd) values of colostrum samples: Cd, 0·190 (0·150) µg/l; Pb, 0·48 (0·60) µg/l. Higher BM lead in samples from urban areas, dietary habits seem to play a role in metal levels in human milk
Ursinyova, 2018	Healthy lactating mothers 6 weeks PP Slovakia Obs Good quality 7	n 142 participants asked about dietary habits, including frequency and amount of fish consumption per d	Not provided	Hand expression, no information on timing	Total Hg mean = 0·376 µg/l, sd = 0·475 µg/l, with no difference between fish and non-fish eaters. Negative association between BM total Hg and freshwater fish consumption (β = −0·193, P = 0·017)

Obs, observational study; PP, postpartum; BM, breast milk; PCB, polychlorinated biphenyls.