(P27-070-25) Contaminant Exposure During Pregnancy and Lactation and Contaminant Concentrations in Human Milk: A Systematic Review

Objectives: The US Food and Drug Administration aims to reduce contaminant exposure from foods, with special interest for infants and children. Our objective was to assess relationships between arsenic, cadmium, lead, mercury, and per- and polyfluoroalkyl substances (PFAS) exposure during pregnancy and lactation and respective concentrations in human milk (HM).

Methods: The protocol was informed by a technical expert panel and the search strategy was developed by two evidence synthesis information specialists. Embase, CINAHL, CAB Abstracts, MEDLINE, and CENTRAL databases were searched for peer-reviewed articles published in English through September 3, 2024 from countries rated ‘high’ or ‘very high’ on the Human Development Index that assessed relationships between contaminant exposure during pregnancy or lactation and contaminant concentrations in HM. Articles were screened at title/abstract and full text level by two reviewers independently. Data were synthesized narratively. Sample collection and analytic methods were reviewed by technical experts; data were omitted if methods were deemed inappropriate or unreliable to assess exposure. ROBINS-E and GRADE were used to assess risk of bias and certainty of evidence, respectively.

Results: From 2705 records identified, 40 articles from 38 studies (13 prospective cohort, 25 cross-sectional) conducted in 22 countries were included (arsenic n=3 articles, cadmium n=5, lead n=17, mercury n=14, PFAS n=5). Higher exposure to lead and mercury during pregnancy and lactation correlated with higher concentrations of these contaminants in HM, respectively. The certainty of evidence was very low due to variability in the strength and statistical significance of correlation coefficients as well as the high risk of bias in most studies. Additionally, higher exposure to PFOS and PFOA during pregnancy and lactation correlated with higher concentrations of these contaminants in HM, respectively. Certainty was moderate for PFOA and PFOS due to strong and consistent correlations reported across studies. The evidence for cadmium or arsenic was limited and inconclusive.

Conclusions: Higher exposure to lead, mercury, PFOA, and PFOS during pregnancy or lactation correlated with concentrations of these contaminants in HM.

Funding Sources: US Food and Drug Administration