Chemical Contaminants in Raw and Pasteurized Human Milk

Biomonitoring of bisphenol A (BPA) and bisphenol analogues in human milk from South Africa and Canada using a modified QuEChERS extraction method

A sensitive modified QuEChERS extraction method was developed to assess the levels of free and conjugated bisphenols (BPs) in human milk collected between 2018 and 2019 from two regions of South Africa (the Limpopo Province Vhembe district, n = 194; Pretoria, n = 193) and Canada (Montreal, n = 207). Total BPA (free and conjugated) and BPS were the predominant bisphenols detected in samples from Vhembe and Pretoria, whereas total BPS was the predominant bisphenol detected in Montreal samples. The levels of total BPA in samples from Vhembe and Pretoria ranged between < MDL-18.61 and Collapse

Key Words

• Biomonitoring
• Bisphenols
• Canada
• Human milk
• Liquid chromatography–mass spectrometry
• South Africa

Collapse

MESH Headings

• Humans
• South Africa
• Biological Monitoring
• Milk, Human/chemistry
• Benzhydryl Compounds/analysis
• Canada
• Phenols

Collapse

Grants Collapse

Affiliation(s)

Zhi Hao Chi Department of Food Science and Agricultural Chemistry, McGill University, Montreal, QC, Canada
Lan Liu Department of Food Science and Agricultural Chemistry, McGill University, Montreal, QC, Canada
Jingyun Zheng Department of Food Science and Agricultural Chemistry, McGill University, Montreal, QC, Canada
Lei Tian Department of Food Science and Agricultural Chemistry, McGill University, Montreal, QC, Canada
Jonathan Chevrier Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montreal, QC, Canada
Riana Bornman University of Pretoria, Pretoria, South Africa
Muvhulawa Obida University of Pretoria, Pretoria, South Africa
Cynthia Gates Goodyer McGill University Health Centre Research Institute, Montreal, QC, Canada
Barbara F Hales Department of Pharmacology and Therapeutics, McGill University, Montreal, QC, Canada
Stéphane Bayen Department of Food Science and Agricultural Chemistry, McGill University, Montreal, QC, Canada.

Collapse

A systematic review of contaminants in donor human milk

Donor human milk (DHM) from a milk bank is the recommended feeding method for preterm infants when the mother's own milk (MOM) is not available. Despite this recommendation, information on the possible contamination of donor human milk and its impact on infant health outcomes is poorly characterised. The aim of this systematic review is to assess contaminants present in DHM samples that preterm and critically ill infants consume. The data sources used include PubMed, EMBASE, CINAHL and Web of Science. A search of the data sources targeting DHM and its potential contaminants yielded 426 publications. Two reviewers (S. T. and D. L.) conducted title/abstract screening through Covidence software, and predetermined inclusion/exclusion criteria yielded 26 manuscripts. Contaminant types (bacterial, chemical, fungal, viral) and study details (e.g., type of bacteria identified, study setting) were extracted from each included study during full-text review. Primary contaminants in donor human milk included bacterial species and environmental pollutants. We found that bacterial contaminants were identified in 100% of the papers in which bacterial contamination was sought (16 papers) and 61.5% of the full data set (26 papers), with the most frequently identified genera being Staphylococcus (e.g., Staphylococcus aureus and coagulase-negative Staphylococcus) and Bacillus (e.g., Bacillus cereus). Chemical pollutants were discovered in 100% of the papers in which chemical contamination was sought (eight papers) and 30.8% of the full data set (26 papers). The most frequently identified chemical pollutants included perfluoroalkyl substances (six papers), toxic metal (one paper) and caffeine (one paper). Viral and fungal contamination were identified in one paper each. Our results highlight the importance of establishing standardisation in assessing DHM contamination and future studies are needed to clarify the impact of DHM contaminants on health outcomes.

Update of the risk assessment of polybrominated diphenyl ethers (PBDEs) in food

The European Commission asked EFSA to update its 2011 risk assessment on polybrominated diphenyl ethers (PBDEs) in food, focusing on 10 congeners: BDE-28, -47, -49, -99, -100, -138, -153, -154, -183 and ‑209. The CONTAM Panel concluded that the neurodevelopmental effects on behaviour and reproductive/developmental effects are the critical effects in rodent studies. For four congeners (BDE-47, -99, -153, -209) the Panel derived Reference Points, i.e. benchmark doses and corresponding lower 95% confidence limits (BMDLs), for endpoint-specific benchmark responses. Since repeated exposure to PBDEs results in accumulation of these chemicals in the body, the Panel estimated the body burden at the BMDL in rodents, and the chronic intake that would lead to the same body burden in humans. For the remaining six congeners no studies were available to identify Reference Points. The Panel concluded that there is scientific basis for inclusion of all 10 congeners in a common assessment group and performed a combined risk assessment. The Panel concluded that the combined margin of exposure (MOET) approach was the most appropriate risk metric and applied a tiered approach to the risk characterisation. Over 84,000 analytical results for the 10 congeners in food were used to estimate the exposure across dietary surveys and age groups of the European population. The most important contributors to the chronic dietary Lower Bound exposure to PBDEs were meat and meat products and fish and seafood. Taking into account the uncertainties affecting the assessment, the Panel concluded that it is likely that current dietary exposure to PBDEs in the European population raises a health concern.

Has Regulatory Action Reduced Human Exposure to Flame Retardants?

Flame retardant (FR) exposure has been linked to several environmental and human health effects. Because of this, the production and use of several FRs are regulated globally. We reviewed the available records of polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDDs) in human breast milk from literature to evaluate the efficacy of regulation to reduce the exposure of FRs to humans. Two-hundred and seven studies were used for analyses to determine the spatial and temporal trends of FR exposure. North America consistently had the highest concentrations of PBDEs, while Asia and Oceania dominated HBCDD exposure. BDE-49 and -99 indicated decreasing temporal trends in most regions. BDE-153, with a longer half-life than the aforementioned isomers, typically exhibited a plateau in breast milk levels. No conclusive trend could be established for HBCDD, and insufficient information was available to determine a temporal trend for BDE-209. Breakpoint analyses indicated a significant decrease in BDE-47 and -99 in Europe around the time that regulation has been implemented, suggesting a positive effect of regulation on FR exposure. However, very few studies have been conducted globally (specifically in North America) after 2013, during the time when the most recent regulations have been implemented. This meta-analysis provides insight into global trends in human exposure to PBDEs and HBCDD, but the remaining uncertainty highlights the need for ongoing evaluation and monitoring, even after a compound group is regulated.

The State of Research and Weight of Evidence on the Epigenetic Effects of Bisphenol A

Bisphenol A (BPA) is a high-production-volume chemical with numerous industrial and consumer applications. BPA is extensively used in the manufacture of polycarbonate plastics and epoxy resins. The widespread utilities of BPA include its use as internal coating for food and beverage cans, bottles, and food-packaging materials, and as a building block for countless goods of common use. BPA can be released into the environment and enter the human body at any stage during its production, or in the process of manufacture, use, or disposal of materials made from this chemical. While the general population is predominantly exposed to BPA through contaminated food and drinking water, non-dietary exposures through the respiratory system, integumentary system, and vertical transmission, as well as other routes of exposure, also exist. BPA is often classified as an endocrine-disrupting chemical as it can act as a xenoestrogen. Exposure to BPA has been associated with developmental, reproductive, cardiovascular, neurological, metabolic, or immune effects, as well as oncogenic effects. BPA can disrupt the synthesis or clearance of hormones by binding and interfering with biological receptors. BPA can also interact with key transcription factors to modulate regulation of gene expression. Over the past 17 years, an epigenetic mechanism of action for BPA has emerged. This article summarizes the current state of research on the epigenetic effects of BPA by analyzing the findings from various studies in model systems and human populations. It evaluates the weight of evidence on the ability of BPA to alter the epigenome, while also discussing the direction of future research.

Postnatal exposure to organic pollutants in maternal milk in north-western Spain

Evaluation of postnatal exposure to organic pollutants is especially important for suckling infants during breastfeeding, a crucial perinatal growth period when organs and hormonal systems develop. We determined levels of 60 pollutants, including organochlorine pesticides (OCPs), organophosphorus pesticides (OPPs), pyrethroids (PYRs), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and polybrominated diphenyl ethers (PBDEs), in 81 breast milk samples from breastfeeding mothers from Santiago de Compostela (north-western Spain). For most detected organic pollutants, levels were correlated with the season of milk sampling, maternal age at delivery, and place of residence. Dietary consumption habits (eggs, molluscs, and vegetable oils) were also correlated with OCP, OPP, PCB, PBDE and PYR levels. We also assessed the risk to infant health of exposure to organic pollutants in breast milk. PAHs, OCPs, OPPs, and PYRs accounted for almost 95% of the targeted organic pollutants in the samples analysed.

The Results of Different Heating Temperatures on Activities of Bioactive Proteins in Human Milk

BACKGROUND

The most utilized pasteurization method in donor human milk banks is Holder pasteurization (heating 62.5 °C for 30 min). However, many bioactive proteins are heat sensitive and are inactivated.

RESEARCH AIM

To determine the results of a range of heating regimes on the activities of xanthine oxidase, lactoperoxidase and lysozyme, the concentrations of immunoglobulin A and lactoferrin, as well as bacterial inactivation.

METHOD

This prospective, cross-sectional, intervention study was designed to measure the influence of heating temperatures on bioactive components in donor human milk. Milk samples were processed at 40, 50, 55, 62.5, 75, 127 °C and the activities of the enzymes, and the concentration of immune proteins, were measured.

RESULTS

No bacterial colonies were detectable, using standard culture methods, after heating above 50 ºC. All proteins studied retained over 60% concentrations or activities when the pasteurization temperature was 50 ºC or lower, while their concentrations or activities were lost at higher temperatures. For lactoferrin, the residual concentration was above 80% when heating temperature was under 55 °C, while only 20% remained after Holder pasteurization. Both xanthine oxidase and lactoperoxidase had little residual activity when temperatures were above Holder pasteurization. Lysozyme retained a greater proportion of residual activity than other proteins, following heating at all temperatures.

CONCLUSIONS

The concentrations or activities of immune proteins and bioactive enzymes decreased when heated above 50 °C. The results of this study can be used to design temperature control guidance during alternative methods of pasteurization.

Chlorpyrifos Occurrence and Toxicological Risk Assessment: A Review

Chlorpyrifos (CPF) was the most frequently used pesticide in food production in the European Union (EU) until 2020. Unfortunately, this compound is still being applied in other parts of the world. National monitoring of pesticides conducted in various countries indicates the presence of CPF in soil, food, and water, which may have toxic effects on consumers, farmers, and animal health. In addition, CPF may influence changes in the population of fungi, bacteria, and actinomycete in soil and can inhibit nitrogen mineralization. The mechanisms of CPF activity are based on the inhibition of acetylcholinesterase (AChE) activity. This compound also exhibits reproductive toxicity, neurotoxicity, and genotoxicity. The problem seems to be the discrepancy between the actual observations and the final conclusions drawn for the substance's approval in reports presenting the toxic impact of CPF on human health. Therefore, this influence is still a current and important issue that requires continuous monitoring despite its withdrawal from the market in the EU. This review traces the scientific reports describing the effects of CPF resulting in changes occurring in both the environment and at the cellular and tissue level in humans and animals. It also provides an insight into the hazards and risks to human health in food consumer products in which CPF has been detected.

Mixture of environmental pollutants in breast milk from a Spanish cohort of nursing mothers

Breastfeeding is one of the most effective ways to ensure child health and survival, with several benefits for both the infants and their mothers. However, breast milk can contain environmental pollutants with endocrine disruption capacity, neurotoxicity and/or potential to alter microbiota. Monitoring breast milk provides information on the current chemical exposure of breastfed infants and, in addition, on the current and historical exposure of nursing mothers. In this study, the levels of a wide range of pollutants were measured in breast milk of Spanish nursing mothers. Target chemicals were dichlorodiphenyltrichloroethane (DDT), dichlorodiphenyldichloroethylene (DDE), hexachlorobenzene (HCB), oxy-chlordane, polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), per- and poly-fluoroalkyl substances (PFASs) (including perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA)), chlorpyrifos, bisphenol A (BPA), tetrabromobisphenol A (TBBPA), and a number of toxic and essential elements. Traces of most chemicals were found. A correlation between the levels of some persistent organic pollutants (POPs) and maternal characteristics (age and body mass index) was observed, while smoking was associated to higher concentrations of some toxic elements. Higher levels of PCBs were detected in samples from Spanish primiparous mothers compared to non-Spanish multiparous women. Breast milk from low-income mothers showed higher content of DDT and DDE than high-income mothers. Although breastfeeding is clearly beneficial for babies, the exposure to this mixture of hazardous substances, as well as their interaction and combined effects must not be disregarded.

Polychlorinated environmental toxicants affect sphingolipid metabolism during neurogenesis in vitro

Sphingolipids (SLs) are important signaling molecules and functional components of cellular membranes. Although SLs are known as crucial regulators of neural cell physiology and differentiation, modulations of SLs by environmental neurotoxicants in neural cells and their neuronal progeny have not yet been explored. In this study, we used in vitro models of differentiated neuron-like cells, which were repeatedly exposed during differentiation to model environmental toxicants, and we analyzed changes in sphingolipidome, cellular morphology and gene expression related to SL metabolism or neuronal differentiation. We compared these data with the results obtained in undifferentiated neural cells with progenitor-like features. As model polychlorinated organic pollutants, we used 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 3,3'-dichlorobiphenyl (PCB11) and 2,2',4,4',5,5'-hexachlorobiphenyl (PCB153). PCB153 revealed itself as the most prominent deregulator of SL metabolism and as potent toxicant during early phases of in vitro neurogenesis. TCDD exerted only minor changes in the levels of analysed lipid species, however, it significantly changed the rate of pro-neuronal differentiation and deregulated expression of neuronal markers during neurogenesis. PCB11 acted as a potent disruptor of in vitro neurogenesis, which induced significant alterations in SL metabolism and cellular morphology in both differentiated neuron-like models (differentiated NE4C and NG108-15 cells). We identified ceramide-1-phosphate, lactosylceramides and several glycosphingolipids to be the most sensitive SL species to exposure to polychlorinated pollutants. Additionally, we identified deregulation of several genes related to SL metabolism, which may be explored in future as potential markers of developmental neurotoxicity.

Combining in vitro assays and mathematical modelling to study developmental neurotoxicity induced by chemical mixtures

Prenatal and postnatal co-exposure to multiple chemicals at the same time may have deleterious effects on the developing nervous system. We previously showed that chemicals acting through similar mode of action (MoA) and grouped based on perturbation of brain derived neurotrophic factor (BDNF), induced greater neurotoxic effects on human induced pluripotent stem cell (hiPSC)-derived neurons and astrocytes compared to chemicals with dissimilar MoA. Here we assessed the effects of repeated dose (14 days) treatments with mixtures containing the six chemicals tested in our previous study (Bisphenol A, Chlorpyrifos, Lead(II) chloride, Methylmercury chloride, PCB138 and Valproic acid) along with 2,2'4,4'-tetrabromodiphenyl ether (BDE47), Ethanol, Vinclozolin and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)), on hiPSC-derived neural stem cells undergoing differentiation toward mixed neurons/astrocytes up to 21 days. Similar MoA chemicals in mixtures caused an increase of BDNF levels and neurite outgrowth, and a decrease of synapse formation, which led to inhibition of electrical activity. Perturbations of these endpoints are described as common key events in adverse outcome pathways (AOPs) specific for DNT. When compared with mixtures tested in our previous study, adding similarly acting chemicals (BDE47 and EtOH) to the mixture resulted in a stronger downregulation of synapses. A synergistic effect on some synaptogenesis-related features (PSD95 in particular) was hypothesized upon treatment with tested mixtures, as indicated by mathematical modelling. Our findings confirm that the use of human iPSC-derived mixed neuronal/glial models applied to a battery of in vitro assays anchored to key events in DNT AOP networks, combined with mathematical modelling, is a suitable testing strategy to assess in vitro DNT induced by chemical mixtures.

Developmental Exposure to PCB153 (2,2',4,4',5,5'-Hexachlorobiphenyl) Alters Circadian Rhythms and the Expression of Clock and Metabolic Genes

Polychlorinated biphenyls (PCBs) are highly persistent and ubiquitously distributed environmental pollutants. Based on their chemical structure, PCBs are classified into non-ortho-substituted and ortho-substituted congeners. Non-ortho-substituted PCBs are structurally similar to dioxin and their toxic effects and mode of action are well-established. In contrast, very little is known about the effects of ortho-substituted PCBs, particularly, during early development. The objective of this study is to investigate the effects of exposure to an environmentally prominent ortho-substituted PCB (2,2',4,4',5,5'-hexachlorobiphenyl; PCB153) on zebrafish embryos. We exposed zebrafish embryos to 3 different concentrations of PCB153 starting from 4 to 120 hours post-fertilization (hpf). We quantified gross morphological changes, behavioral phenotypes, gene expression changes, and circadian behavior in the larvae. There were no developmental defects during the exposure period, but starting at 7 dpf, we observed spinal deformity in the 10 μM PCB153 treated group. A total of 633, 2227, and 3378 differentially expressed genes were observed in 0.1 μM (0.036 μg/ml), 1 μM (0.36 μg/ml), and 10 μM (3.6 μg/ml) PCB153-treated embryos, respectively. Of these, 301 genes were common to all treatment groups. KEGG pathway analysis revealed enrichment of genes related to circadian rhythm, FoxO signaling, and insulin resistance pathways. Behavioral analysis revealed that PCB153 exposure significantly alters circadian behavior. Disruption of circadian rhythms has been associated with the development of metabolic and neurological diseases. Thus, understanding the mechanisms of action of environmental chemicals in disrupting metabolism and other physiological processes is essential.

Antioxidative Molecules in Human Milk and Environmental Contaminants

Breastfeeding provides overall beneficial health to the mother-child dyad and is universally recognized as the preferred feeding mode for infants up to 6-months and beyond. Human milk provides immuno-protection and supplies nutrients and bioactive compounds whose concentrations vary with lactation stage. Environmental and dietary factors potentially lead to excessive chemical exposure in critical windows of development such as neonatal life, including lactation. This review discusses current knowledge on these environmental and dietary contaminants and summarizes the known effects of these chemicals in human milk, taking into account the protective presence of antioxidative molecules. Particular attention is given to short- and long-term effects of these contaminants, considering their role as endocrine disruptors and potential epigenetic modulators. Finally, we identify knowledge gaps and indicate potential future research directions.

Occurrence of bisphenol A in the milk chain: A monitoring model for risk assessment at a dairy company

Bisphenol A (BPA) as a chemical hazard may enter the milk chain during primary production at the farm and, successively, during milk processing at a dairy company. To identify the potential pathways that play a role in the occurrence of BPA, a monitoring model for risk assessment based on the identification of the hazards at each stage of milk processing was investigated. Milk samples were analyzed using liquid chromatography with fluorescence detection. Quantifiable levels were detected in samples obtained from the raw milk storage tank, pasteurized milk from the storage tank, and packaged milk. The highest BPA contamination levels were detected in raw milk from the storage tank (mean 0.265 µg/L). Despite the fact that dietary exposure levels were below the temporary daily intake, BPA may have adverse effects, particularly for vulnerable population groups. New monitoring programs involving each stage of milk processing should therefore be applied.

ExpoKids: An R-based tool for characterizing aggregate chemical exposure during childhood

BACKGROUND

Aggregate exposure, the combined exposures to a single chemical from all pathways, is a critical children's health issue.

OBJECTIVE

The primary objective is to develop a tool to illustrate potential differences in aggregate exposure at various childhood lifestages and the adult lifestage.

METHODS

We developed ExpoKids (an R-based tool) using oral exposure estimates across lifestages generated by US EPA's Exposure Factors Interactive Resource for Scenarios Tool (ExpoFIRST).

RESULTS

ExpoKids is applied to illustrate aggregate oral exposure, for ten media, as average daily doses (ADD) and lifetime average daily doses (LADD) in five graphs organized across seven postnatal childhood lifestages and the adult lifestage. This data visualization tool conveys ExpoFIRST findings, from available exposure data, to highlight the relative contributions of media and lifestages to chemical exposure. To evaluate the effectiveness of ExpoKids, three chemical case examples (di[2-ethylhexyl] phthalate [DEHP], manganese, and endosulfan) were explored. Data available from the published literature and databases for each case example were used to explore research questions regarding media and lifestage contributions to aggregate exposure.

SIGNIFICANCE

These illustrative case examples demonstrate ExpoKids' versatile application to explore a diverse set of children's health risk assessment and management questions by visually depicting specific media and lifestage contributions to aggregate exposure.

Integrating biokinetics and in vitro studies to evaluate developmental neurotoxicity induced by chlorpyrifos in human iPSC-derived neural stem cells undergoing differentiation towards neuronal and glial cells

•

Human iPSC-derived NSCs undergoing differentiation possess some metabolic competence.

•

CPF entered the cells and was biotrasformed into its two main metabolites (CPFO and TCP).

•

After repeated exposure, very limited bioaccumulation of CPF was observed.

•

Treatment with CPF decreased neurite outgrowth, synapse number and electrical activity.

•

Treatment with CPF increased BDNF levels and the percentage of astrocytes.

For some complex toxicological endpoints, chemical safety assessment has conventionally relied on animal testing. Apart from the ethical issues, also scientific considerations have been raised concerning the traditional approach, highlighting the importance for considering real life exposure scenario. Implementation of flexible testing strategies, integrating multiple sources of information, including in vitro reliable test methods and in vitro biokinetics, would enhance the relevance of the obtained results. Such an approach could be pivotal in the evaluation of developmental neurotoxicity (DNT), especially when applied to human cell-based models, mimicking key neurodevelopmental processes, relevant to human brain development.

Here, we integrated the kinetic behaviour with the toxicodynamic alterations of chlorpyrifos (CPF), such as in vitro endpoints specific for DNT evaluation, after repeated exposure during differentiation of human neural stem cells into a mixed culture of neurons and astrocytes. The upregulation of some cytochrome P450 and glutathione S-transferase genes during neuronal differentiation and the formation of the two major CPF metabolites (due to bioactivation and detoxification) supported the metabolic competence of the used in vitro model. The alterations in the number of synapses, neurite outgrowth, brain derived neurotrophic factor, the proportion of neurons and astrocytes, as well as spontaneous electrical activity correlated well with the CPF ability to enter the cells and be bioactivated to CPF-oxon. Overall, our results confirm that combining in vitro biokinetics and assays to evaluate effects on neurodevelopmental endpoints in human cells should be regarded as a key strategy for a quantitative characterization of DNT effects.

Polybrominated diphenyl ethers and novel brominated flame retardants in human milk from the general population in Beijing, China: Occurrence, temporal trends, nursing infants' exposure and risk assessment

The levels of eight polybrominated diphenyl ether (PBDE) congeners, and six novel brominated flame retardants (NBFRs) were determined in human milk collected from Beijing, China in 2014. The tested 111 samples were collected from 37 mothers, and each donor provided one milk sample per month for 3 months after childbirth. Levels of ∑PBDEs (total tri- to deca-BDEs) were in the range of 0.288 to 22.2 ng g^-1 lw (lipid weight). BDE-209, with a median level of 2.2 ng g^-1 lw, was the predominant congener. Decabromodiphenyl ethane (DBDPE), as an NBFR and a substitute for deca-BDE, was found to be the most abundant BFR in all tested human milk (median:5.96 ng g^-1 lw). This result might suggest that the predominantly consumed BFRs in China have changed from PBDEs to PBDE substitutes. Additionally, a comparison to our previous studies conducted in 2005 and 2011 revealed that levels of tri- to hepta-BDEs showed significant reduction from 2005 to 2014, whereas levels of BDE-209 showed no significant variation from 2011 to 2014. Temporal trends of BFR levels over the three months of lactation were also investigated, and no significant changes were found in concentration with time over the three months lactation. For nursing infants up to 6 months old, the median lower bound of daily BFR intakes via human milk ingestion ranged from zero for 2,3-dibromopropyl-2,4,6-tribromophenyl ether (DPTE) and 1,2-bis(2,4,6-tribromophenoxy)-ethane (BTBPE) to 18.7 ng kg^-1 bodyweight day^-1 for DBDPE. Although the daily dietary BFR intake for nursing infants was found to be much higher than that for adults, the risk assessment evaluated by the margin of exposure (MOE) approach revealed that dietary BFR intake for nursing infants was unlikely to pose significant health risks.