Trace element composition of plasma and breast milk of well-nourished women

Accumulation characteristics of metals in human breast milk and association with dietary intake in northeastern China

The trace elements present in breast milk play a vital role in the growth and development of infants. Nevertheless, numerous studies have reported the presence of toxic metal contamination in breast milk from various countries and regions, which poses potential risks to breastfed infants. This article aimed to investigate the characteristics of trace elements in breast milk and explore the relationship between breast milk and diet in Dalian, a coastal city in northeastern China. Breast milk samples and representative local food samples were collected from Dalian for research. The results revealed that 57 % of breast milk samples significantly exceeded the WHO safety limit (0.6 μg/L) for arsenic, with a measured mean value of 0.96 μg/L. Moreover, the levels of chromium (mean value: 2.63 μg/L) in 34 % of breast milk samples exceed the WHO recommended safety level (chromium: 1.5 μg/L). Aquatic foods accounted for 60 % to 90 % of the total intake of arsenic, cadmium, vanadium, mercury, and lead. The Spearman correlation analysis demonstrated strong positive correlations among breast milk metal elements, including copper-zinc (r = 0.68) and nickel‑chromium (r = 0.89). Furthermore, the food-to-milk accumulation factors (FMAF) of strontium, nickel, arsenic, vanadium, cadmium, and mercury were relatively low (median values <0.005). While the FMAF values for chromium and lead were higher, with median values of 0.038 and 0.07, respectively. The results indicated potential risks of the toxic metal arsenic in breast milk from Dalian, China for breastfed infants. Therefore, continuous monitoring of breast milk for toxic metals and foodborne contamination is necessary.

Aluminum Concentrations in Breast Milk Samples Obtained from Breastfeeding Women from a Resource-Limited Country: A Study of the Predicting Factors

This study assessed aluminum concentrations in breast milk samples obtained from breastfeeding women in resource-limited countries, estimated daily intake of aluminum by breastfed infants, and identified predictors of higher breast milk aluminum concentrations. A descriptive analytical approach was used in this multicenter study. Breastfeeding women were recruited from different maternity health clinics in Palestine. Aluminum concentrations in 246 breast milk samples were determined using an inductively coupled plasma-mass spectrometric method. The mean breast milk aluminum concentration was 2.1 ± 1.5 mg/L. The mean estimated daily intake of aluminum by infants was 0.37 ± 0.26 mg/kg body weight/day. Multiple linear regression showed that breast milk aluminum concentrations were predicted by living in urban areas, closer to industrial areas, waste disposals, frequent use of deodorants, and less frequent use of vitamins. Breast milk aluminum levels among Palestinian breastfeeding women were comparable to those previously determined in occupationally unexposed women.

Concentrations and determinants of lead, mercury, cadmium, and arsenic in pooled donor breast milk in Spain

AIM

To measure concentrations of lead (Pb), mercury (Hg), cadmium (Cd), and arsenic (As) in longitudinally collected donor breast milk samples and to determine associated factors.

METHODS

Pb, Hg, Cd, and As concentrations were measured in 242 pooled breast milk samples from 83 donors to a Human Milk Bank in Spain, in 2015-2018, determining their association with the donors' sociodemographic profile, dietary and lifestyle habits, and post-partum time, among other factors, and with the nutritional characteristics of samples. Mixed-effect linear regression was used to identify predictors of Hg and As concentrations in breast milk and mixed-effect logistic regression to identify predictors of the presence of Pb and Cd.

RESULTS

As was the element most frequently detected in milk samples (97.1%), followed by Hg (81.2%), Pb (50.6%), and Cd (38.0%). Their median breast milk concentrations were 1.49 μg/L, 0.26 μg/L, 0.14 μg/L, and <0.04 μg/L, respectively. Concentrations of As were higher in breast milk from primiparous donors, while Hg was higher in donors with a greater intake of fatty fish and meat and lower in samples collected after a longer post-partum time and with higher lactose content. Detection of Pb was higher among multiparous donors, those gaining weight since before pregnancy, and ex-smokers and was lower in samples collected more recently and from donors with greater intake of red meat and eggs. Cd detection was higher for donors with university education and those with greater intake of fried and canned food and more frequent use of hand cream and was lower for donors with greater bread intake.

CONCLUSIONS

These findings reveal relatively high As concentrations, moderate Hg concentrations, and low Pb and Cd concentrations in pooled donor breast milk. Several factors including post-partum time, parity, smoking habit, and the intake of certain food items were associated with the metal content of milk samples.

Levels of mercury in Moroccan breast milk and the affecting factors: CONTAMILK study

This study aims to evaluate the level of mercury in the breast milk of Moroccan mothers and its association with several maternal parameters and habits, and to estimate the daily intake of the newborns. Inductively coupled plasma mass spectrometry (ICP-MS) was used to determine the concentrations of mercury in 70 colostrum samples. Indeed, a structured questionnaire was administrated during milk collection to report data concerning the maternal socioeconomic and anthropometric parameters, as well as dietary habits and smoking habits in the family, etc. The median of mercury in breast milk was 3,56 μg/L (range 1.64-124 μg/L) and exceeded normal levels of 1.7 μg/l, suggested by the World health organization in 99% of milk samples. Significant associations were found between mercury levels and the occurrence of previous miscarriages, anemia before pregnancy and vitamin & mineral supplementation during pregnancy, as well the frequency of consumption of cereals and the use of lipstick. The estimated daily intake was higher than the tolerable daily intake of the World health organization and the European food safety authority in 30% of newborns. These results need to be confirmed by multicenter studies to investigate the levels of mercury in the breast milk of the Moroccan population.

Health Risk Assessments of Selected Trace Elements and Factors Associated with Their Levels in Human Breast Milk from Pretoria, South Africa

While breast milk is the recommended food for infants up to at least six months, exogenously derived compounds such as trace elements have been widely reported in human milk which may make it become toxic or a source of pollutants to the infants. Numerous short- and long-term health effects have been associated with high body-burdens of trace elements, which are amplified in infants. The current study determined the levels and possible contributing factors of six trace elements in breast milk of nursing mothers from a local hospital in Pretoria. Extraction of trace elements employed a digestion technique using perchloric and nitric acid in a ratio of 1:3, while Inductively Coupled Plasma-Membrane Spectrophotometry was used to identify and quantify their levels in breast milk. Concentrations of Cr and Mn were the highest in breast milk, with values ranging from 0.30 to 5.72 µg/L and 0.23 to 5.13 µg/L, respectively. Levels of Co, As, Pb and Cd ranged from Collapse

Key Words

• arsenic
• breast milk and passive smoking
• chromium
• manganese

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MESH Headings

• Environmental Pollutants
• Female
• Humans
• Milk, Human/chemistry
• Risk Assessment
• South Africa
• Trace Elements/analysis

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Grants Collapse

Affiliation(s)

Joshua O. Olowoyo Department of Biology, Sefako Makgatho Health Sciences University, P.O Box 139, Pretoria 0204, South Africa; (L.R.M.); (P.M.M.)
Linda R. Macheka
Phiona M. Mametja

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Lead concentrations in breast milk of Moroccan nursing mothers and associated factors of exposure: CONTAMILK STUDY

The aim of CONTAMILK study was to estimate levels of contamination of breast milk (BM) of Moroccan nursing mothers by some xenobiotics including, lead (Pb), to identify associated factors of exposure and to determine the daily intake of newborns. Lead concentrations were determined in 70 samples of colostrum by ICPMS and a structured questionnaire was filled during milk collection to report participants' data. The median lead concentration was 908 μg/L (range 1.38-515,39 μg/L) and in 79 % of samples, levels were higher than the normal range reported by the World Health Organization (WHO) in BM (2-5 μg/L). Indeed, preterm delivery, frequency of use of cosmetic powders and lipsticks were significantly associated with the level of lead in BM. The estimated daily intake was greater than the tolerable daily intake (TDI) of the European food safety authority (0.5 μg/kg/day) for 39 babies and 6 babies according to the WHO (3.6 μg/kg/day).

Dietary Intake and Milk Micronutrient Levels in Lactating Women with Full and Partial Breastfeeding

BACKGROUND

Micronutrient intake and status in lactating women may impact micronutrient levels in milk.

OBJECTIVES

This study aimed to determine the micronutrient intake and status in lactating women, and their association with micronutrient levels in human milk.

METHODS

Lactating women were enrolled at 4-6 months postpartum. A 24h food recall was examined and nutrient intakes were analyzed using INMUCAL software. Human milk samples were collected to analyze calcium, copper, iron, and zinc levels. Plasma zinc and serum ferritin levels were determined.

RESULTS

Thirty-four women participated; 19 were classified as full breastfeeding and 15 as partial breastfeeding. Mean levels of calcium, copper, iron, and zinc in human milk were 243, 0.2, 0.2, and 1.56 mg/L, respectively. The prevalence of zinc deficiency (plasma zinc < 10.7 µmol/L) was 11.8%. No lactating women had iron deficiency. Nutrient intakes were lower than the recommended amounts in 38%-70% of participants, and were not correlated with corresponding nutrient levels in human milk. Multiple linear regression showed significant association between zinc levels in human milk and plasma for lactating women with full breastfeeding (β = 0.034, 95% confidence interval [0.003, 0.067], p = 0.040).

CONCLUSIONS

Lactating women were at risk of micronutrient deficiency. There was an association between zinc levels in human milk and plasma of lactating women with full breastfeeding. As the nutritional status of lactating women influences the quality of human milk, we should encourage good nutrient intake for lactating women.

Cadmium Contamination in Breast Milk of Moroccan Lactating Women and the Associated Factors: CONTAMILK Study

The objectives of this study were to assess levels of contamination of breast milk (BM) by cadmium (Cd) among lactating mothers from Rabat, Morocco, and to investigate its association with several maternal habits, parameters, and factors. In addition, to estimate the daily intake of the newborns. Cd concentrations were measured by inductively coupled plasma-mass spectrometry (ICP-MS) in 70 human milk samples collected between the 2nd and 5th day postpartum. Accuracy of the analysis was checked by various methods including the use of reference material. A structured questionnaire was filled during the collection of milk reporting data concerning anthropometric, sociodemographic parameters, dietary and cosmetic habits, etc. The median (range) of Cd in human milk was 0.49 μg/L (range 0.013-95.19 μg/L) respectively. In 21 (30%) of 70 samples, Cd levels were higher than the normal reported by the World Health Organization (WHO) in BM (< 1 μg/L). Indeed, several factors affect significantly Cd levels in BM of the mothers such as low maternal education level, preterm delivery, cesarean delivery, and area of residence. Also, the frequency of consumption of milk and dairy products as well dried fruits and wheat bread and the frequency of use of cosmetic powders. However, the daily intake of cadmium by the newborns was lower than tolerable daily intake of the WHO for 97% of them. Our results revealed low cadmium concentrations in human milk samples from Moroccan lactating mothers living in Rabat, also the association of some factors with the levels of contamination found in this population.

The mercury level in hair and breast milk of lactating mothers in Iran: a systematic review and meta-analysis

Exposure to mercury is one of the major global health concerns due to its stability, bioaccumulation and high toxicity. Therefore, the present study was conducted to assess the mean mercury level in hair and breast milk (BM) of Iranian lactating mothers (ILMs) through meta-analysis technique. We conducted a systematic literature search in online electronic databases included main domestic databases (SID, Magiran, Iran medex, Medlib and ISC) and international databases (Embase, Scopus and PubMed) for studies published between 2000 up 2018. Each process of research and evaluation of articles based on inclusion and exclusion criteria is done by two researchers, individually. From10 studies entered to meta-analysis process including 556 ILM, the mean hair mercury level (HML) and mean milk mercury level (MML) was estimated to be 0.15 μg/g (95 CI: 0.11-0.19, I2: 47.6%, P: 0.028) and 0.51 μg/l (95 CI: 0.28-0.74, I2: 1.9%, P: 0.421), respectively. In this meta-analysis, the mean HML and mean MML were estimated to be lower than the standard of World Health Organization (WHO). Although the mean mercury level in hair and BM of ILMs was lower than the WHO standard, but due to toxicity and serious concern of health, management and Periodic monitor are recommended in different cities of the country for evaluate the mercury levels in hair and BM of ILMs and to estimate the infant's exposure.

Systematic Review of the Literature of Factors Affecting the Exposure and the Levels of Lead in Human Breast Milk

Human milk may sometimes contain chemical contaminants, which could have adverse effects on neonates or nursing infants. Lead (Pb) is of considerable interest due to its toxicity and occurrence. Furthermore, it has been suggested that human milk is a significant potential source of lead exposure to nursing infants. A systematic literature search in PubMed, Science Direct, and Google Scholar databases was performed to identify relevant studies, published in English until 2017, that investigated and explored common factors affecting the level of lead in human milk among lactating women around the world. Forty-nine papers were rated and explored the effect of one or several factors on the level of lead in human milk from 28 countries and carried out over a wide time frame from 1983 to 2017 and through Europe, Asia, America, and Africa, reviewing more than 5,000 subjects. Place of residence, maternal age, stage of lactation, smoking habits, maternal dietary intakes, and parity were the mostly assessed factors among the studies and considered as the main factors affecting Pb levels in BM. Other factors were not studied well enough and considered minor because few surveys evaluated their impacts. However, the literature findings are very controversial.

Fluoride Exposure Induces Inhibition of Sodium-and Potassium-Activated Adenosine Triphosphatase (Na+, K+-ATPase) Enzyme Activity: Molecular Mechanisms and Implications for Public Health

In this study, several lines of evidence are provided to show that Na + , K + -ATPase activity exerts vital roles in normal brain development and function and that loss of enzyme activity is implicated in neurodevelopmental, neuropsychiatric and neurodegenerative disorders, as well as increased risk of cancer, metabolic, pulmonary and cardiovascular disease. Evidence is presented to show that fluoride (F) inhibits Na + , K + -ATPase activity by altering biological pathways through modifying the expression of genes and the activity of glycolytic enzymes, metalloenzymes, hormones, proteins, neuropeptides and cytokines, as well as biological interface interactions that rely on the bioavailability of chemical elements magnesium and manganese to modulate ATP and Na + , K + -ATPase enzyme activity. Taken together, the findings of this study provide unprecedented insights into the molecular mechanisms and biological pathways by which F inhibits Na + , K + -ATPase activity and contributes to the etiology and pathophysiology of diseases associated with impairment of this essential enzyme. Moreover, the findings of this study further suggest that there are windows of susceptibility over the life course where chronic F exposure in pregnancy and early infancy may impair Na + , K + -ATPase activity with both short- and long-term implications for disease and inequalities in health. These findings would warrant considerable attention and potential intervention, not to mention additional research on the potential effects of F intake in contributing to chronic disease.

Total, organic, and inorganic mercury in human breast milk: levels and maternal factors of exposure, systematic literature review, 1976-2017

This systematic review summarizes the finding of 58 studies from 33 countries, which assessed mercury concentrations in breast milk and the factors related to the level of contamination. We performed a literature search in Pubmed, Science Direct, and Google Scholar databases for studies published between 1976 and 2017 that are monitoring and measuring mercury in human breast milk and investigating the associated factors. Then, we extracted more information about the aim of the study, the country, samples size, time of lactation, mercury concentration, and other data. Most of the studies used mature milk or colostrum for analysis and in about 60% of them, the concentrations exceed significantly the limit set by the World Health Organization (WHO) of 1.7 µg/l; In addition, many factors and parameters were related to the level of mercury contamination in breast milk. Periodic monitoring surveys are recommended in each country to evaluate the level of mercury in milk of lactating women and to estimate the level of exposure of newborns.

Mercury, Lead, Cadmium, and Barium Levels in Human Breast Milk and Factors Affecting Their Concentrations in Hamadan, Iran

Breast milk is considered the best source of nutrition for all infants. However, exposure of newborns to toxic metals is of special interest due to their potential harmful effects. Thus, the primary aims of this study were to determine the concentration of toxic heavy metals including lead, mercury, cadmium, and barium in breast milk samples from Hamadan, Iran, in relation to some sociodemographic variables. A total of 100 breast milk samples were collected and their heavy metal contents were measured by inductively coupled plasma mass spectroscopy (ICP-MS). The median breast milk concentrations of Pb, Hg, and Ba were 41.9, 2.8, and 1.95 μg/L, respectively. Cd levels were < 1 μg/L in all samples. The Pb level in 94% of the samples was higher than the recommended Pb limit of < 5 μg/L in breast milk suggested by World Health Organization (WHO). Hg levels in 54% of the breast milk samples were higher than the normal mean concentration (1.7 μg/L) suggested by WHO. We found no correlation between Hg levels in breast milk and sociodemographic factors. Ba levels in all the breast milk samples were lower than the WHO's proposed health-based drinking water guideline (0.7 mg/L). Considering the results of the present study and the vulnerability of infants, along with the well-known toxicity of these metals, further studies are warranted to identify the main sources of exposure that contribute their concentration in breast milk, establish harmless intake values of toxic metals in breast milk, and develop preventive measures.

Detection of lithium in breast milk and in situ elemental analysis of the mammary gland

Breast feeding provides considerable benefits to the infant and mother. However, a lithium-based psychiatric medication may cause side effects in the child. Using laser induced breakdown spectroscopy (LIBS), trace lithium levels were observed in the breast milk of lactating rats administered with lithium treatment postpartum. Subsequently, the mammary glands of female rats were analyzed using LIBS, energy dispersive X-ray fluorescence spectroscopy, and inductively coupled plasma mass spectrometry. Key biological elements iron, magnesium, cobalt, calcium, phosphorus, sodium, iodine, potassium, sulfur, chlorine and zinc were observed. Lithium at 1.06 µg/g was measured in the mammary glands of treated subjects, but was below the limit of detection in controls. Lithium also increased iodine content in the glands. Lithium is present in the breast milk and mammary glands of lithium treated female subjects and this is the likely route of entry to breast-fed infants.

Lead, cadmium and arsenic in human milk and their socio-demographic and lifestyle determinants in Lebanon

INTRODUCTION

Exposure of newborns to toxic metals is of special interest due to their reported contamination in breast milk and potential harm. The aim of this study was to assess the occurrence and factors associated with lead, cadmium and arsenic contamination in breast milk collected from lactating mothers in Lebanon.

METHODS

A total of 74 breast milk samples were collected from primaparas according to guidelines set by the World Health Organization. A survey was administered to determine the demographic and anthropometric characteristics of participating lactating mothers. Dietary habits were assessed using a semi-quantitative food frequency questionnaire. The milk samples were analyzed for the presence of arsenic, cadmium and lead using microwave-assisted digestion and atomic absorption spectrophotometry.

RESULTS

Arsenic contamination was found in 63.51% of breast milk samples (mean 2.36 ± 1.95 μg/L) whereas cadmium and lead were detected in 40.54% and 67.61% of samples respectively (means 0.87 ± 1.18 μg/L and 18.18 ± 13.31 μg/L). Regression analysis indicated that arsenic contamination was associated with cereal and fish intake (p = 0.013 and p = 0.042 respectively). Residence near cultivation activities (p = 0.008), smoking status before pregnancy (p = 0.046), potato consumption (p = 0.046) and education level (p = 0.041) were associated with lead contamination. Cadmium contamination was significantly associated with random smoke exposure (p = 0.002).

CONCLUSION

Our study is the first in Lebanon to report toxic metal contamination in breast milk. Although estimated weekly infant intake of these metals from breast milk was found to be lower than the limit set by international guidelines, our results highlight the need for developing strategies to protect infants from exposure to these hazardous substances.

Assessment of cadmium levels in human breast milk and the affecting factors: A systematic review, 1971-2014

BACKGROUND

This is a first systematic review summarizing 43 years of research from 36 countries for the assessment of cadmium in breast milk, a suitable matrix in human biomonitoring.

OBJECTIVES

To report from the published literature the levels of cadmium in breast milk, and the affecting factors causing increase in cadmium concentrations. In addition, to gather several quantitative data that might be useful to evaluate the international degrees of maternal and infant exposure.

METHODS

We reviewed the literature published between 1971 and 2014, available on Pubmed, Science Direct, and Google Scholar, reporting quantitative data about cadmium levels in human breast milk. Information about the aim of the study, name of the country, period of collection of samples, size of samples, sampling method, time of lactation, mother's age, area of residence, cadmium concentration, and other data were extracted.

RESULTS

Sixty-seven studies were selected and included in this systematic review. Some concentrations greatly exceed the limit set by the World Health Organization (WHO); however, about 50% of the studies had less than 1 µg/L cadmium concentration (recommended by the WHO); as well as many factors have shown their implication in breast milk contamination.

CONCLUSIONS

Breast milk is a pathway of maternal excretion of cadmium. It is also a biological indicator of the degree of environmental pollution and cadmium exposure of the lactating woman and the nourished infant. Therefore, preventive measures and continuous monitoring are necessary.

Arsenic, lead, mercury and cadmium: Toxicity, levels in breast milk and the risks for breastfed infants

Metals are ubiquitous in nature, being found in all environmental compartments, and have a variety of applications in human activities. Metals are transferred by maternal blood to the fetus via the placenta, and exposure continues throughout life. For the general population, exposure comes mainly from water and food consumption, including breast milk. In this paper, we reviewed studies on the toxicity of arsenic, lead, mercury and cadmium, the toxic metals of most concern to human health, focusing on the potential risks to newborns and infants. A total of 75 studies published since 2000 reporting the levels of these metals in breast milk were reviewed. Lead was the metal most investigated in breast milk (43 studies), and for which the highest levels were reported (up to 1515µg/L). Arsenic was the least investigated (18 studies), with higher levels reported for breast milk (up to 149µg/L) collected in regions with high arsenic concentrations in water (>10µg/L). Data from 34 studies on mercury showed that levels in breast milk were generally higher in populations with high fish consumption, where it may be present mainly as MeHg. Cadmium levels in breast milk were the lowest, with means <2µg/L in most of the 29 studies reviewed. Results of risk assessments indicated that the intake of arsenic, lead and mercury by infants through breastfeeding can be considered a health concern in most regions of the world. Although the potential risks to infants are mostly outweighed by the benefits of breast milk consumption, it is essential that contaminants be continuously monitored, especially in the most critical regions, and that measures be implemented by health authorities to reduce exposure of newborns and infants to these metals, and thus avoid unnecessary health risks.

Concentration profiles of metals in breast milk, drinking water, and soil: relationship between matrices

The concentrations of Cd, Cr, Cu, Hg, Mn, Ni, Pb, Sn, and Zn were determined in breast milk of women living in Conceição das Alagoas, Minas Gerais, Brazil. The potential relationships between metal levels in samples of breast milk, drinking water, and soils collected in the study area were also established. Metal levels in breast milk, except Cr, were lower in comparison to WHO reference concentrations. Zinc was the predominant element in breast milk and drinking water samples, with a median level of 46.2 and 82.2 μg · L(-1), respectively. Soils presented a different pattern of metal concentrations with respect to those found in breast milk and drinking water, Chromium showed the highest median levels (148 mg · kg(-1)), while a certain predominance of Zn and Cu was also observed (47.0 and 43.0 mg · kg(-1), respectively). Similar profiles were observed when comparing metal concentrations in drinking water and breast milk (chi-square χ(2) = 14.36; p < 0.05). In contrast, breast milk-soil and drinking water-soil metal concentration profiles showed significant differences (χ(2) = 635.05 and χ(2) = 721.78, respectively; p < 0.05). These results indicate that drinking water is an important exposure pathway for metals to newborns through breast milk. Further studies should be aimed at assessing the body burdens of metals in that population and at evaluating the potential relationships in the concentrations in biological and environmental matrices as well as at estimating the contribution of dietary intake of metals. In addition, the presence of other chemical pollutants in breast milk should be also studied in order to assess the combined newborn exposure to other contaminants.

Quantitative analysis of toxic and essential elements in human hair. Clinical validity of results

Over the last three decades, there has been an increasing awareness of environmental and occupational exposures to toxic or potentially toxic trace elements. The evolution of biological monitoring includes knowledge of kinetics of toxic and/or essential elements and adverse health effects related to their exposure. The debate whether a hair is a valid sample for biomonitoring or not is still attracting the attention of analysts, health care professionals, and environmentalists. Although researchers have found many correlations of essential elements to diseases, metabolic disorders, environmental exposures, and nutritional status, opponents of the concept of hair analysis object that hair samples are unreliable due to the influence of external factors. This review discusses validity of hair as a sample for biomonitoring of essential and toxic elements, with emphasis on pre-analytical, analytical, and post-analytical factors influencing results.

Cadmium interacts with the transport of essential micronutrients in the mammary gland - a study in rural Bangladeshi women

Although the concentrations of the toxic metal cadmium in breast milk are generally low (< 1 microg/L), experimental studies indicated neurobehavioral and endocrine effects in the suckling offspring. The aim of the present study was to elucidate how cadmium is transported to breast milk by assessing interactions with essential micronutrients. The study is nested into a food and micronutrient supplementation trial conducted among pregnant women in Matlab, a rural area in Bangladesh, where malnutrition is prevalent and the cadmium exposure is relatively high. We measured cadmium in breast milk (BM-Cd; median 0.14 microg/kg; range <0.050-1.0 microg/kg), in erythrocytes (Ery-Cd; median 1.5 microg/kg; range 0.46-4.8 microg/kg) and in urine (U-Cd; median 0.63 microg/L; range 0.050-4.5 microg/L), using inductively coupled plasma mass spectrometry (ICPMS). We found a significant positive association between Ery-Cd and BM-Cd and a breast milk-plasma ratio of approximately 3-4, indicating no barrier against cadmium transport from plasma to breast milk. BM-Cd was positively associated with manganese (r(s)=0.56; p<0.01) and iron (r(s)=0.55; p<0.01) in breast milk, but not with plasma ferritin. On the other hand, BM-Cd was negatively associated with BM-Ca (r(s)=-0.17; p=0.05), indicating that cadmium inhibits the transport of calcium to breast milk. In conclusion, the present study may indicate that cadmium shares common transporters with iron and manganese for transfer to breast milk, but inhibits secretion of calcium to breast milk.