Nutritional and Health-Related Environmental Studies

Stable isotope technique to assess human milk intake in infants living in contaminated areas

Background

The World Health Organization (WHO) recommends that infants should be exclusively breastfed for the first six months of life, followed by the introduction of appropriate complementary foods and continued breastfeeding for up to two years to achieve optimal growth, development and health [1]. Paediatricians and policy makers agree that protection, promotion and support of breastfeeding are a public health priority [2]. WHO classifies exclusively breastfed infants as receiving human milk and nothing else; predominantly breastfed infants receive human milk and small amounts of other fluids (teas, water or juice) on at least three days a week; partially breastfed infants receive human milk plus complementary foods including cow milk and infant formula [3]. In the youngest children (0-6 months), human milk forms the main source of nutrition and still makes a substantial contribution to nutrient intake at 9 months. Infants are particularly vulnerable since human milk is their sole or primary source of nutrition, and there is no information available on the effect of environmental contamination on lactation performance of women living in contaminated areas. The traditional method of assessing human milk intake is based on weighing the baby before and after each feed. This method is very time consuming and difficult to use in settings where the infants are nursed frequently, including during the night. It is not accurate and may disturb the feeding pattern. Human milk intake and thus lactation performance can be assessed using stable isotope technique. The deuterium oxide dose-to-mother technique gives an accurate assessment of the quantity of human milk consumed by the infant without disturbing the feeding pattern. The volume of human milk consumed by the baby over a period of 14 days is assessed by giving an oral dose of deuterium-labelled water to the mother and measuring the appearance of deuterium in the body water of the baby, and its disappearance from the body water of the mother. The method is non-invasive as only saliva or urine is collected for analysis. In addition to human milk intake, the method also gives information on the quantity of water consumed from sources other than human milk, and can thus determine whether the infant is exclusively breastfed or not [4-6]. Human milk is used in human biomonitoring as an indicator for accumulation of environmental chemicals. Evidence about toxic and potentially toxic chemicals in human milk can be used to promote environmental protection issues, but this can have an adverse effect on the public health messages issued by WHO. This issue had been highlighted recently [7, 8]. Although there is data on the concentration of toxic and potentially toxic compounds in human milk from biomonitoring programmes, there is very little accurate data on the quantity of human milk consumed by breastfed infants, particularly where environmental pollution occurs. Both concentration and volume are required to calculate the quantity of nutrients and contaminants transferred from mother to child in human milk. The alternative to breastfeeding for mothers living in contaminated areas is formula made with contaminated water. Breastfeeding is safer and cheaper than formula feeding and has significant advantages for the mother and her baby. The focus of most human milk biomonitoring programmes has been on persistent, bioaccumulative organic compounds [9, 10]. To date, there are few reliable data on the quantity of toxic and potentially toxic elements, such as lead (Pb), mercury (Hg), arsenic (As) cadmium (Cd), selenium (Se) and manganese (Mn), consumed by breastfed infants through human milk. It is known that arsenic readily crosses the placenta, but data on post-natal exposure via human milk are inconclusive [11-13]. Mercury in the bodies of lactating women is associated with fish in the diet and amalgam fillings in teeth, as well as living in an industrial environment [14-19]. There is some preliminary information that the mammary gland is an effective filter of Hg and As, but data is limited to just a few studies [11, 12, 14]. The proposed project will use a longitudinal study design with repeated measures of human milk intake by exclusively and predominantly breastfed babies living in contaminated areas, at age 3, 6 and 9 months. Samples of human milk will be collected for analysis of Hg, Pb, As, Cd, Se and Mn, depending on the study location. Chemical speciation of As and Hg will be performed as these elements exist in both organic and inorganic forms in biological systems, and the toxicity varies depending on the chemical form. The infants' intake of these toxic and potentially toxic elements through human milk will be measured by combining total element concentration in human milk with accurate estimates of human milk intake. The infants' growth will be monitored with reference to the new WHO growth standards based on breastfed infants [20], and they will be monitored for incidence of infectious diseases. This is the first IAEA supported project where quantification of human milk intake is combined with measures of concentration of toxic and potentially toxic elements and assessment of lactation performance of mothers living in contaminated areas. The results generated within this CRP will contribute new data towards the evidence base supporting public health messages so that an informed decision can be taken.

Objective

Overall objective

The overall objective of the proposed CRP is to assess lactation performance of women living in contaminated areas and to provide better estimates of transfer of toxic and potentially toxic elements from mother to child via human milk.

Specific objectives

Assess the intake of human milk by exclusively or predominantly breastfed babies, and to assess intake of water from other sources, using the deuterium oxide dose-to-mother technique.
Measure total element concentration (and speciation when applicable) of lead (Pb), mercury (Hg), arsenic (As), cadmium (Cd), selenium (Se) and manganese (Mn) in human milk, depending on the study location.
Evaluate the intake of toxic and potentially toxic elements though human milk by combining data on the concentration with data on the volume of human milk consumed by the baby.

Expected research outputs

New data on the intake of human milk by exclusively or predominantly breastfed infants, and information on water from other sources.
New data on concentration of toxic and potentially toxic elements in human milk.
New data on the transfer of toxic and potentially toxic elements from mother to infant via human milk.Publications in the form of scientific reports and peer-reviewed papers.

Expected Research Outcomes

Results from this CRP will aid in the evaluation of the benefits and risks of breastfeeding for infants living in contaminated areas, so that informed decisions can be taken.

Proposal submission forms

Research institutions in Member States interested in participating in this CRP are invited to submit proposals directly to the Research Contracts Administration Section (NACA) of the International Atomic Energy Agency: Official.Mail@iaea.org or to Ms Christine Slater: C.Slater@iaea.org. The forms can be downloaded from http://www-crp.iaea.org/html/forms.html. For more information about research contracts and research agreements, please visit our web-site: http://www-crp.iaea.org/html/faqs.html.

Deadline for submission of proposals

Proposals must be received no later than 7 August 2009.
Transmission via Email is acceptable if all required signatures are scanned.

For additional information, please contact:
Christine Slater, Nutrition Specialist
Nutritional and Health-Related Environmental Studies Section
Division of Human Health
International Atomic Energy Agency (IAEA)
Wagramer Strasse 5
A-1400 Vienna, Austria
Phone: +43-1-2600-26059 or 21681
Fax: +43-1-2600-7
C.Slater@iaea.org

References

[1] WORLD HEALTH ORGANIZATION, Global strategy for infant and young child feeding, WHO, Geneva (2003).
[2] AMERICAN ACADEMY OF PAEDIATRICS, Policy Statement: Breastfeeding and the use of human milk, Pediatrics 115 (2005) 496-506.
[3] WORLD HEALTH ORGANIZATION, Complementary feeding of young children in developing countries: a review of current scientific knowledge, WHO, Geneva (1998).
[4] COWARD, W.A., COLE, T.J., SAWYER, M.B., et al., Breast-milk intake measurement in mixed-fed infants by administration of deuterium oxide to their mothers, Hum. Nutr. Clin. Nutr. 36C (1982) 141-148.
[5] HAISMA, H., COWARD, W.A., ALBERNAZ, E., et al., Breast milk and energy intake in exclusively, predominantly and partially breast-fed infants, Eur. J. Clin. Nutr. 57 (2003) 1633-1642.
[6] MOORE, S.E., PRENTICE, A.M., COWARD, W.A., et al., Use of stable-isotope techniques to validate infant feeding practices reported by Bangladeshi women receiving breastfeeding counselling, Am. J. Clin. Nutr. 85 (2007) 1107-1082.
[7] RABIN, R.C., Despite worries over toxins, breast-feeding still best for infants, New York Times (2008) December 19.
[8] ARENDT, M., Communicating human biomonitoring results to ensure policy coherence with public health recommendations: analysing breastmilk, while protecting, promoting and supporting breastfeeding, Environ. Health 7 (Suppl 1) (2008) S6-S11.
[9] FENTON, S.E., CONDON, M., ETTINGER, A.S., et al., Collection and Use of exposure data from milk biomonitoring in the Unites States, J. Tox. Environ. Health, A 68(20) (2005) 1691-1712.
[10] LAKIND, J.S., BRENT, R.L., DOURSON, M.L., et al., Human milk biomonitoring data: interpretation and risk assessment issues, J. Toxicol. Environ. Health A. 68(20) (2005) 1713-1769.
[11] SAMANTA, G., DAS, D., MANDAL, B.K., et al., Arsenic in the breast milk of lactating women in arsenic-affected areas of West Bengal, India and its effect on infants, J Environ. Sci. Health, A Tox. Hazard Subst. Environ. Eng. 42(12) (2007) 1815-1825.
[12] FÄNGSTRÖM, B., MOORE, S. NERMELL, B., et al., Breast-feeding protects against arsenic exposure in Bangladeshi infants, Environ. Health Perspect. 116(7) (2008) 963-969.
[13] CONCHA, G., VOGLER, G., NERMELL, B., VAHTER, M., Low-level arsenic excretion in breast milk of native Andean women exposed to high levels of arsenic in drinking water, Int. Arch. Occup. Environ. Health 71(1) (1998) 42-46.
[14] DOREA, J.G., Mercury and lead during breast-feeding, Br. J. Nutr. 92(1) (2004) 21-40.
[15] DA COSTA, S.L., MALM, O., DOREA, J.G., Breast-milk mercury concentrations and amalgam surface in mothers from Brasilia, Brazil, Biol. Trace Elem. Res. 106(2) (2005) 145-151.
[16] DOREA, J.G., DONANGELO, C.M., Early (in uterus and infant) exposure to mercury and lead, Clin. Nutr. 25(3) (2006) 369-376.
[17] URSINYOVA, M., MASANOVA V., Cadmium, lead and mercury in human milk from Slovakia, Food Addit. Contam. 22(6) (2005) 579-589.
[18] CHIEN, L.C., HAN, B.C., HSU, C.S., et al., Analysis of the health risk of exposure to breast milk mercury in infants in Taiwan, Chemosphere., 64(1) (2006) 79-85.
[19] GRANDJEAN, P., BUDTZ-JØRGENSEN, E., STEUERWALD, U., et al., Attenuated growth of breast-fed children exposed to increased concentrations of methylmercury and polychlorinated biphenyls, FASEB J. 17(6) (2003) 699-701.
[20] WORLD HEALTH ORGANIZATION, The WHO Child Growth Standards, http://www.who.int/childgrowth/standards/en/
[21] JENNINGS, G., BLUCK, L., WRIGHT, A., et al., The use of infrared spectrophotometry for measuring body water spaces, Clin. Chem. 45(7) (1999) 1077-1081.