BACKGROUND: Breastmilk (BM) can be a vector for the transmission of toxic metals such as lead and Mercury. Exposure during infancy can negatively affect the central nervous system (CNS) and impair the cognitive development. Premature infants are particularly vulnerable to the exposure of heavy metals due to an underdeveloped blood brain barrier (BBB) and gastrointestinal tract, which can potentially increase the amount of heavy metals that are absorbed and reach the brain. Moreover, at this development period, infants have immature pathways of biotransformation and elimination, and lower blood calcium, which increases the antagonistic dependency between hypocalcemia and intestinal lead absorption. Lead and mercury are a public health hazard due to their widespread presence in the environment and toxic effects. Their concentration in the BM provides an indication about the degree of prenatal exposure. Currently the WHO recommended lead and mercury levels in BM is less than 5 μg/L and 1.7 μg/L respectively. When ample maternal breast milk is not available, infants receive either donor breast milk (DBM) or formula.
OBJECTIVE: The aim of the study is to:
1.Investigate the presence of Lead and Mercury in Donor breast milk (DBM) and Human-Based Milk Fortifier (HBMF).
2.Quantitate Lead and Mercury levels in DBM and HBMF.
3.Compare any detectable levels of lead and Mercury to the WHO limit values in breast milk.
METHODS: In our prospective pilot study, we collected 5 samples of DBM and 5 samples of human-based milk fortifier (HBMF) from the Neonatal Intensive Care Unit at the University of Maryland Medical Center. The samples were then diluted (1+9) with a solution containing 2% Nitric acid (HNO3) and 0.01% (v/v) Triton X-100 and analyzed three times to determine the lead and mercury concentration using inductively coupled plasma mass spectrometry (ICP-MS). The ICP-MS is an elemental analysis technology capable of detecting most of the periodic table of elements at milligram to nanogram levels per liter. The output of an ICP-MS is numerical, provided in counts per second.
RESULTS: The results of the analysis of DBM and HBMF are summarized in Table 1. One sample of DBM and one sample of human based breast milk fortifier (HBMF) had a lead concentration of 6.7 µg/L and 6 µg/L, respectively, which is higher than the WHO recommended limit of 5 µg/L. Although only one sample of DBM had mercury, the concentration was 5.7 µg/L, three times higher than the WHO recommended limit of 1.7 μg/L.
CONCLUSION: Our preliminary data showed that lead and mercury can be present in DBM and lead can be present in HBMF in a level that at least warrant a larger investigation with analysis of more samples and determination of the amount of lead and/or mercury that an infant potentially received. Our main goal is to stimulate the debate about the topic, and stress the importance of balancing the costs and benefits involved in implementing additional screening of donor breast milk.
