Are breastfed or artificially-fed babies more likely to be lead-poisoned?

By Russell Ng and Hannah Beedham, Interns from Macquarie University

The advantages of breastfeeding

According to the Australian Breastfeeding Association, it is critical to breastfeed your baby, as  breast milk provides the needed nutrients for infants, protects them from infections and illness, and encourages the development of eyesight, speech and intelligence. Those who are not breastfed can have a higher risk of Sudden Infant Death Syndrome (SIDS) and an increased risk of allergies (ABA 2005). The World Health Organisation (WHO) recommends that mothers exclusively breastfeed their babies for the first 6 months of their life. WHO defines exclusive breastfeeding as no other food or drink, including water, except breast milk (WHO 2002).

Breast milk lead concentrations

Lead has a bio-accumulative effect in the human body; thus mothers who have been exposed to excessive lead prior to breastfeeding are a problem for the nursing infant. The impact on the infant’s early development is heavily determined by the mother’s diet and nutritional status (Mead 2008). For example, as more than90% of lead in the adult body is stored in bone, there is the possibility that there will be a large redistribution of cumulative lead stores from bone into plasma and subsequently into breast milk, during periods of heightened bone turnover, such as during pregnancy and lactation (Ettinger et al 2004).

A study by Dillon et al (1974) concluded that studies on the measurement of lead concentration in breast milk were sparse, and that, despite differences in methods and periods of study, there had been no increase in lead concentrations in breast milk over the 40 years prior to their own study. However, it was noted that at the time there was no comparative data available concerning the lead content of breast milk from populations with a possibly higher risk of exposure. A study by Oskarsson et al (1995) looked at toxic elements that could be found in breast milk and therefore transferred to the infant. The study found that lead levels in the milk were significantly higher for women who lived near a lead-emitting metal smelter in Sweden, and attributed this to the increased mobilization of lead from bone into the bloodstream and subsequently excreted through breast milk, as mentioned previously.

Results from Ettinger et al (2004), however, indicate that levels of lead in breast milk are low, regardless of the mothers’ high cumulative lifetime exposure to lead. The authors even go so far as to criticize previously-published studies showing high breast-milk lead levels, as being a result of contamination and inaccurate analytical methods. A study by Gulson et al (1998) also came to the same conclusion that breast milk contributes minimally to blood lead concentration in infants up to 1 year old. In fact, findings by Gulson et al suggest that the high levels of lead in breast milk in other studies may have been due to contamination from the foil around the alcohol wipes used to clean nipples.

Infant formula lead concentrations

Nursing infant exposure to lead can also come from the ingredients used in infant formula milk, whether it is lead in the water or in the infant formula itself, as well as potentially from the feeding bottle or teat. Cruz et al (2009) define infant formula as, “when in liquid form, may be used either directly or diluted with water before feeding, as appropriate.” Infants who drink formula are at particular risk as well, due to consuming large volumes of potentially contaminated fluid relative to their body weight (Baum and Shannon 1997).

Ikem et al. (2002) looked into levels of elements in infant formula from USA, UK, and Nigeria and, even though lead was detectable in the UK and Nigerian samples, it did not exceed the 15µg Pb/L stipulated by the EU directive for lead in drinking water. (Note: the limit of 10µg/L is set for implementation on 25/12/2013 – SCHER 2011). However, the presence of any lead in infant milk is of concern, considering the sensitivity of an infant to lead's toxic effects. Another study performed by Cruz et al (2009) analysed heavy metals, including lead, in selected infant formula milks commercially available in the Philippines,  manufactured in 2008, and found that there was no presence of lead in the tested samples. They do, however, cite a study that reported that reconstitution of infant formula milk with tap water contaminated with heavy metals can result in much higher lead concentrations.

Table 1: Estimated exposure of a 3 months old child to lead and blood lead levels at different concentrations of lead in drinking water (From SCHER 2011).

From table 1 we can see that under all conditions, the daily intake of lead for formula-fed infants of 3 months of age is above the European Food Safety Authority’s (EFSA) accepted level of 0.5 µg/kg body weight per day (SCHER 2011).

In a further example, Baum and Shannon (1997) describe a situation of two infants who contracted lead poisoning when formula was prepared with a lead-soldered electric kettle. Other cases associated with lead poisoning from water contaminated during the preparation of infant formula had three formula preparation practices in common responsible for the incidences of lead poisoning. They were i) excessive water boiling, (ii) use of lead-containing vessels, and iii) morning (first-draw) water. Risks also exist in certain feeding bottles used for infant formula. According to Art Hazard News, studies had shown that lead was leached from crystal decanters and baby bottles into the beverages they hold. The lead content of warm infant formula was reported to have greatly increased after just 15 minutes in a lead crystal baby bottle. (AHN 1991),

Testing for a lead-soldered kettle

The following information is specific to readers in Australia, who may be concerned about whether their electric kettles are lead-soldered or not. They essentially have two choices: to test the kettle themselves by boiling water in it and testing the boiled water using lead test kits available from The LEAD Group, or to send their query about the safety of the kettle – or other consumer products - to the Australian Competition and Consumer Commission’s Product Safety Australia Division. The ACCC is responsible for ensuring that only safe products are available to consumers and for recalling products that they find to be unsafe. In 2005 the ACCC recalled all Russell Hobbs Mona Kettles due to the possibility that the kettles may leak lead into the water (ACCC, 2005).

Lead exposure from being fed breast milk or infant formula: Which poses the higher risk?

As previously noted, studies from Ettinger (2004) and Gulson (1998) have found results which indicate that lead levels in breast milk, regardless of the mother's previous exposure to lead, are low. With this in mind, the mother’s exposure to lead is more critical during foetal development than during breastfeeding, as the foetus is more vulnerable through placental transfer than milk (Mead 2008).

Preparation of infant formula may involve running the risk of using lead-contaminated water, as does heating in, or feeding from, a vessel containing lead. This is on top of the possibility of lead contamination of infant formula itself. “Because infant formula and other foods for infants contain lead in the water used for their preparation, breastfed infants are exposed to less lead (Gulson et al., 1998).” (SCHER 2011) A study by Ryu et al (1983) found that concentrations of lead in formulas prepared for 25 infants between birth and 112 days of age, ranged from 19 to 26 µg/L.

Provided breast feeding is possible, reasons to not use infant formula because of the risk of exposing the infant to lead may outweigh the advantages.

However, there have been some improvements, though not necessarily universally

According to Rabinowitz and Leviton (1985), there have been reductions in lead content of infant formulas which is attributable to improved packaging methods. Earlier soldering methods resulted in splashes of molten lead entering the can and contact between the solder and food, but the increased demand for bottled formula, more careful canning techniques, and different seam designs have resulted in lower dietary lead intakes among infants. However,  "They are the result of concerted efforts by federal government departments and thus they do not necessarily occur at all in less developed countries or even in developed countries where very little lead testing is done." (O’Brien 2011)

References

ACCC (Australian Competition and Consume Commission), Russell Hobbs Mona Kettle recall, 15 May 2005, www.recalls.gov.au/recalls_last30days.cfm?rcl_type=recalls_consumer&psa_id=11246 (Accessed 24 May 2011)

AHN (Art Hazard News) (1991), FDA Advice on Leaded Crystalware, vol. 14, no. 4, http://www.chicagoartistsresource.org/node/9282  (Accessed 11 April 2011)

Baum, C.R and Shannon, M.W (1997), The lead concentration of reconstituted infant formula, Journal of Toxicology: Clinical Toxicology, vol. 35, no. 4, pp. 371-375, AVAILABLE FOR PURCHASE FROM http://www.ncbi.nlm.nih.gov/pubmed/9204097

Cruz, G.C; Din, Z; Feri, C.D; Baloing, A.M; Gonzales, E.M; Navidad, H.M; Schlaaff, M.M.F; Winter, J (2009) ANALYSIS OF TOXIC HEAVY METALS (ARSENIC, LEAD, AND MERCURY) IN SELECTED INFANT FORMULA MILK COMMERCIALLY AVAILABLE IN THE PHILLIPINES BY ASS, E-International Scientific Research Journal, vol. 1, issue 1, pp. 40 - 51, http://www.eisrjc.com/journals/journal_1/4.pdf

Dillon, H.K; Wilson, D.J; Schaffner W (1974) Lead Concentrations in Human Milk, American Journal of Diseases of Children, vol. 128, no. 4, pp. 491 - 492, AVAILABLE FOR PURCHASE FROM http://www.ncbi.nlm.nih.gov/pubmed/4414068

Ettinger, A.S; Tellez-Rojo, M.M; Amarasiriwardena, C; Gonzalez-Cossio, T; Peterson, K.E; Aro, A; Hu, H; Hernandez-Avila, M (2004) Levels of lead in breast milk and their relation to maternal blood and bone lead levels at one month postpartum, Environmental Health Perspectives, vol. 112, no. 8, pp. 926 - 931, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1242024/pdf/ehp0112-000926.pdf

Gulson, B.L; Jameson, C.W; Mahaffey, K.R; Mizon, K.J; Patison, N; Law, A.J; Korsch, M.J; Salter, M.A (1998) Relationships of Lead in Breast Milk to Lead in Blood, Urine, and Diet of the Infant and Mother, Environmental Health Perspectives, vol. 106, no. 10, pp. 667 - 674, http://ehp03.niehs.nih.gov/article/fetchArticle.action?articleURI=info:doi/10.1289/ehp.
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Ikem, A; NwanKwoala, A; Odueyungbo, S; Nyavor, K and Egiebor, N (2002) Levels of 26 elements in infant formula from USA, UK, and Nigeria by microwave digestion and ICP–OES, Food Chemistry, vol. 77, issue 4, pp. 439 - 447, AVAILABLE FOR PURCHASE FROM http://cat.inist.fr/?aModele=afficheN&cpsidt=13708698

Mead, M.N (2008) Contaminants in Human Milk: Weighing the Risks against the Benefits of Breastfeeding, Environmental Health Perspectives, vol. 116, no. 10, pp. a426 - a436, http://ehp03.niehs.nih.gov/article/info%3Adoi%2F10.1289%2Fehp.116-a426

O’Brien, Elizabeth, Manager, Global Lead Advice and Support Service (GLASS), pers com by email, 24/5/11

Oskarsson, A; Hallen, I.P and Sundberg, J (1995)Gulson, B.L; Jameson, C.W; Mahaffey, K.R; Mizon, K.J; Patison, N; Law, A.J; Korsch, M.J; Salter, M.A (1998) Relationships of Lead in Breast Milk to Lead in Blood, Urine, and Diet of the Infant and Mother, Environmental Health Perspectives, vol. 106, no. 10, viewed 7 April 2011, http://ehp03.niehs.nih.gov/article/fetchArticle.action?articleURI=info:doi/10.1289/ehp.
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Exposure to Toxic Elements via Breast Milk, The Analyst, vol. 120, no. 3, pp. 765 - 770, AVAILABLE FOR PURCHASE FROM http://www.ncbi.nlm.nih.gov/pubmed/7741226

Rabinowitz, M; and Leviton, A (1985) Lead in Milk and Infant Blood: A Dose-Response Model, Archives of Environmental Health, vol. 40, no. 5, pp. 283 - 286. AVAILABLE FOR PURCHASE FROM http://www.ncbi.nlm.nih.gov/pubmed/4062363

Ryu, J.E; Ziegler, E.E; Nelson, S.E; and Fomon, S.J (1983) Dietary Intake of Lead and Blood Lead Concentration in Early Infancy, American Journal of Diseases of Children, vol. 137, pp. 886 - 891. AVAILABLE FOR PURCHASE FROM http://www.ncbi.nlm.nih.gov/pubmed/6613955

SCHER (Scientific Committee on Health and Environmental Risks), Opinion on Lead Standard in Drinking Water, 11 January 2011 http://ec.europa.eu/health/scientific_committees/environmental_risks/docs/scher_o_128.pdf