Many mothers worry about whether formula or breastfeeding is better for their growing child. Formula is made with the hopes that all the same nutrients given from a mother’s milk would also be given from it. However, it is known to take second place to breast milk (1). Many people do not know that there are contaminants present in formula such as aluminum, silicon, cadmium, phytoestrogens (founding soy formula), phthalates and bisphenol-a, lead, nitrates, and atrazine (2). Unfortunately, even though the benefits and the many nutrients of breast milk are well publicized there may be lead in breast milk as well (3).


It has been known for years that breastfeeding causes a loss in bone mass (4). This is due to the fact that many of the infant’s nutrients come from calcium that is stored in the mother’s bone (4).  Although this is well known that bone loss occurs, it is of little health risk to child or mother. Scientists began to wonder if calcium is being released from the bone then what else is? Until 2002, the methods for testing human bone lead stores were invasive, however more recently, the K x-ray fluorescence (KXRF) was developed (5). This method estimates the point bone lead levels using a control (the study discussed below used Cd KXRF) with some errors occurring when the level is close to zero (6,7). With this new method it became possible to test a large group of breastfeeding mothers to determine if the lead is released, and whether it is significant or not.


Scientists, using the KXRF method, studied 425 lactating women from Mexico City with no occupational exposure to lead (8). Although none of the women had an occupational exposure, they were all known to have a cultural link of lead from food and storage containers of food (9,10). These women were studied from the birth of their baby to seven months afterwards, with
an exclusion method as shown below. The study found that the level of lead in the bone significantly decreased and the blood level of lead in the mother increased, concluding that breastfeeding does cause the release of lead into the bloodstream and hence the breast milk contains lead as well (5).

exclusion method for mothers

Exclusion Method for Mothers (8).


There is a six-point drop in IQ for every 10 microgram increase in lead blood level in a child (2). In general, due to the common pathways of lead and calcium, the infant will suffer from low weight and undeveloped bone structure. Lead is known to effect the development of neuro-pathways and stunt the child’s brain development. Lead exposure during young childhood has been linked to the onset of autism (11).

What to Do?

Even though bones might contain lead and it will be released during lactation, studies show that most women do not contain significant enough levels to cause harm to their child (12). If the mother was not exposed to large amounts of lead during her lifetime her child is at minimum risk. However if she lived in a house with lead paint, lead pipes, or had some occupational lead exposure she might want to consider alternatives. Normally, the healthiest method of feeding a baby is to breastfeed because of the nutrients not found in formula, but parents should stay informed because they might not know that are giving their child more than just nutrients.


Contaminants in Baby Formula

Loss of Bone Mass through the Life Cycle and in Pregnancy

Lead in Breast Milk

Autism Associated with Lead Exposure


(1) Health, News, and Articles. Breast Milk vs Formula (2007).

(2) Walker, M. Contaminants in Infant Formula. International Board Certified Lactation Consultant. (2002)

(3) Sanin, L.H. Acumulacion de plomo en hueso y sus efectos en salud. Departamento del Distrito Federal, Instituto Nacional de Salud Pública, 40 359–368 (1998).

(4) Abrams, S.A. Normal Acquisition and Loss of Bone Mass. Hormone Research 60 (Suppl. 3):71-76 (2003).

(5) Hu H. Bone lead as a new biologic marker of lead dose: recent findings and implications for public health. Environ Health Perspect 106(suppl 4):961–967 (1998).

(6) Hu, H., Rabinowitz, M., and Smith, D. Bone lead as a biological marker in epidemiologic studies of chronic toxicity: conceptual paradigms. Environ Health Perspect 106, 1-7 (1998).

(7) Aro, A., Todd, A.C., Amarasiricwardena, C. et al. Improvement in the calibration of Cd K x-ray fluorence systems for measuring bone lead in vivo. Phys. Med. Bio. 27, 119-123 (2000).

(8) Tellez-Rojo, M.M., Hernandez-Avila, M., Gonzalez-Cossio, T., Romieu, I., Aro, A., Palazuelos, E., Schwartz, J., and Hu, H. Impact of Breastfeeding on the Mobilixation of Lead from Bone. American Journal of Epidemiology. 155 5 420-428 (2002).

(9) Hernández-Avila M. El plomo: un problema de salud pública en México. Departamento del Distrito Federal, Instituto Nacional de Salud Pública, 13–24 (1995).

(10) Romieu I, Palazuelos E, et. al. Fuentes de exposición a plomo en la Ciudad de México. Departamento del Distrito Federal, Instituto Nacional de Salud Pública, 13-24 (1995).

(11) Lidsky, T.I. and Schneider, J.S. Autisn and Autistic Symptoms Associate with Childhood Lead Poisoning. Journal of Applied Research.3 5 (2005).

(12) Sinks, T. and Jackson, R.J. Interntional Study Finds Breast Milk Free of Significant Lead Contamination. Environ Health Perspect. 107 2 (1999).

Author: Jessica Sheehan