September 23, 2003

Mother's Milk: Breast milk is still best

Evidence of the accumulation of chemicals in women’s bodies and breast milk may prompt mothers to question the safety of their breast milk as a food for their baby. However, the evidence is clear: Women should breastfeed their children and continue to do so for as long as possible. Breastfeeding provides significant health benefits to both mother and child. In fact, careful study of babies’ toxic exposures indicates that it might be even more important for mothers who are concerned about their exposure to toxic chemicals to breastfeed their babies.

Physicians investigating the hazards of chemical exposure via breast milk and the benefits of breastfeeding consistently support breastfeeding as the healthiest way to feed a child. [1, 2, 3] For both baby and mother, breastfeeding has many well-documented health benefits:

  • Breastfed babies have lower rates of some of the most serious chronic diseases: asthma [4], diabetes, [5] and some childhood cancers. [6, 7]
  • Breastfeeding reduces the risk and severity of communicable diseases: pneumonia, diarrhea, and ear infections. [2, 8]
  • Women who breastfeed have lower levels of ovarian and breast cancer, and breastfed daughters also have lower rates of breast cancer when they grow up.
  • Breastfeeding may even reverse some of the damage caused by chemical exposures in the womb.

Even with chemicals, breastfeeding is best

Breast milk is made up of fat from a mother’s body. Therefore it contains the same chemicals that accumulate in her body fat, such as PCBs and PBDEs. The developing baby is exposed to chemicals from their mother’s body from pregnancy until it is weaned. Even though breastfed infants are exposed to higher levels of chemicals over their first few years of life, they have lower levels of childhood cancers, breast cancer and other illnesses believed to be linked to chemical exposure.

Several long-term studies have followed groups of babies exposed to PCBs in-utero and found that the breastfed babies appear to be less impacted by the chemical exposures than their bottle-fed counterparts. [9, 10] One study of Michigan babies found significant improvements in babies’ breastfed for at least 6 weeks. The researchers concluded that PCB exposures in the womb were responsible for the neurological impacts, and that breastfed infants showed fewer effects of PCB exposure. [9]

Despite evidence that breastfeeding can protect against subtle health effects caused by in-utero chemical exposures, we should still be cautious with our children’s exposure to chemicals. Studies documenting extremely high levels of PCBs in Inuit children eating a subsistence diet have found that breastfed infants get as many ear infections as formula-fed babies, indicating that the PCBs may reduce some of the protective benefits of breastfeeding. [11] Another concern is that chemicals mimicking estrogen in a women’s body seem to make it difficult for her to produce breast milk, resulting in earlier weaning of children. [12, 13]

Concerns with infant formulas

Parents concerned about chemical contaminants should also consider the concerns associated with feeding infants formula rather than breast milk:

  • Mixing powdered formula with drinking water can expose children to chemical or bacterial contaminants. EWG has reported that infants under four months of age get more than seven times the dose of chemicals in tap water than an adult would get, relative to their body weight. Widespread contaminants of potential concern in drinking water include chlorine byproducts, pesticides, solvents, nitrates, lead, and arsenic. [14] Localized contaminants can also result in risk. As a result of widespread atrazine contamination in the Midwest, EWG estimated that 146,000 infants are born each year in regions with measurable atrazine in their drinking water supply, which provide a bottle-fed infant by age one with 25 percent of his or her lifetime allowable dose of atrazine. [15]
  • Breast milk is estimated to contain 160 fatty acids that are not included in baby formula. [16] These fatty acids have been linked to optimal brain development and better vision in breastfed babies. Two in particular have recently begun to be added to formulas-albeit at extra cost. “Superbaby formulas” supplemented with two omega-3 fatty acids, known as docosahexaenoic acid (DHA) and arachidonic acid (A.A.) are now available. [17]
  • There are unresolved concerns about the safety of manganese found in baby formula. Manganese is a neurotoxic chemical found in much higher concentrations in infant formula than in mother’s milk. In fact, soy-based formulas contain about 80 times more manganese than breast milk, and formulas made with animal protein about 30 times more. Studies conducted as early as the 1970s and 80s show an association between various learning or behavior problems and elevated manganese levels. [18] Infants are not able to absorb and excrete excess manganese during their first year of life, a period of rapid development. Developmental deficits have been reported in primates fed 50 to 100 ounces of Isomil per day. [19]

Protecting children’s health

In all but the most extreme circumstances, then, breast milk remains the best food for babies. [3] Yet we cannot ignore the increasing burdens of persistent contaminants in the bodies of mothers and children. Without knowing what chemicals are found in our bodies and our homes, or having a reasonable idea that these chemicals are safe, we have no way to protect our infants or children from exposure to toxic chemicals while they are in the womb or subsisting on mother’s milk. Chemicals like PBDEs and their replacements must be thoroughly tested for their safety, before they enter our homes, our environment, and our bodies.


[1] Greater Boston Physicians for Social Responsibility. 1999. What about breastfeeding?

[2] Greater Boston Physicians for Social Responsibility. 2002. Out of Harm’s Way: Preventing Toxic Threats to Child Development. Why breast-feeding is still best for baby.

[3] American Academy of Pediatrics (AAP). 1999. Polychlorinated biphenyls, dibenzofurans, and dibenzodioxins. In: Etzel RA, Balk SJ, editors. Handbook of Pediatric Environmental Health. p. 215-22.

[4] Oddy WH, Holt PG, Sly PD et al. 1999. Association between breast feeding and asthma in 6 year old children: findings of a prospective birth cohort study. British Medical Journal 319(7213):815-819.

[5] Mayer EJ, Hamman RF, Gay EC et al. 1998. Reduced risk of IDDM among breast-fed children. Diabetes. (37)1625-1632

[6] Davis MK. 1998a. Review of the evidence for an association between infant feeding and childhood cancer. International Journal of Cancer, Suppl (11)29-33.

[7] Davis MK, Savitz DA, Graubard BI. 1998b. Infant feeding and childhood cancer. Lancet. (2)365-368.

[8] American Academy of Pediatrics (AAP) 1997. Breastfeeding and the Use of Human Milk. Pediatrics Vol. 100(6):1035-39

[9] Jacobson, J.L.; Jacobson, S.W. 2002. Association of prenatal exposure to an environmental contaminant with intellectual function in childhood. Journ. Clin. Tox. 40(4): 467-75.

[10] Dekoning, E.P. and W. Karmaus. 2000. PCB Exposure in-utero and Via Breast Milk, A Review. Journal of Exposure Analysis and Environmental Epidemiology 10:285-293.

[11] Dewailly E, Ayotta P, Bruneau S, et al. 2000. Susceptibility to infections and immune status in Inuit infants exposed to organochlorines. Environmental Health Perspectives 108(3):205-211.

[12] Gladen BC, Rogan WJ. 1996. DDE and shortened duration of lactation in a northern Mexican town. Am J Public Health. Apr;85(4):504-8.

[13] Rogan WJ, Gladen BC, McKinney JD, Carreras N, Hardy P, Thullen J, Tingelstad J, Tully M. 1987. Polychlorinated biphenyls (PCBs) and dichlorodiphenyl dichloroethene (DDE) in human milk: effects on growth, morbidity, and duration of lactation. American Journal of Public Health. (77)10:1294-7.

[14] Natural Resources Defense Council (NRDC). 2001. Healthy Milk, Healthy Baby: Chemical Pollution and Mother's Milk.

[15] Environmental Working Group. 1999. Into the Mouths of Babes: Bottle-fed Infants at Risk from Atrazine in Tap Water.

[16] Kaufman, M. 1999. FDA revising regulations to improve baby formula. Washington Post September 14, 1999.

[17] Retsinas, G. New York Times. 2003. The Marketing of a Superbaby Formula. June 1, 2003.

[18] Collipp PJ. Manganese in infant formula and learning disability. Ann Nutr Metab 27:488-494. 1983.

[19] Van Scoy, H. Soy-based formulas may be linked to ADHD: elevated levels of manganese the suspected culprit. Health Scout News Reporter. October 8, 2002.