| Infant Exposure to Dioxin-like Compounds in Breast Milk Matthew Lorber1 and Linda Phillips2 1National Center for Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, Washington, DC, USA; 2Versar Inc., Springfield, Virginia, USA Abstract
We used a one-compartment, first-order pharmacokinetic model to predict the infant body burden of dioxin-like compounds that results from breast-feeding. Validation testing of the model showed a good match between predictions and measurements of dioxin toxic equivalents (TEQs) in breast-fed infants, and the exercise highlighted the importance of the assumption of the rate of dissipation of TEQs in the infant. We evaluated five nursing scenarios: no nursing (i.e., formula only) , and nursing for 6 weeks, 6 months, 1 year, and 2 years. We assumed that an infant weighs 3.3 kg at birth and is exposed to a total of 800 pg TEQ/day by consumption of breast milk, leading to an estimated body weight-based dose of 242 pg TEQ/kg-day, which drops to 18 pg TEQ/kg-day after 1 year. This decline is due to declines in dioxin concentration in mother's milk and infant body weight increases. This range is significantly higher, on a body-weight basis, than adult TEQ exposure, which has been estimated to average about 1 pg TEQ/kg-day. For the nursing scenarios of  6 months, we predict that body burdens (expressed as a body lipid concentration) peak at around 9 weeks at 44 ppt TEQ lipid. We predict that the body burden of the formula-fed infants will remain below 10 ppt TEQ lipid during the first year. These results compare to the current adult average body burden of 25 ppt TEQ lipid. We also found that an infant who had been breast-fed for 1 year had an accumulated dose 6 times higher than a 1-year-old infant who had not been breast-fed. For a 70-year lifetime, individuals who had been breast-fed had an accumulated dose 3-18% higher than individuals who had not been breast-fed. Key words: breast milk, dioxin-like compounds, dioxins, furans, infant exposure, pharmacokinetic modeling. Environ Health Perspect 110:A325-A332 (2002) . [Online 13 May 2002] http://ehpnet1.niehs.nih.gov/docs/2002/110pA325-A332lorber/ abstract.html Address correspondence to M. Lorber, National Center for Environmental Assessment (8623D) , Office of Research and Development, U.S. Environmental Protection Agency, 1200 Pennsylvania Avenue NW, Washington, DC 20460 USA. Telephone: (202) 564-3243. Fax: (202) 565-0078. E-mail: lorber.matthew@epa.gov This article is part of the mini-monograph "Chemical Contaminants in Breast Milk: Impact on Children's Health." The views expressed in this article are those of the authors and do not necessarily reflect the views or policies of the U.S. Environmental Protection Agency. Received 20 December 2001 ; accepted 22 March 2002.
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