Infant Exposure to Chemicals in Breast Milk in the United States: What We Need to Learn from a Breast Milk Monitoring Program

Article excerpt

The presence of environmental chemicals in breast milk has gained increased attention from regulatory agencies and groups advocating women's and children's health. As the published literature on chemicals in breast milk has grown, there remains a paucity of data on parameters related to infant exposure via breast-feeding, particularly those with a time-dependent nature. This information is necessary for performing exposure assessments without heavy reliance on default assumptions. Although most experts agree that, except in unusual situations, breast-feeding is the preferred nutrition, a better understanding of an infant's level of exposure to environmental chemicals is essential, particularly in the United States where information is sparse. In this paper, we review extant data on two parameters needed to conduct realistic exposure assessments for breast-fed infants: a) levels of chemicals in human milk in the United States (and trends for dioxins/furans); and b) elimination kinetics (depuration) of chemicals from the mother during breast-feeding. The limitations of the existing data restrict our ability to predict infant body burdens of these chemicals from breast-feeding. Although the data indicate a decrease in breast milk dioxin toxic equivalents over time for several countries, the results for the United States are ambiguous. Whereas available information supports the inclusion of depuration when estimating exposures from breast-feeding, the data do not support selection of a specific rate of depuration. A program of breast milk monitoring would serve to provide the information needed to assess infant exposures during breast-feeding and develop scientifically sound information on benefits and risks of breast-feeding in the United States. Key words: breast milk, chlorinated organic chemicals, depuration, dioxin, monitoring program, time trends. Environ Health Perspect 109:75-88 (2001). [Online 20 December 2000]

It has been known since the 1950s that environmental chemicals are present in breast milk (1), but this issue has gained attention over the past few years. For example, the U. S. Environmental Protection Agency (U.S. EPA) noted that indicators of potentially high childhood chemical exposure include chemicals in breast milk and proposed chemicals in breast milk as candidates for testing under the Children's Health Chemical Testing Program (2,3). In an address to the National Women's Health Leadership Summit, the U.S. EPA (4) announced that they had

   set tougher new standards for burning municipal waste--one of the largest
   sources of dioxin, which accumulates in human tissue and breast milk....

Further, the Endocrine Disruptor Screening and Testing Advisory Committee recommended that the U.S. EPA screen and potentially test "representative mixtures to which large ... segments of the population are exposed," including breast milk (5). Groups advocating for women's and children's health have also focused on chemicals in breast milk (6,7).

Although research has provided information on the types of chemicals likely to be found in breast milk and on the toxicologic aspects of many of these chemicals, there are few data on parameters related to infant exposure via breast-feeding, including those with a time-dependent nature. This type of information is necessary for performing exposure assessments without heavy reliance on default assumptions or on the limited databases currently available. In addition, data collected longitudinally provide information on trends in breast milk chemical levels, which indicate whether controls on sources of contaminants are effective. Without this type of information, it will continue to be difficult to provide a scientifically based and consistent message to interested parties (e.g., doctors, nurses, lactation specialists, and new mothers) on the risks and benefits of breast-feeding and to compare these to formula-feeding. …