Pharmacokinetics of Toxic Chemicals in Breast Milk: Use of PBPK Models to Predict Infant Exposure (original) (raw)

2002, Environmental Health Perspectives

Maternal milk has been recognized by public health officials as the most beneficial source of nourishment during infancy. The U.S. Department of Health and Human Services, through the Healthy People 2010 objectives, has set a target goal of early postpartum breast-feeding rates of 75% by the year 2010 (1). This emphasis on breast-feeding is motivated by the fact that breast milk provides the most complete form of nutrition for infants, imparts increased protection from diseases, and improves maternal health through the physiologic responses associated with lactation. However, potential risks associated with breast-feeding also need to be factored into the overall public health assessment when women are encouraged to breastfeed their newborn infants (2). For example, through the process of breast-feeding, it is possible for the mother to transfer to the suckling infant potentially toxic chemicals to which the mother has previously been exposed. Due to the rapid mental and physical changes that are taking place, neonates can be more susceptible to adverse effects resulting from chemical exposures (2,3). Historically, the study of prescription drugs has provided a basis for understanding the governing principles behind transfer of chemicals through breast milk (4). These factors can be separated into two broad categories: maternal characteristics and chemical characteristics (5,6). Maternal characteristics include the degree of maternal exposure, physiology of the mother, maternal age, and parity (number of pregnancies). Chemical characteristics refer to aspects of the compound that affect its ability to be taken up in milk, such as the lipid solubility, degree of ionization, molecular weight, and ability to bind to maternal blood and/or milk components.