Drugs and Chemical Contaminants in Human Breast Milk

Breast-feeding offers many advantages to neonates and infants, and provides a range of benefits for growth, immunity, and development. The main principles of drug excretion into breast milk and the different determinants such as the age-dependent factors affecting gastrointestinal absorption and the resulting pharmacokinetic outcomes relative to adult levels are addressed in this chapter. Analgesics, antibiotics, cardiovascular drugs, steroidal hormone drugs, antiepileptics, psychoactive drugs (sedative and hypnotics, antidepressants), anticoagulants, antihypertensives (beta-blockers, calcium channel blockers, methyldopa, angiotensin-converting enzyme inhibitors), nonmedicinal substances, and environmental pollutants (mainly persistent organic pollutants, endocrine-disrupting compounds, and heavy metals) in relation to their transfer through into the mother's milk are described. This chapter also reviews the literature on herbs contraindicated during pregnancy and lactation; the potential adverse effects of recreational drugs in the mothers, suckling neonates, and infant; and the presence of environmental chemical pollutants in human milk. Levels of chemical contaminants in human milk fat are a good indicator of potential future public health and environmental problems. The presence of environmental contaminants such as persistent organic pollutants (i.e., aldrin, chlordane, dichlorodiphenyltrichloroethane, dieldrin, endrin, heptachlor, hexachlorobenzene, mirex, toxaphene, polychlorinated biphenyls, polychlorinated dibenzodioxins, and polychlorinated dibenzofurans), poly and perfluoroalkyl substances, endocrine-disrupting compounds such as bisphenol A, di-(2-ethylhexyl) phthalate, and nonylphenols and heavy metals (lead, cadmium, mercury, arsenic) in human milk is discussed. Risk management should aim to reduce life-long exposure particularly during the prenatal period and pregnancy since toxic chemicals accumulate long before pregnancy and are released during gestation and lactation.