While breastfeeding is still the preferred source of infant nutrition by the AAP, a little-known fact is that breastfeeding may expose the nursing infant to environmental pollutants to which they might not normally be exposed. If you have a mother that appears ill due to exposure to any of these agents, don't forget to have the infant examined as well for signs of intoxication.
Breastmilk can contain approximately 20% of the maternal toxin load, which can produce more severe effects in the infant due to the vastly different dose/weight ratio
Toxin load is usually due to the lipid solubility of agents
Formulas are safe due to the nature of their fat sources; cows usually have a much lower exposure rate to pollutants, and those that are ingested are much more dilute due to the volume of milk produced in comparison to a human female; also, with non-cows'-milk formulas, the lipid components are usually plant-derived and thus also with a lower risk of exposure
Common offending agents include: DDT, PCBs, Dioxin, hexachlorobenzene, Halothane, carbon disulfide, nicotine, lead, methylmercury, Heptachlor, Chlordane, and tetrachloroethylene
References
American Academy of Pediatrics Committee on Environmental Health. Chapter 3. In: Etzel RA, ed. Pediatric Environmental Health, 2nd ed. Elk Grove Village, IL: American Academy of Pediatrics; 2003.
