Toxic metals in human milk in relation to tobacco smoke exposure

Several reports confirm the deleterious effects of tobacco smoking and exposure to second-hand smoke (SHS) resulting in changes in the composition of breast milk. The aim of our study was to compare the levels of selected essential, as well as, toxic metals found in colostrum (collected at day 1 ± 2 post-birth) and mature milk (1 month ± 7 days post-birth) of nonsmoking women (n = 52) compared to those found in women who smoke tobacco (n = 51) and women exposed to second-hand smoke during pregnancy and lactation (n = 47). Women's non-smoking or smoking status was determined by their responses to a questionnaire, including questions about others who may smoke in the home environment, and confirmed by measurement of cotinine in the blood serum by high performance liquid chromatography with diode array detector (HPLC-DAD). Inductively coupled plasma mass spectrometry (ICP-MS) and flame atomic absorption spectroscopy (F-AAS) techniques were used to determine the metal concentrations in colostrum and mature milk previously digested by a microwave mineralizer. We confirmed that exposure to tobacco smoke increases concentrations of heavy metals (cadmium and lead) in colostrum and mature milk. These increased concentrations of heavy metals may disturb the action of bioactive substances necessary for the optimal growth and development of newborns and infants. These findings support the need for increased concern and information to lactating women about preventing their exposure to cigarette smoking and SHS due to the adverse effects of tobacco smoke on breast milk with added risks to their infants.