By Roberta Attanasio
Lead, a toxic heavy metal, is the well-known cause of a global epidemic. It has acute and chronic effects on human health, causing neurological, cardiovascular, renal, gastrointestinal, haematological and reproductive effects. Children under the age of 6 are especially vulnerable to lead poisoning, which can severely and adversely influence mental and physical development.
In the U.S., lead poisoning has been called the “silent epidemic” — children are exposed mostly because of the remodeling of old houses painted before lead paint was banned in 1978. Indeed, lead paint is one of the most common health hazards. Children exposed to lead experience brain damage, behavioral problems and developmental delays.
Recently (December 2013), a study found that high levels of lead in Washington D.C. water coincided with increased numbers of miscarriages in the early 2000s (Fetal Death and Reduced Birth Rates Associated with Exposure to Lead-Contaminated Drinking Water). In this case, exposure to lead in pregnant mothers was caused by a change in the drinking water disinfectant — the new chemical made the water more corrosive for lead pipes and plumbing, resulting in unintended release and transfer of lead to drinking water.
Human milk is a well-known source of lead exposure in infants. Lead is transported from the mother’s blood to breast milk — however, the mechanisms of this transport are not clear.
To better understand the role that breast milk plays in infant exposure to lead, Adrienne Ettinger (School of Public Health, Yale University) and her collaborators measured the concentrations of lead present in maternal blood, plasma, and breast milk samples at 1 month postpartum. They also measured the concentrations of lead present in infant blood samples at 3 months of age. The samples were collected during a study of lactating women in Mexico City, Mexico.
The results of the study (Maternal blood, plasma, and breast milk lead: lactational transfer and contribution to infant exposure) are published in the scientific journal Environmental Health Perspectives (January 2014). The scientists found that the concentrations of lead varied in all samples tested, and that lead may sometime concentrate in breast milk — in other words, the concentration of lead in breast milk may be higher than the concentration of lead in maternal plasma.
The scientists suggest that breast milk is a significant and important source of infant lead exposure. Testing the mothers’ blood for lead concentrations mat not give a reliable estimate of lead concentrations in their breast milk. Therefore, early testing of babies for lead levels may be important to avoid potential lead poisoning through breastfeeding.