Concentrations of Lead and Arsenic in Mother’s Milk and Children’s Blood in Peruvian Breastfeeding Dyads

Background: Toxic trace elements could enter human milk through mothers’ food consumption, drinking water, air, or incidental soil ingestion, and are of concern to the nursing infant. Research Aim: To determine the concentration of toxic trace elements (lead and arsenic) in Peruvian mothers’ milk and their association with blood concentrations in their own infants 3–20 months old. Method: This exploratory, cross-sectional study, carried out in Peru, included breastfeeding mother/child dyads (N = 40). Following standardized protocols, biospecimens of human milk and child’s blood were collected. Results: Lead and arsenic concentrations in milk were above the method detection limits in 73% and 100% of samples with median concentrations of 0.26 µg/L (IQR = 0.10, 0.33 µg/L) and 0.73 µg/L (IQR = 0.63, 0.91 µg/L), respectively. Concentrations of lead and arsenic in blood were 2.05 µg/dL (SD = 1.35), and 1.43 µg/dl (geometric mean: SD = 1.39), respectively. Blood lead concentrations in 12.5% (n = 5) of the samples were above the U.S. Center for Disease Control and Prevention reference value (< 3.5 µg/dl), and over half of arsenic concentrations were above the acceptable levels of < 1.3 µg/dl (Mayo Clinic Interpretative Handbook). Our results showed that for every one-month increase in age, lead blood concentrations increased by 0.1 µg/dl (p = 0.023). Additionally, every 1 µg/L increase in the mother’s milk arsenic was associated with a 1.40 µg/dl increase in the child’s blood arsenic concentration. Conclusions: Implementing effective interventions to decrease the toxic exposure of reproductive-aged women is needed in Peru and worldwide.