Biomonitoring Persistent and Non-persistent Chemicals in Human Breast Milk and Endocrine Disruption of Lactation

Breastfeeding has numerous benefits to mother and child including improved maternal post-partum health, maternal/child bonding, and infant neurodevelopment and immune function. However, concern has been expressed about potential health risks posed to infants from environmental chemicals in human milk. The Food Quality Protection Act of 1996 requires the United States Environmental Protection Agency to set pesticide tolerance levels in food that ensure the safety of sensitive sub-populations, particularly pregnant women and children. Maternal dietary and environmental exposures to organophosphate (OP), organochlorine (OC), carbamate, and pyrethroid pesticides and polychlorinated biphenyls (PCBs) may lead to measurable levels of these chemicals in breast milk and because some of these chemicals interfere with hormone regulation, a mother's ability to lactate may be compromised by exposure. Lactational exposures to infants are of particular concern because infants' metabolic, neurologic and other systems are developing leading children to be more susceptible to the hazards of pesticides than adults. Although persistent pesticides, such as dichlorodiphenyltrichloroethane (DDT), have been biomonitored in human milk for decades, there are few studies measuring non-persistent pesticides in milk and no studies examining potential sources of non-persistent pesticides in milk. Using data and samples from the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS), another study on peripartum pesticide excretion, and a study of breast milk samples collected from San Francisco Bay Area women, this research aimed to: 1) to determine whether persistent organic pollutants measured in the blood of CHAMACOS participants are associated with shortened lactation duration; 2) to measure and compare the chemical concentrations of OPs, OCs, carbamates, pyrethroids, and PCBs in the milk of women residing in an rural area with those of women residing in an urban region; and 3) to investigate whether concentrations of two non-persistent pesticides highly detected in milk are correlated with concentrations measured in other biological samples and determine the potential predictors or sources of maternal exposure.Maternal concentrations of potentially endocrine disrupting chemicals measured in maternal serum were not associated with shortened lactation duration. Breast milk samples from urban and agricultural populations contained all of the persistent chemicals measured and the non-persistent pesticides, chlorpyrifos and permethrin. Concentrations of these two non-persistent pesticides were positively, but not statistically significantly correlated with concentrations measured in the plasma and urine of the same women. Lastly, some dietary and household factors may be potential sources of exposure to the mothers studied. The proposed research will provide information on maternal exposure and lactational exposure of non-persistent and persistent pesticides and PCBs to our most sensitive population, infants. Understanding whether lactation is potentially disrupted and the extent of dietary exposures to infants will allow for informed policy decisions regarding the use of pesticides and for the design of effective interventions in order to ensure the safety of this food for infants.