The Contribution of Breast-feeding to the Depuration of DDE
Bruce C. Wainman, PhD
The presence of persistent organic halogens (POHs) in maternal plasma and milk has been recognized since the 1970s. Yet, the presence of these compounds in human milk poses a still undetermined risk to the health of mother and child. The vertical transfer of POHs during either pregnancy or after birth during breast-feeding remains a concern. The paucity of data on maternal plasma contaminant levels before and after long periods of breast-feeding poses a serious problem for researchers attempting to model contaminant changes in maternal plasma and contaminant transfer via milk to the baby. This issue is of clinical concern since there is inadequate data to model infant exposure to POHs, leading to uninformed decisions about risks and benefits of breast-feeding. To address this issue we carried out a longitudinal analysis of the association between maternal plasma p,p'-DDE (1,1-dichloro-2,2- bis(p-chlorophenyl) ethylene) load and breast-feeding duration and parity. This pesticide residue was chosen because it is both an ubiquitous and abundant POH. The women recruited for the study were 34.4 + 2.8 yr and had breast-fed an average of 2.1 children a total of 64.6 + 32.6 weeks when they were sampled at the end of the study. A questionnaire was used to determine the mother's breast-feeding activity. We found that the women had very low levels of p,p'-DDE in their plasma and milk compared to other populations in the world and that the trend in Canada towards lower contaminant loads has been sustained in our study population. The regression of change in plasma p,p'-DDE with breast-feeding duration is significant (p < 0.01, F = 15.80, and n=12). We found that maternal plasma p,p'-DDE levels changed by 0.0057 µg/L for every week of breast-feeding. Thus, women breast-feeding their infants lost, on average, 30 µg of this contaminant per week. These results suggest that maternal depuration of p,p'-DDE via breast-feeding is a significant cause of maternal contaminant loss and contaminant accumulation in the baby.
persistent organic contaminants, persistent organic halogens, DDE, breast-feeding, pollution, human milk
This article has been peer-reviewed.