Mixtures of serum concentrations of organochlorine pesticides and breastfeeding duration

The relationship between breastfeeding duration and maternal mixtures of organochlorine pesticides (OCP) biological concentrations has not been documented. For that reason, our objective was to evaluate the association between lactation duration and mixtures of OCP serum concentrations and their principal metabolites, as well as to identify the primary contributors within these mixtures. Consequently, we conducted a secondary analysis of 878 women over 18 years old who had at least one living child and served as controls in a population-based study from 2007 to 2011 in Northern Mexico. Through direct interviews, we collected data on breastfeeding duration, sociodemographic characteristics, and medical history. We determined serum concentrations of 24 OCP, including some metabolites, using gas chromatography with an electron microcapture detector. We applied Weighted Quantile Sum (WQS) regression models with binomial family specification to assess the relationship between breastfeeding duration (both for the first child and all children) and mixtures of OCP serum concentrations and their metabolites of interest. We identified a mixture of OCP negatively associated with breastfeeding the first child (OR = 0.63, 95% CI 0.52-0.77) and all children (OR = 0.59, 95% CI 0.46-0.75). The significant OCP or metabolites in both mixtures included p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE), trans-nonachlor, beta-hexachlorocyclohexane (beta-HCH), p,p'-dichlorodiphenyldichloroethane (p,p'-DDD), heptachlor, and hexachlorobenzene (HCB). Our results suggest serum concentrations of OCP mixtures in women who breastfed for at least 12 months are lower than those who breastfed for less than that time. Future studies are needed to evaluate the risk-benefit of multiple OCP in breast milk for maternal and child health.