Serum Persistent Organic Pollutants and Duration of Lactation among Mexican-American Women

Background. Research suggests that estrogenic endocrine-disrupting chemicals interfere with lactation. Objectives. (1) to determine if estrogenic persistent organic pollutants (POPs) are associated with shortened lactation duration; (2) to determine whether previous breastfeeding history biases associations. Methods and Results. We measured selected organochlorines and polychlorinated biphenyls (p, p′-DDE, p, p′-DDT, o, p′-DDT, β-hexachlorocyclohexane, hexachlorobenzene, and PCBs 44, 49, 52, 118, 138, 153, and 180) in serum from 366 low-income, Mexican-American pregnant women living in an agricultural region of California and assessed breastfeeding duration by questionnaires. We found no association between DDE, DDT, or estrogenic POPs with shortened lactation duration, but rather associations for two potentially estrogenic POPs with lengthened lactation duration arose (HR [95% CI]: 0.6 [0.4, 0.8] for p, p′-DDE & 0.8 [0.6, 1.0] for PCB 52). Associations between antiestrogenic POPs (PCBs 138 and 180) and shortened lactation duration were attributed to a lactation history bias. Conclusion. Estrogenic POPs were not associated with shortened lactation duration, but may be associated with longer lactation duration.