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MEASUREMENT OF PHTHALATE LEVELS IN HUMAN MILK IN THE US EPA MAMA STUDY
Citation:
HINES, E. P., R. R. BARBEE, J. RAYNER, A. CALAFAT, AND S. E. FENTON. MEASUREMENT OF PHTHALATE LEVELS IN HUMAN MILK IN THE US EPA MAMA STUDY. Presented at Endocrine Meeting, Boston, MA, June 23 - 26, 2006.
Description:
Phthalates are plasticizers used to impart flexibility in products including PVC, plastic toys, and medical devices. These products are widely used by the general population. Phthalates act as anti-androgens and in utero or perinatal exposure in laboratory animal models leads to testicular dysfunction. Effects of phthalates in humans are largely unknown. The US EPA conducted a study entitled Methods Advancement in Milk Analysis (MAMA) in which lactating mothers visited the clinic twice (visit one 2-7 weeks post-partum, visit two 3-4 months post-partum) to donate milk samples for analysis of environmental and endogenous compounds. In this assay, eleven monoester phthalate metabolites were measured: mono-n-butyl phthalate (MBP), mono(2-ethylhexyl) phthalate (MEHP), mono-ethyl phthalate (MEP), mono(2-ethyl-5-hydroxyhexyl) (MEHHP), mono-iso-butyl phthalate (MIBP), mono-isononyl phthalate (MNP), monobenzyl phthalate (MBzP), mono-3-carboxypropyl phthalate (MCPP), mono-methyl phthalate (MMP), monooctyl phthalate (MOP) and mono(2-ethyl-5-oxyhexyl) (MeOHP). Of these metabolites, MNP, MEP, MBP, and MEHP were detectable in the milk samples. MNP (69%) was the primary metabolite detected, with MEHP (49%), MEP (7%), and MBP (1.4 ng/ml, n=1) also found in the milk. The mean (+SEM) human milk MNP, MEHP and MEP concentrations were 2.6+ 0.27, 3.1+0.26, and 2.2+0.38 ng/ml, respectively. Of the 11 phthalate metabolites measured, we frequently detected MNP in both collection times and MEHP was detected nearly equally in both sets (visit 1 n =12, visit 2 n=13). From this preliminary work, it appears that MEHP increased in visit 2 to 3.6+0.26 ng/ml from 2.4+0.22 ng/ml in visit 1. MEP was detected only in the first collection milk samples. Previous work in our lab showed that there was no significant increase in phthalate levels during transition through the commercial pump used for milk collection. This study shows preliminary data on levels and types of phthalates that reach the infant through breast milk. (This abstract does not necessarily reflect EPA policy.)