Evidence for Maternal-Fetal-Infant Transfer of Phthalates

Written by Angeline A. De Leon, Staff Writer. Study results suggest a potential transfer of maternal-fetal- infant transfer of phthalates and that meconium may be a useful matrix for measuring in utero exposure to phthalates.

Phthalates, often called plasticizers, are a family of chemicals primarily used to make plastic more flexible and difficult to break. These compounds can be found in everything from adhesives and detergents to automotive plastics and hair sprays. Studies show that various phthalates have estrogenic activity and anti-androgenic properties ¹, and toxicological reports now consider phthalates to be reproductive and developmental toxicants ². Prenatal exposure to phthalates has been linked to premature birth ³, decreased anogenital distance in male babies ⁴, and abnormal cognitive and motor development of children ^5,6. A number of human biomonitoring studies have examined phthalates in pregnant women and their infants ^7-9, however, data on the correlation between maternal and infant exposure to phthalates over multiple sampling periods is still needed. Thus, in a 2015 study ¹⁰ published in Science of the Total Environment, researchers in Canada conducted the first study to examine phthalates exposure across pregnancy and into the early post-natal period, using several biospecimens, including maternal urine, breast milk, infant urine, and meconium (earliest stool of infant).

A total of 80 pregnant women (< 20 weeks gestation) aged 18 years and older were recruited as participants and were followed prospectively through pregnancy up to 2-3 months postnatally. Serial urine samples over a 24-h period were collected from women at < 20 weeks, during the second trimester, third trimester, and 2-3 months post-partum. Infant urine was collected within the first month and 2-3 months post-partum, and meconium was collected within the first two days after delivery. Mothers were instructed to collect a 150 mL sample of breast milk 2-3 months post-partum and also completed a questionnaire regarding occupation, socioeconomic status, and smoking, as well as infant feeding and care practices post-partum. Biospecimens from mothers and infants were chemically analyzed for various phthalate metabolites, such as mono-methyl phthalate (MMP), mono-cyclohexyl phthalate (MCHP), and mono-isononyl phthalate (MiNP).

Over the course of the study, at least 50% of women had at least one urine sample greater than the limit of detection for MMP, MCHP, and monohydroxyisodecyl phthalate (MHiDP). At any time point, mono-benzyl phthalate (MBzP), mono-3-carboxypropyl phthalate (MCPP), mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), and mono-(2-ethyl-5-oxhexyl) phthalate (MEHOP) were frequently detected in maternal urine samples, however, these metabolites were rarely detected in breast milk. Mono-2-ethylhexyl phthalate (MEHP), mono–n-butyl phthalate (MnBP), mono-ethyl phthalate (MEP), and MMP were detected in all breast milk samples and the majority of infant formula samples, however, no significant differences were found in infant urinary phthalate concentrations for breast-fed vs. bottle-fed infants. Finally, significant correlations were reported between MEHHP (r = 0.35), MEOHP (r = 0.35), and MEP (r = 0.37) metabolites in maternal urine at < 20 weeks and meconium levels. Correlations were also found between maternal and infant urine concentrations of MBzP (r = 0.78), MnBP (r = 0.40), MCPP (r = 0.41), and MEP (r = 0.56) at 2-3 months postpartum.

Overall results indicate that maternal and infant urine, as well as breast milk, contained detectable levels of various phthalate metabolites. By tracking phthalate concentrations from early pregnancy through to the post-natal period, the present study was able to demonstrate a correlation between maternal and infant phthalate exposure, particularly for MBzP levels in post-natal maternal urine and infant urine. Correlations between maternal urinary MEHHP, MEOHP, and MEP metabolites with meconium levels in infants also suggest evidence of maternal-fetal-transfer of phthalates. The present study benefits from the collection of various biospecimens from both infants and mothers (e.g., infant meconium, infant urine, breast milk, etc.) within the same cohort over multiple sampling periods. A primary limitation of the study relates to its relatively small sample size and the highly educated background of its study population, which may limit generalizability of results. Based on study findings, additional research is warranted on the utility of meconium as a measure of fetal exposure to phthalates.

Source: Arbuckle TE, Fisher M, MacPherson S, et al. Maternal and early life exposure to phthalates: The Plastics and Personal-Care Products use in Pregnancy (P4) study. Science of the Total Environment; 2016(551-552): 344-356. DOI: 10.1016/j.scitontenv.2016.02.022.

0048-9697/Crown Copyright © 2016 Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Posted September 30, 2019.

Click here to read the full text study.

Angeline A. De Leon, MA, graduated from the University of Illinois at Urbana-Champaign in 2010, completing a bachelor’s degree in psychology, with a concentration in neuroscience. She received her master’s degree from The Ohio State University in 2013, where she studied clinical neuroscience within an integrative health program. Her specialized area of research involves the complementary use of neuroimaging and neuropsychology-based methodologies to examine how lifestyle factors, such as physical activity and meditation, can influence brain plasticity and enhance overall connectivity.

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