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Urinary Concentrations of Phthalates in Couples Planning Pregnancy and Its Association with 8‑Hydroxy-2′-deoxyguanosine, a Biomarker of Oxidative Stress: Longitudinal Investigation of Fertility and the Environment Study
journal contribution
posted on 2015-12-17, 03:50 authored by Ying Guo, Jennifer Weck, Rajeswari Sundaram, Alexandra
E. Goldstone, Germaine Buck Louis, Kurunthachalam KannanOxidative
stress has been recognized as one of the most important
contributors to infertility in both males and females. Exposure to
many environmental chemicals, such as phthalates, has been shown to
induce oxidative stress. In a longitudinal study designed to assess
exposure to environmental chemicals and fecundity in couples who were
planning pregnancy, 894 urine samples were collected from 469 couples
from Michigan and Texas during 2005–2009. The concentrations
of 14 phthalate metabolites and a marker of oxidative stress, 8-hydroxy-2′-deoxyguanosine
(8-OHdG), were determined in these samples. Concentrations, profiles,
and estimated daily intakes (DIs) of phthalates were positively associated
with 8-OHdG. The median concentrations of monomethyl phthalate (mMP),
monoethyl phthalate (mEP), mono(3-carboxypropyl) phthalate (mCPP),
mono-n-butyl phthalate (mBP), mono(2-isobutyl) phthalate
(miBP), monobenzyl phthalate (mBzP), Σ5mEHP (sum
of five metabolites of di(2-ethylhexyl) phthalate (DEHP)) and Σ14phthalates (sum of 14 urinary phthalate metabolites) were
0.48, 85.2, 4.50, 7.66, 4.36, 3.80, 54.8, and 249 μg/g creatinine,
respectively. The estimated DI values for DEHP in 39 individuals were
above the U.S. Environmental Protection Agency’s (EPA) reference
dose (RfD) of 20 μg/kg-bw/day. The mean and median concentrations
of 8-OHdG were 6.02 and 3.13 μg/g creatinine, respectively,
which were significantly higher in females than in males. Statistically
significant associations were found between 8-OHdG and urinary concentrations
of mEP, and Σ5mEHP for females. Similarly, a significant
association was found between 8-OHdG and DIs estimated for select
phthalates. Our results suggested that phthalate exposure increases
oxidative stress, which can be a mechanism for the diminished fertility
observed in couples who were highly exposed to select phthalates.