Dataset Information

Association of urinary concentrations of phthalate metabolites with quinolinic acid among women: A potential link to neurological disorders.

ABSTRACT:

Background

Quinolinic acid (QA), a neuroactive metabolite produced during tryptophan degradation, is implicated in the pathogenesis of several neurological disorders. Phthalates are structurally similar to QA, and exposure to phthalates has demonstrated increased QA production and excretion in rodent studies. We recently showed that very high exposure to dibutyl phthalate was associated with higher concentrations of urinary QA in men. However, no human studies examined the associations between background (low) phthalate exposures and QA.

Objectives

To examine the associations of urinary concentrations of phthalate metabolites with QA.

Methods

Female participants (N = 126) who participated in a prospective cohort study at the Massachusetts General Hospital Fertility Center provided 758 urine samples (273 during pregnancy and 485 during non-pregnancy). Concentrations of 11 phthalate metabolites and QA in urine were measured. We used multivariable linear mixed effect models to estimate the percent change in urinary QA concentrations associated with a doubling (100%) of urinary phthalate metabolite concentration, and evaluated whether there was effect modification by pregnancy status.

Results

Women's mean (standard deviation) age was 34.2 (4.0) years with a body mass index of 23.5 (3.7) kg/m². The women were primarily Caucasian (92%), had at least a college degree (98%), and none were current smokers. Pairwise Spearman correlations between concentrations for phthalate metabolites and QA measured in the same urine samples ranged from 0.36 for MEHP to 0.68 for dibutyl phthalate (DBP) metabolites. In multivariable-adjusted models, the percent change in urinary QA concentrations was significantly higher for each doubling of several urinary phthalate metabolite concentrations. For example, each doubling of DBP metabolites was associated with a 13.7% (95%CI: 10.6, 16.9)% higher QA. Associations between the low molecular weight phthalate metabolites and QA were stronger among samples collected during pregnancy as compared to non-pregnancy samples from the same women.

Conclusions

Urinary concentrations of several phthalate metabolites were positively associated with QA among women. These findings, along with the known neurotoxicity of QA, warrant the need to examine whether QA concentrations may serve as a pathway for the adverse neurodevelopment outcomes found in children's health studies.

SUBMITTER: Nassan FL

PROVIDER: S-EPMC7136979 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:BackgroundPhthalates are ubiquitous endocrine disrupting chemicals present in a wide variety of consumer products. However, the personal characteristics associated with phthalate exposure are unclear.ObjectivesWe sought to describe personal, behavioral, and reproductive characteristics associated with phthalate metabolite concentrations in an ongoing study nested within the Women's Health Initiative (WHI).Materials and methodsWe measured thirteen phthalate metabolites in two or three archived urine samples collected in 1993-2001 from each of 1257 WHI participants (2991 observations). We fit multivariable generalized estimating equation models to predict urinary biomarker concentrations from personal, behavioral, and reproductive characteristics.ResultsOlder age was predictive of lower concentrations of monobenzyl phthalate (MBzP), mono-carboxyoctyl phthalate (MCOP), mono-3-carboxypropyl phthalate (MCPP), and the sum of di-n-butyl phthalate metabolites (ΣDBP). Phthalate metabolite concentrations varied by race/region, with generally higher concentrations observed among non-Whites and women from the West region. Higher neighborhood socioeconomic status predicted lower MBzP concentrations, and higher education predicted lower monoethyl phthalate (MEP) and higher concentrations of the sum of metabolites of di-isobutyl phthalate (ΣDiBP). Overweight/obesity predicted higher MBzP, MCOP, monocarboxynonyl phthalate (MCNP), MCPP, and the sum of metabolites of di(2-ethylhexyl) phthalate (ΣDEHP) and lower MEP concentrations. Alcohol consumption predicted higher concentrations of MEP and ΣDBP, while current smokers had higher ΣDBP concentrations. Better diet quality as assessed by Healthy Eating Index 2005 scores predicted lower concentrations of MBzP, ΣDiBP, and ΣDEHP.ConclusionFactors predictive of lower biomarker concentrations included increased age and healthy behaviors (e.g. lower alcohol intake, lower body mass index, not smoking, higher quality diet, and moderate physical activity). Racial group (generally higher among non-Whites) and geographic regions (generally higher in Northeast and West compared to South regions) also were predictive of phthalate biomarker concentrations.

Project description:Both bisphenol A (BPA) and phthalates are known endocrine-disrupting chemicals for which there is widespread general population exposure. Human exposure occurs through dietary and non-dietary routes. Although animal studies have suggested a potential role of these chemicals in obesity, evidence from human studies is sparse and inconsistent, and prospective evidence is lacking. This study evaluated urinary concentrations of BPA and major phthalate metabolites in relation to prospective weight change.The study population was from the controls in a prospective case-control study of type 2 diabetes in the Nurses' Health Study (NHS) and NHSII. A total of 977 participants provided first-morning-void urine samples in 1996-2002. Urinary concentrations of BPA and nine phthalate metabolites were measured using liquid chromatography-mass spectrometry. Body weights were self-reported at baseline and updated biennially thereafter for 10 years.On average, the women gained 2.09?kg (95% confidence interval (CI), -2.27 to 6.80?kg) during the 10-year follow-up. In multivariate analysis with adjustment of lifestyle and dietary factors, in comparison with women in the lowest quartile of BPA concentration, those in the highest quartile had 0.23?kg per year (95% CI, 0.07-0.38?kg per year) greater weight gain during the 10-year follow-up (P-trend=0.02). Several phthalate metabolites, including phthalic acid, MBzP and monobutyl phthalate, were also associated with faster prospective weight gain in a dose-response fashion (P-trend<0.01), whereas other phthalates metabolites, including MEP and monoethylhexyl phthalate, were not monotonically associated with body weight change.These data suggest urinary concentrations of BPA and certain individual phthalate metabolites that were associated with modestly greater weight gain in a dose-response fashion. These data are consistent with a potential role of BPA and phthalates in obesity, although more prospective data are needed to corroborate these observations.

Project description:BACKGROUND:Phthalates and phenols are suspected endocrine disrupting chemicals that may adversely impact fetal outcomes following in utero exposure. Understanding predictors of exposure to phthalates and phenols during the prenatal period is important. METHODS:We measured urinary concentrations of 15 phthalate metabolites and 11 phenols in 446 pregnant women enrolled in the Healthy Start pre-birth cohort. Creatinine-adjusted geometric means (GM) for each urinary biomarker were compared across categories of potential sociodemographic and dietary predictors. To assess the independent relationship between each significant food group predictor and biomarker we used multivariable models, adjusted for sociodemographic predictors. RESULTS:The phthalate metabolites with the highest concentrations were monoethyl phthalate (GM: 41.1µg/g creatinine) and monocarboxyisooctyl phthalate (GM: 20.5µg/g creatinine). Benzophenone-3 (GM: 124.6µg/g creatinine) and methyl paraben (GM: 119.9µg/g creatinine) were the phenols with the highest concentrations. Concentrations of the metabolites of di-n-butyl phthalate and di(2-ethylhexyl) phthalate were significantly higher in younger, unmarried or unemployed mothers, those who were overweight or obese, those with lower educational attainment, or those of minority race/ethnicity (p-values < 0.05). Metabolites of di-n-butyl phthalate concentrations were 18% lower in those who consumed milk ? 7 times per week (95% CI: 30-4%). Benzophenone-3 and triclosan concentrations were significantly higher in older, married, or employed mothers, those with normal body mass index, higher educational attainment, higher household income, or who were non-Hispanic white (p-values < 0.05). Benzophenone-3 concentrations were 62% higher in those who consumed seafood ? 5 times per month (95% CI: 16-127%). CONCLUSIONS:We observed differences in urinary concentrations of phthalates and phenol biomarkers by sociodemographic predictors in an ethnically diverse cohort of pregnant women. These results and future analyses from this prospective cohort will help inform targeted interventions to reduce exposure to these potential endocrine disrupting chemicals during pregnancy.

Project description:Study questionAre urinary phthalate metabolites associated with reduced antral follicle growth among women in an infertility setting?Summary answerHigher urinary concentrations of di(2-ethylhexyl) phthalate (DEHP) metabolites were associated with significant decreases in antral follicle count (AFC) among women seeking infertility care.What is known alreadyExperimental animal studies show that DEHP accelerates primordial follicle recruitment and inhibits antral follicle growth. Whether phthalates also reduce the growing antral follicle pool in humans remains unknown.Study design, size, durationWe examined the association between urinary phthalate metabolites and AFC using prospective data from 215 females recruited between 2004 and 2012 in the Environment and Reproductive Health (EARTH) study.Participants/materials, setting, methodsWe quantified the urinary concentrations of 11 phthalate metabolites. We estimated the geometric mean for all urine samples provided prior to unstimulated day 3 AFC assessment for each woman. We evaluated the association of AFC with ∑DEHP (molar sum of four DEHP metabolites) and individual phthalate metabolites using Poisson regression, adjusting for age, BMI and smoking.Main results and the role of chanceWe observed significant decreases in mean AFC for all higher quartiles of ∑DEHP as compared with the lowest quartile. Compared with women in the first quartile of ∑DEHP, women in the second, third and fourth quartiles had a -24% (95% confidence interval (CI): -32%, -16%), -19% (95% CI: -27%, -9%), and -14% (95% CI: -23%, -5%) decrease in mean AFC. The absolute mean AFC in the first quartile was 14.2 follicles (95% CI: 13.2, 15.2) compared with 10.7 follicles (95% CI: 9.9, 11.6) in the second quartile. We observed similar trends among the four individual DEHP metabolites. There was no consistent change in AFC among the remaining phthalate metabolite concentrations evaluated.Limitations, reasons for cautionWe demonstrated a negative association between DEHP and a well-established marker of ovarian reserve among a subfertile population. However these findings may not be generalizable to women without fertility concerns, and we cannot rule out co-exposure to other chemicals.Wider implications of the findingsEnvironmental chemicals that inhibit the size of the growing antral follicle pool can impair fertility and reduce fecundity. This study suggests evidence in need of further investigation on the impact of phthalates on the human oocyte and follicular development.Study funding/competing interestsWork supported by grants ES009718, ES022955, ES000002, and T32ES007069 from the National Institute of Environmental Health Sciences (NIEHS) and grant T32 DK007703-16 from the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). C.M. was supported by a post-doctoral training award from the Canadian Institutes of Health Research. There are no competing interests to declare.

Project description:BACKGROUND:Phthalates and bisphenol A (BPA) are environmental contaminants that may affect early embryonic development. OBJECTIVE:To assess the association between phthalate metabolites and BPA with early pregnancy endpoints in a cohort of women followed from before conception. METHODS:We quantified 11 phthalate metabolites and BPA in 137 conception cycles from naturally conceived clinical pregnancies. Phthalate metabolites and BPA concentrations were measured in a pooled sample of three daily morning urine specimens. Daily urinary hormone measurements had previously been used to define ovulation, implantation, and corpus luteum rescue. We assessed associations between conception cycle exposures (phthalate biomarkers and BPA) and 1) time from ovulation to implantation; 2) type of corpus luteum rescue (timing and pattern of rise in progesterone: early, late, or no rise); and 3) rate of initial rise in hCG. RESULTS:Mono(3-carboxypropyl) phthalate (MCPP) and mono-isobutyl phthalate (MiBP) were associated with earlier implantation (6-8 days vs. 9 days (the most commonly observed); per natural log-unit, OR (95% CI) =?2.8 (1.2, 6.7) and OR (CI) =?2.1 (1.2, 3.7), respectively). Monoethyl phthalate (MEP) was associated with later implantation (10-12 days vs. 9 days); OR (CI) =?1.5 (1.0, 2.1). Compared with implantation on day 9, BPA was significantly associated with both earlier and later implantation (OR=2.2 for both). Women with concentrations above the median of monobenzyl phthalate (MBzP) (p?=?0.04) or above the median of the molar sum of four di(2-ethylhexyl) phthalate metabolites (?DEHP) (p?=?0.08) had a slower initial rise in hCG. Increasing MCPP was associated with an increased odds of a late rise rescue (OR (CI) =?2.9 (1.0, 8.5); late rise vs. early rise), while increasing MEP was associated with a no rise rescue (OR (CI) =?1.6 (0.9, 2.8); no rise vs. early rise). CONCLUSIONS:The reported associations varied in their direction of effect, some potentially protective, others adverse. This may reflect the complexity with which these potential endocrine disrupting chemicals can be acting, but chance findings are also possible. Given that women continue to be exposed to these compounds (or their precursors), continued research on the effects they may have on pregnancy is warranted.