Low-level plasticizer exposure and all-cause and cardiovascular disease mortality in the general population

BACKGROUND

Plasticizers, also called phthalates, are a group of chemicals widely used in daily life. A previous report showed no significant association between phthalate metabolite concentrations and mortality. We investigated the association of urinary phthalate levels and individual phthalate metabolite levels with all-cause and cardiovascular disease (CVD) mortality after standardizing the phthalate concentration.

METHODS

A total of 6,625 participants were recruited from a nationally representative sample of adults aged 40 years or older who were enrolled in the National Health and Nutrition Examination Survey (NHANES) between 2003 and 2014 and were followed up through December 31, 2015. Data were analyzed from January 2021 to June 2021. NHANES-linked updated National Death Index public access files were used to acquire information on mortality status and cause of death. The present study conducted extended follow-up of an earlier analysis. Cox proportional hazard models were performed to calculate the hazard ratios (HRs) and 95% confidence intervals (CIs) of covariate-adjusted creatinine standardization urinary phthalate concentrations with all-cause and CVD mortality after adjusting for demographics, lifestyle factors and comorbidity variables.

RESULTS

The mean ± standard deviation age of all participants in the final study was 59.9±12.6 years old, and 49.6% of the participants were male. The median follow-up time was 73 months (range 1-157 months). At the censoring date of December 31, 2015, 3,023 participants were identified as deceased (13.4%). A fully adjusted Cox model showed that a urinary di(2-ethylhexyl) phthalate (DEHP) concentration >= 83.4 ng/mL was associated with a slight increase in all-cause mortality (HR 1.27, 95% CI 1.03, 1.57, P for trend= 0.014) and CVD mortality (HR 2.19, 95% CI 1.35, 3.54, P for trend= 0.002). Similarly, urinary mono-2-ethyl-5-carboxypentyl phthalate (MECPP) levels >= 39.2 ng/mL were associated with increased CVD mortality (HR 2.33, 95% CI 1.45, 3.73, P for trend < 0.001). Restricted cubic spline analyses suggested linear associations of DEHP and MECPP levels with all-cause and CVD mortality.

CONCLUSION

In this large nationally representative sample of American adults, high urinary DEHP and MECPP were significantly associated with all-cause and CVD mortality after adjusting for demographics, lifestyle factors and comorbidity variables.

Predictors of urinary bisphenol A and phthalate metabolite concentrations in Mexican children

Exposure to endocrine disrupting chemicals such as bisphenol A (BPA) and phthalates is prevalent among children and adolescents, but little is known regarding important sources of exposure at these sensitive life stages. In this study, we measured urinary concentrations of BPA and nine phthalate metabolites in 108 Mexican children aged 8-13 years. Associations of age, time of day, and questionnaire items on external environment, water use, and food container use with specific gravity-corrected urinary concentrations were assessed, as were questionnaire items concerning the use of 17 personal care products in the past 48-h. As a secondary aim, third trimester urinary concentrations were measured in 99 mothers of these children, and the relationship between specific gravity-corrected urinary concentrations at these two time points was explored. After adjusting for potential confounding by other personal care product use in the past 48-h, there were statistically significant (p<0.05) positive associations in boys for cologne/perfume use and monoethyl phthalate (MEP), mono(3-carboxypropyl) phthalate (MCPP), mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), and mono(2-ethyl-5-oxohexyl) phthalate (MEOHP), and in girls for colored cosmetics use and mono-n-butyl phthalate (MBP), mono(2-ethylhexyl) phthalate (MEHP), MEHHP, MEOHP, and mono(2-ethyl-5-carboxypentyl) phthalate (MECPP), conditioner use and MEP, deodorant use and MEP, and other hair products use and MBP. There was a statistically significant positive trend for the number of personal care products used in the past 48-h and log-MEP in girls. However, there were no statistically significant associations between the analytes and the other questionnaire items and there were no strong correlations between the analytes measured during the third trimester and at 8-13 years of age. We demonstrated that personal care product use is associated with exposure to multiple phthalates in children. Due to rapid development, children may be susceptible to impacts from exposure to endocrine disrupting chemicals; thus, reduced or delayed use of certain personal care products among children may be warranted.

Phthalates and risk of endometriosis

BACKGROUND

Phthalates are ubiquitous environmental chemicals with endocrine disruptive properties. The impact of these chemicals on endocrine-related disease in reproductive-age women is not well understood.

OBJECTIVE

To investigate the relationship between urinary phthalate metabolite concentrations and the risk of a hormonally-driven disease, endometriosis, in reproductive-age women.

METHODS

We used data from a population-based case-control study of endometriosis, conducted among female enrollees of a large healthcare system in the U.S. Pacific Northwest. We measured urinary phthalate metabolite concentrations on incident, surgically-confirmed cases (n=92) diagnosed between 1996 and 2001 and population-based controls (n=195). Odds ratios (OR), and 95% confidence intervals (CI) were estimated using unconditional logistic regression, adjusting for urinary creatinine concentrations, age, and reference year.

RESULTS

The majority of women in our study had detectable concentrations of phthalate metabolites. We observed a strong inverse association between urinary mono-(2-ethyl-5-hexyl) phthalate (MEHP) concentration and endometriosis risk, particularly when comparing the fourth and first MEHP quartiles (aOR 0.3, 95% CI: 0.1-0.7). Our data suggested an inverse association between endometriosis and urinary concentrations of other di-2-ethylhexyl phthalate (DEHP) metabolites (mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP)) and ∑DEHP, however, the confidence intervals include the null. Our data also suggested increased endometriosis risk with greater urinary concentrations of mono-benzyl phthalate (MBzP) and mono-ethyl phthalate (MEP), although the associations were not statistically significant.

CONCLUSIONS

Exposure to select phthalates is ubiquitous among female enrollees of a large healthcare system in the U.S. Pacific Northwest. The findings from our study suggest that phthalates may alter the risk of a hormonally-mediated disease among reproductive-age women.

Phthalates and the diets of U.S. children and adolescents

BACKGROUND

Di-2-ethylhexylphthalate (DEHP) is an ester of phthalic acid commonly found in processed foods. DEHP may contribute to obesity and insulin resistance in children and adolescents, yet dietary exposures have been not been studied in this vulnerable subpopulation.

OBJECTIVE

To assess diet and its relation to urinary phthalates in a nationally representative sample of US children and adolescents.

DESIGN

Cross-sectional analysis of 24-h dietary recall and urinary phthalate metabolites from 2743 6-19 year olds participating in the 2003-8 National Health and Nutrition Examination Surveys. Regression analyses examined relationships of food consumption with log-transformed metabolite concentrations, examined as low-molecular weight, high molecular weight and di-2-ethylhexylphthalate categories, controlling for urinary creatinine, age group, body mass index category, race/ethnicity, caloric intake and gender.

RESULTS

We identified a -0.04% (95% CI: -0.08, -0.01) increment in di-2-ethylhexylphthalate metabolite concentration/additional gram fruit consumption, a +0.01% increment/additional calorie dietary intake (95% CI: +0.003, +0.02), and a +0.09% (95% CI: +0.02, +0.17) increment/additional gram meat/poultry/fish consumption. Soy consumption (-0.40% increment/additional gram consumed, 95% CI: -0.66, -0.14) was inversely associated with di-2-ethylhexylphthalate, while poultry (+0.23% increment/additional gram consumed, 95% CI: +0.12, +0.35) was positively associated. Findings were robust to examination of metabolite concentrations per unit body mass index and weight, and inclusion of fasting time.

CONCLUSIONS

Diet contributes to urinary phthalate concentrations in children and adolescents. Further study is needed to examine the implications of di-2-ethylhexylphthalate exposure, especially earlier in life, when more permanent metabolic changes may occur.

Prenatal urinary phthalate metabolites levels and neurodevelopment in children at two and three years of age

BACKGROUND

Previous studies suggest that prenatal phthalate exposure affects neurodevelopment and behavior during the first years of life.

OBJECTIVES

To evaluate the effect of maternal urinary concentrations of phthalate metabolites during pregnancy on mental and psychomotor development in children 24-36 months of age.

METHODS

This analysis was conducted on the first three years of life among a subsample of 136 mother-child pairs from the ELEMENT cohort studies conducted in Mexico City. Maternal urine samples collected during the third trimester of pregnancy were analyzed for 9 phthalate metabolites: Mono-ethyl phthalate (MEP), Mono-n-butyl phthalate (MnBP), mono-isobutyl phthalate (MiBP), mono-benzyl phthalate (MBzP), Mono-3-carboxypropyl phthalate (MCPP), and four di-2-ethylhexyl phthalate (DEHP) metabolites [mono-2-ethylhexyl-phthalate (MEHP), mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP), and mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP)]. Among the 136 children, 135 (99.3%) completed the study period. Child neurodevelopment was assessed using mental and psychomotor development indexes (MDI and PDI) from a Bayley (BSID II) test at 24, 30, and 36 months of age. The effect of prenatal phthalate exposure on neurodevelopment was estimated using linear regression models for longitudinal data clustered at the individual level.

RESULTS

No significant associations were observed among all children combined, but differential effects by gender were found. Among girls, there was a negative association between MDI and DEHP metabolites MEHP (β=-2.11 [95% CI: -3.73, -0.49]), MEHHP (β=-1.89 [95% CI: -3.64, -0.15]), MEOHP (β=-1.80 [95% CI: -3.58, -0.03]) MECPP (β=-2.52 [95% CI: -4.44, -0.61]), and ΣDEHP (β=-3.41 [95% CI: -5.26, -1.55]); there was no significant effect among boys. Male PDI was positively related to MBzP (β=1.79 [95% CI: 0.14, 3.45]) and MCPP (β=1.64 [95% CI: 0.15, 3.12]); there was no significant effect on PDI among girls.

CONCLUSION

This study demonstrates that sex plays a role of an effect modifier in the association between prenatal phthalate exposure and neurodevelopment.

Urinary phthalates are associated with higher blood pressure in childhood

OBJECTIVE

To examine associations of urinary phthalate levels with blood pressure (BP) and serum triglyceride and lipoprotein levels in children.

STUDY DESIGN

We performed a cross-sectional analysis of a subsample of US children aged 6-19 years who participated in the National Health and Nutrition Examination Survey between 2003 and 2008. We quantified exposure to 3 families of phthalates--low molecular weight, high molecular weight and di-2-ethylhexylphthalate (DEHP)--based on molar concentration of urinary metabolites. We assessed descriptive, bivariate, and multivariate associations with BP and lipid levels.

RESULTS

Controlling for an array of sociodemographic and behavioral factors, as well as diet and body mass index, levels of metabolites of DEHP, a phthalate commonly found in processed foods, were associated with higher age-, sex-, and height-standardized BP. For each log unit (roughly 3-fold) increase in DEHP metabolites, a 0.041 SD unit increase in systolic BP z-score was identified (P = .047). Metabolites of low molecular weight phthalates commonly found in cosmetics and personal care products were not associated with BP. Phthalate metabolites were not associated with triglyceride levels, high-density lipoprotein level, or prehypertension.

CONCLUSIONS

Dietary phthalate exposure is associated with higher systolic BP in children and adolescents. Further work is needed to confirm these associations, as well as to evaluate opportunities for intervention.

Methylerythritol phosphate pathway to isoprenoids: kinetic modeling and in silico enzyme inhibitions in Plasmodium falciparum

The methylerythritol phosphate (MEP) pathway of Plasmodium falciparum (P. falciparum) has become an attractive target for anti-malarial drug discovery. This study describes a kinetic model of this pathway, its use in validating 1-deoxy-d-xylulose 5-phosphate reductoisomerase (DXR) as drug target from the systemic perspective, and additional target identification, using metabolic control analysis and in silico inhibition studies. In addition to DXR, 1-deoxy-d-xylulose 5-phosphate synthase (DXS) can be targeted because it is the first enzyme of the pathway and has the highest flux control coefficient followed by that of DXR. In silico inhibition of both enzymes caused large decrement in the pathway flux. An added advantage of targeting DXS is its influence on vitamin B1 and B6 biosynthesis. Two more potential targets, 2-C-methyl-d-erythritol 2,4-cyclodiphosphate synthase and 1-hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate synthase, were also identified. Their inhibition caused large accumulation of their substrates causing instability of the system. This study demonstrates that both types of enzyme targets, one acting via flux reduction and the other by metabolite accumulation, exist in P. falciparum MEP pathway. These groups of targets can be exploited for independent anti-malarial drugs.

Urinary excretion of phthalate metabolites, phenols and parabens in rural and urban Danish mother-child pairs

Some phthalates, parabens and phenols have shown adverse endocrine disrupting effects in animal studies and are also suspected to be involved in human reproductive problems. However, knowledge about exposure sources and biomonitoring data in different subsets of populations are still scarce. Thus, in this study first morning urine samples were collected from 6 to 11 years Danish children and their mothers. The content of seven parabens, nine phenols and metabolites of eight different phthalates were analysed by LC-MS/MS. Two parabens, six phenols and metabolites from six phthalate diesters were measurable in more than 50%, 75% and 90% of the participants, respectively. Thus the children and their mothers were generally exposed simultaneously to a range of phthalates, phenols and parabens. In general, the levels were low but for several of the compounds extreme creatinine adjusted concentrations 100-500-fold higher than the median level were seen in some participants. Children were significantly higher exposed to bisphenol A (BPA) and some of the phthalates (DiBP, DnBP, BBzP, DEHP and DiNP) than their mothers, whereas mothers were higher exposed to compounds related to cosmetics and personal care products such as parabens (MeP, EtP and n-PrP), benzophenone-3, triclosan and diethyl phthalate. However, a very high correlation between mothers and their children was observed for all chemicals. A high individual exposure to one chemical was often associated with a high exposure to other of the chemicals and the possibility of combination effects of multiple simultaneous exposures cannot be excluded.