Associations between organophosphate esters metabolites and sleep disorder and trouble sleeping in adults: a machine-learning approach

Organophosphate ester flame retardant chemicals and maternal depression during pregnancy

BACKGROUND

Depression substantially contributes to pregnancy-related morbidity, and pregnancy is increasingly recognized as a vulnerable window for exposure effects on maternal mental health. Exposures to organophosphate esters (OPEs) are ubiquitous and may have neurotoxic effects; however, their impacts on prenatal depression remain unknown. We evaluated associations of third trimester OPE metabolites on maternal depressive symptoms during pregnancy.

METHODS

This study included 422 participants in the Maternal and Developmental Risks from Environmental and Social Stressors (MADRES) cohort, a prospective pregnancy cohort of primarily low-income and Hispanic participants residing in Los Angeles, California. We measured concentrations of nine OPEs in third trimester spot urine samples (mean gestational age = 31.5 ± 2.0 weeks). Using the Center for Epidemiologic Studies-Depression (CES-D) scale, we classified participants as having probable depression during pregnancy (N = 137) or not (N = 285) if one or more CES-D scores administered at each trimester met the suggested cutoff score for clinically significant depressive symptoms (≥16). We estimated associations of prenatal OPE metabolite concentrations in tertiles and risk of prenatal depression using modified Log-Poisson regression. We examined associations of the OPE mixture on depression during pregnancy using Bayesian kernel machine regression (BKMR).

RESULTS

Participants with the highest tertiles of DPHP and BDCIPP exposure had a 67% (95% CI: 22%, 128%) and 47% (95% CI: 4%, 108%) increased risk of maternal depressive symptoms during pregnancy, respectively. No associations between other OPE metabolites and maternal depression symptoms were observed. In mixture analyses, we observed a positive and linear association between higher exposure to the OPE metabolite mixture and odds of prenatal maternal depression, primarily driven by DPHP.

CONCLUSIONS

Our findings provide new evidence of associations between frequently detected OPE metabolites on maternal depression symptoms during pregnancy. Results could inform future intervention efforts aimed at reducing perinatal maternal depression.

Association of serum individual and mixed aldehydes with depressive symptoms in the general population: A machine learning study

BACKGROUND

Humans have many opportunities to be exposed to aldehydes which have potential mechanisms for causing depression. We aimed to explore the relationships between serum individual and mixed aldehydes with depressive symptoms in general population.

METHODS

The data was extracted from the National Health and Nutrition Examination Survey 2013-2014. Depressive symptoms were assessed by Patient Health Questionnaire-9. Weighted binomial logistic regression and Bayesian kernel machine regression (BKMR) model were used to explore the association of six individual aldehyde and mixed aldehydes with depressive symptoms, respectively. Sex stratification analysis and sensitivity analysis were conducted.

RESULTS

A total of 701 participants were included. We found a positive association between the highest (Q4) versus lowest quartile (Q1) of butyraldehyde with depressive symptoms (OR: 2.86, 95 % CI: 1.22-6.68), and a negative association between the Q3 versus Q1 of benzaldehyde (0.21, 0.07-0.60) and isopentanaldehyde (0.28, 0.08-0.90) with depressive symptoms in multivariate-adjusted model. The mixed aldehydes were positively associated with depressive symptoms using BKMR model, and butyraldehyde and heptanaldehyde were the dominant aldehydes. Several aldehydes, such as butyraldehyde and benzaldehyde, interacted with each other in their effects on depressive symptoms. The results of gender stratification analysis showed that butyraldehyde was the major contributor to the total effect of aldehydes on depressive symptoms in males, while heptanaldehyde was the dominant aldehyde in females.

LIMITATIONS

Causality cannot be inferred in this cross-sectional study.

CONCLUSIONS

Our study indicated that mixed aldehydes can increase the risk of depressive symptoms, of which butyraldehyde and heptanaldehyde were the major contributing aldehydes.

Review on typical organophosphate diesters (di-OPEs) requiring priority attention: Formation, occurrence, toxicological, and epidemiological studies

The impact of primary metabolites of organophosphate triesters (tri-OPEs), namely, organophosphate diesters (di-OPEs), on the ecology, environment, and humans cannot be ignored. While extensive studies have been conducted on tri-OPEs, research on the environmental occurrence, toxicity, and health risks of di-OPEs is still in the preliminary stage. Understanding the current research status of di-OPEs is crucial for directing future investigations on the production, distribution, and risks associated with environmental organophosphate esters (OPEs). This paper specifically reviews the metabolization process from tri-OPEs to di-OPEs and the occurrence of di-OPEs in environmental media and organisms, proposes typical di-OPEs in different media, and classifies their toxicological and epidemiological findings. Through a comprehensive analysis, six di-OPEs were identified as typical di-OPEs that require prioritized research. These include di-n-butyl phosphate (DNBP), bis(2-butoxyethyl) phosphate (BBOEP), bis(1,3-dichloro-2-propyl) phosphate (BDCIPP), bis(2-chloroethyl) phosphate (BCEP), bis(1-chloro-2-propyl) phosphate (BCIPP), and diphenyl phosphate (DPHP). This review provides new insights for subsequent toxicological studies on these typical di-OPEs, aiming to improve our understanding of their current status and provide guidance and ideas for research on the toxicity and health risks of di-OPEs. Ultimately, this review aims to enhance the risk warning system of environmental OPEs.

Dose-response association of polycyclic aromatic hydrocarbon with self-reported trouble sleeping in adults: evidence from the National Health and Nutrition Examination Survey

Previous epidemiological evidence from large population-based studies on the association between polycyclic aromatic hydrocarbons (PAH) exposure and the risk of sleep disorders is inadequate. To comprehensively examine the relationship between independent and combined PAHs and trouble sleeping, we analyzed data from 8194 participants from the National Health and Nutrition Survey (NHANES) cycles. Multivariate adjusted logistic regression and restricted cubic spline models were applied to assess the relationship between PAH exposure and the risk of trouble sleeping. Bayesian kernel machine regression and weighted quantile sum regression models were used to estimate the combined association of urinary PAHs with trouble sleeping. In the single-exposure analyses, compared with the lowest level, the respective adjusted odds ratios (ORs) for trouble sleeping among subjects from the highest quartile were 1.34 (95% CI, 1.15, 1.56), 1.23 (95% CI, 1.05, 1.44), 1.31 (95% CI, 1.11, 1.54), 1.35 (95% CI, 1.15, 1.58), and 1.29 (95% CI, 1.08, 1.53) for 1-hydroxynaphthalene (1-NAP), 2-hydroxynaphthalene (2-NAP), 3-hydroxyfluorene (3-FLU), 2-hydroxyfluorene(2-FLU), and 1-hydroxypyrene(1-PYR). An overall positive correlation between the PAH mixture and trouble sleeping was observed when the mixture was at the 50th percentile or higher. The current study reveals that PAH metabolites (1-NAP, 2-NAP, 3-FLU, 2-FLU, and 1-PYR) may be detrimental to trouble sleeping. PAH mixture exposure was positively associated with trouble sleeping. The results suggested the potential impacts of PAHs and expressed concerns regarding the potential impact of PAHs on health. More intensive research and monitoring of environmental pollutants in the future will contribute to preventing environmental hazards.

Human exposure to organophosphate esters in water and packed beverages

Drinks are an essential part of human diet, which makes them a source of human exposure to plasticizers such as organophosphate esters (OPEs). The current study provides new information about sixteen OPE levels in 75 different samples (tap water, packed water, cola drinks, juice, wine and hot drinks). Tap water mean levels (40.9 ng/L) were statistically higher than packed water mean levels (4.82 ng/L), mainly due to the contribution of tris(2-chloroisopropyl) phosphate (TCIPP) and tris(2-butoxyethyl) phosphate (TBOEP) that may come from PVC water pipes. Over 90% of samples presented at least one OPE, where regular cola drinks had the highest mean concentrations (2876 ng/L). There was a significantly higher presence of OPEs in added sugar beverages than sugar free drinks, especially for 2-ethylhexyl diphenyl phosphate (EHDPP), which might be related not only to packaging materials but to the added sugar content. Estimated daily intakes (EDIs) in normal and high-exposure scenarios were 2.52 ng/kg bw/day and 7.43 ng/kg bw/day, respectively. Human risk associated with beverages ingestion showed regular cola drinks, juice and tap water as the groups with the highest hazard quotients (HQs). Although OPE exposure was below to safety limits, it should be noted that EHDPP values for regular cola group must be cause of concern, and other routes of exposure such as food ingestion or air inhalation should be also considered.

Prenatal exposure to organophosphate esters is associated with decreased anogenital distance in offspring

BACKGROUND

Evidence from in vitro and rodent studies suggests that organophosphate esters (OPEs) may disrupt sex steroid hormone homeostasis, but no human studies, to date, have examined the effects of in utero exposure to OPEs on offspring reproductive development.

OBJECTIVE

Anogenital distance (AGD) is a sensitive biomarker of fetal hormonal milieu and has been used to assess reproductive toxicity. We evaluated the longitudinal effects of prenatal exposure to OPEs on the AGD of offspring from birth to 4 years.

METHODS

Based on Shanghai-Minhang Birth Cohort Study, pregnant women provided urine samples at a gestational age of 12-16 weeks, which were analyzed for eight OPE metabolites. AGD was measured in offspring at birth and 0.5, 1, and 4 years of age. We used generalized estimating equations (GEE) and Bayesian kernel machine regression (BKMR) models to estimate the associations of prenatal exposure to individual OPE metabolites and OPE mixtures with AGD stratified by sex.

RESULTS

A total of 733 mother-infant pairs were analyzed. Prenatal exposure to diphenyl phosphate and bis-(2-ethylhexyl) phosphate was associated with decreased AGD in boys in GEE models. Bis-(1-chloro-2-propyl) phosphate (BCIPP) showed a similar but marginally significant effect. Prenatal exposure to most OPE metabolites was associated with decreased AGD in girls, with the most profound association observed for bis (2-butoxyethyl) phosphate (BBOEP) and alkyl-OPEs. The OPE mixture was also inversely associated with AGD in both sexes. The single-exposure effects of BKMR models were largely consistent with those observed in the GEE models. In addition, alkyl-OPEs, particularly BBOEP, contributed the most to the decreased AGD in girls, while BCIPP contributed the most to the decreased AGD in boys.

CONCLUSIONS

This study provides the first human evidence that prenatal exposure to OPEs is associated with decreased AGD in offspring. The magnitude of these effects may vary depending on the structure of OPEs.