Identifying Vulnerable Periods of Neurotoxicity to Triclosan Exposure in Children

Environmental phenol exposures in 6- to 12-week-old infants: The Infant Feeding and Early Development (IFED) study

BACKGROUND

Exposure to phenols, endocrine-disrupting chemicals used in personal care and consumer products, is widespread. Data on infant exposures are limited despite heightened sensitivity to endocrine disruption during this developmental period. We aimed to describe distributions and predictors of urinary phenol concentrations among U.S. infants ages 6-12 weeks.

METHODS

The Infant Feeding and Early Development (IFED) study is a prospective cohort study of healthy term infants enrolled during 2010-2013 in the Philadelphia region. We measured concentrations of seven phenols in 352 urine samples collected during the 6- or 8- and/or 12-week study visits from 199 infants. We used linear mixed models to estimate associations of maternal, sociodemographic, infant, and sample characteristics with natural-log transformed, creatinine-standardized phenol concentrations and present results as mean percent change from the reference level.

RESULTS

Median concentrations (μg/L) were 311 for methylparaben, 10.3 for propylparaben, 3.6 for benzophenone-3, 2.1 for triclosan, 1.0 for 2,5-dichlorophenol, 0.7 for BPA, and 0.3 for 2,4-dichlorophenol. Geometric mean methylparaben concentrations were approximately 10 times higher than published estimates for U.S. children ages 3-5 and 6-11 years, while propylparaben concentrations were 3-4 times higher. Infants of Black mothers had higher concentrations of BPA (83%), methylparaben (121%), propylparaben (218%), and 2,5-dichorophenol (287%) and lower concentrations of benzophenone-3 (-77%) and triclosan (-53%) than infants of White mothers. Triclosan concentrations were higher in breastfed infants (176%) and lower in infants whose mothers had a high school education or less (-62%). Phenol concentrations were generally higher in summer samples.

CONCLUSIONS

Widespread exposure to select environmental phenols among this cohort of healthy U.S. infants, including much higher paraben concentrations compared to those reported for U.S. children, supports the importance of expanding population-based biomonitoring programs to infants and toddlers. Future investigation of exposure sources is warranted to identify opportunities to minimize exposures during these sensitive periods of development.

Time-varying associations of gestational and childhood triclosan with pubertal and adrenarchal outcomes in early adolescence

Background

Triclosan is an endocrine-disrupting chemical, but associations with pubertal outcomes remain unclear. We examined associations of gestational and childhood triclosan with adolescent hormone concentrations and pubertal stage.

Methods

We quantified urinary triclosan concentrations twice during pregnancy and seven times between birth and 12 years in participants recruited from Cincinnati, OH (2003-2006). We averaged concentrations across pregnancy and childhood and separately considered individual exposure periods in multiple informant models. At 12 years, we measured serum hormone concentrations (males [n = 72] and females [n = 84]-dehydroepiandrosterone-sulfate, luteinizing hormone, follicle-stimulating hormone; males-testosterone; females-estradiol). Also at age 12 years, participants self-reported physical development and menarchal timing. We estimated associations (95% confidence interval) of triclosan with hormone concentrations, more advanced physical development, and age at menarche.

Results

For females, each doubling of childhood triclosan was associated with 16% lower estradiol concentrations (-29%, 0%), with stronger associations for measures closer to adolescence. We found suggestive evidence that higher triclosan at any age was associated with ~10% (for gestational triclosan: -18%, -2%) lower follicle-stimulating hormone concentrations among males and early postnatal (1-3 years) triclosan was associated with 63% (5%, 96%) lower odds of advanced pubic hair development in females. In multiple informant models, each doubling of gestational triclosan concentrations was associated with 5% (0%, 9%) earlier age at menarche, equivalent to 5.5 months.

Conclusion

Gestational and childhood triclosan concentrations were related to some pubertal outcomes including hormone concentrations and age at menarche. Our findings highlight the relevance of elucidating potential sex-specific and time-dependent actions of triclosan.

Conceptualizing the Role of the Microbiome as a Mediator and Modifier in Environmental Health Studies: A Scoping Review of Studies of Triclosan and the Microbiome

PURPOSE OF REVIEW

Triclosan is an endocrine-disrupting antimicrobial additive that is suspected of contributing to antibiotic resistance and altering the microbiome. In this scoping review, we summarize what is known about the association between triclosan exposure and the microbiome using evidence from in vivo and epidemiologic studies.

RECENT FINDINGS

Our review includes 11 rodent studies, seven fish studies, and five human studies. Evidence from animal studies suggests that triclosan decreases the diversity of the microbiome, although only one epidemiologic study agreed. Most studies suggest that triclosan alters the microbial community beta diversity, but disagree on which taxa contributed to compositional differences. Taxa in the Bacteroidetes, Firmicutes, and Proteobacteria may be more influenced by triclosan than those in other phyla. Studies on triclosan and the microbiome were scarce and were inconclusive as to the effects of triclosan on the microbiome. Additional research is needed to clarify windows of heightened susceptibility of the microbiome to triclosan. We recommend guidelines for future microbiome research in environmental health to increase comparability across studies.

Disruption of phosphofructokinase activity and aerobic glycolysis in human bronchial epithelial cells by atmospheric ultrafine particulate matter

Exposure to ambient ultrafine particulate matter (UPM) causes respiratory disorders; however, the underlying molecular mechanisms remain unclear. In this study, we synthesized simulated UPM (sUPM) with controlled physicochemical properties using the spark-discharge method. Subsequently, we investigated the biological effects of sUPM using BEAS-2B human bronchial epithelial cells (HBECs) and a mouse intratracheal instillation model. High throughput RNA-sequencing and bioinformatics analyses revealed that dysregulation of the glycolytic metabolism is involved in the inhibited proliferation and survival of HBECs by sUPM treatment. Furthermore, signaling pathway and enzymatic analyses showed that the treatment of BEAS-2B cells with sUPM induces the inactivation of extracellular signal-regulated kinase (ERK) and protein kinase B (PKB, also known as AKT), resulting in the downregulation of phosphofructokinase 2 (PFK2) S483 phosphorylation, PFK enzyme activity, and aerobic glycolysis in HBECs in an oxidative stress-independent manner. Additionally, intratracheal instillation of sUPM reduced the phosphorylation of ERK, AKT, and PFK2, decreased proliferation, and increased the apoptosis of bronchial epithelial cells in mice. The findings of this study imply that UPM induces pulmonary toxicity by disrupting aerobic glycolytic metabolism in lung epithelial cells, which can provide novel insights into the toxicity mechanisms of UPM and strategies to prevent their toxic effects.

Early-Life Exposure to a Mixture of Phenols and Phthalates in Relation to Child Social Behavior: Applying an Evidence-Based Prioritization to a Cohort with Improved Exposure Assessment

BACKGROUND

Previous studies aiming at relating exposure to phenols and phthalates with child social behavior characterized exposure using one or a few spot urine samples, resulting in substantial exposure misclassification. Moreover, early infancy exposure was rarely studied.

OBJECTIVES

We aimed to examine the associations of phthalates and phenols with child social behavior in a cohort with improved exposure assessment and to a priori identify the chemicals supported by a higher weight of evidence.

METHODS

Among 406 mother-child pairs from the French Assessment of Air Pollution exposure during Pregnancy and Effect on Health (SEPAGES) cohort, 25 phenols/phthalate metabolites were measured in within-subject pools of repeated urine samples collected at the second and third pregnancy trimesters (∼ 21 samples/trimester) and at 2 months and 1-year of age (∼ 7 samples/period). Social behavior was parent-reported at 3 years of age of the child using the Social Responsiveness Scale (SRS). A structured literature review of the animal and human evidence was performed to prioritize the measured phthalates/phenols based on their likelihood to affect social behavior. Both adjusted linear regression and Bayesian Weighted Quantile Sum (BWQS) regression models were fitted. False discovery rate (FDR) correction was applied only to nonprioritized chemicals.

RESULTS

Prioritized compounds included bisphenol A, bisphenol S, triclosan (TCS), diethyl-hexyl phthalate (Σ DEHP ), mono-ethyl phthalate (MEP), mono-n -butyl phthalate (MnBP), and mono-benzyl phthalate (MBzP). With the exception of bisphenols, which showed a mixed pattern of positive and negative associations in pregnant mothers and neonates, few prenatal associations were observed. Most associations were observed with prioritized chemicals measured in 1-y-old infants: Each doubling in urinary TCS (β = 0.78 ; 95% CI: 0.00, 1.55) and MEP (β = 0.92 ; 95% CI: - 0.11 , 1.96) concentrations were associated with worse total SRS scores, whereas MnBP and Σ DEHP were associated with worse Social Awareness (β = 0.25 ; 95% CI: 0.01, 0.50) and Social Communication (β = 0.43 ; 95% CI: - 0.02 , 0.89) scores, respectively. BWQS also suggested worse total SRS [Beta  1 = 1.38 ; 95% credible interval (CrI): - 0.18 , 2.97], Social Awareness (Beta  1 = 0.37 ; 95% CrI: 0.06, 0.70), and Social Communication (Beta  1 = 0.91 ; 95% CrI: 0.31, 1.53) scores per quartile increase in the mixture of prioritized compounds assessed in 1-y-old infants. The few associations observed with nonprioritized chemicals did not remain after FDR correction, with the exception of benzophenone-3 exposure in 1-y-old infants, which was suggestively associated with worse Social Communication scores (corrected p = 0.07 ).

DISCUSSION

The literature search allowed us to adapt our statistical analysis according to the weight of evidence and create a corpus of experimental and epidemiological knowledge to better interpret our findings. Early infancy appears to be a sensitive exposure window that should be further investigated. https://doi.org/10.1289/EHP11798.

A pilot study of several environmental endocrine disrupting chemicals in children with autism spectrum disorder in south China

Autism spectrum disorders (ASD) is a group of heterogeneous neurodevelopmental disorders. Evidence has implied that environmental pollutants are important factors related to ASD. In this study, several environmental endocrine-disrupting chemicals, including parabens, benzophenone-type ultraviolet filters, hydroxyl polycyclic aromatic hydrocarbons, triclosan and tetrabromobisphenol A were analyzed in blood plasma in ASD children (n = 34) and the control children (n = 28). The results showed that parabens were the most concentrated chemicals (2.18 ng/mL, median value), followed by hydroxyl polycyclic aromatic hydrocarbons (0.73 ng/mL), benzophenone-type ultraviolet filters (0.14 ng/mL), triclosan (0.13 ng/mL) and tetrabromobisphenol A (0.03 ng/mL). ASD children accumulated significantly lower 2-hydroxy-4-methoxybenzophenone, 2,4-dihydroxybenzophenone, 4-hydroxybenzophenone and triclosan but higher 2-hydroxyphenanthrene and tetrabromobisphenol A than the control children (0.02/0.09 ng/mL of 2-hydroxy-4-methoxybenzophenone, p < 0.05; 0.04/0.07 ng/mL of 2,4-dihydroxybenzophenone, p < 0.05; 0.03/0.04 ng/mL of 4-hydroxybenzophenone, p < 0.05; 0.13/1.22 ng/mL of triclosan, p < 0.01; 0.03 ng/mL/not detected of 2-hydroxyphenanthrene, p < 0.05; 0.03/0.004 ng/mL of tetrabromobisphenol A, p < 0.05). Gender differences in certain environmental endocrine-disrupting chemicals were evident, and the differences were more inclined toward boys. Positive associations between 2-hydroxy-4-methoxybenzophenone and triclosan, and tetrabromobisphenol A and 2-hydroxyphenanthrene were found in ASD boys. Binary logistic regression analysis showed that the adjusted odds ratio value of 2-hydroxyphenanthrene in ASD boys was 11.0 (1.45-84.0, p < 0.05). This is the first pilot study on multiple environmental endocrine-disrupting chemicals in children with ASD in China.

The impact of correlated exposures and missing data on multiple informant models used to identify critical exposure windows

There has been heightened interest in identifying critical windows of exposure for adverse health outcomes; that is, time points during which exposures have the greatest impact on a person's health. Multiple informant models implemented using generalized estimating equations (MIM GEEs) have been applied to address this research question because they enable statistical comparisons of differences in associations across exposure windows. As interest rises in using MIMs, the feasibility and appropriateness of their application under settings of correlated exposures and partially missing exposure measurements requires further examination. We evaluated the impact of correlation between exposure measurements and missing exposure data on the power and differences in association estimated by the MIM GEE and an inverse probability weighted extension to account for informatively missing exposures. We assessed these operating characteristics under a variety of correlation structures, sample sizes, and missing data mechanisms considering various exposure-outcome scenarios. We showed that applying MIM GEEs maintains higher power when there is a single critical window of exposure and exposure measures are not highly correlated, but may result in low power and bias under other settings. We applied these methods to a study of pregnant women living with HIV to explore differences in association between trimester-specific viral load and infant neurodevelopment.

Associations of early life phthalate exposures with adolescent lipid levels and insulin resistance: The HOME Study

BACKGROUND

Early-life phthalate exposures may disrupt metabolic processes; however few prospective studies have assessed whether these associations extend to cardiometabolic outcomes during adolescence.

METHODS

Among 183 mother-adolescent pairs in a prospective cohort study that enrolled pregnant women in Cincinnati, OH (2003-2006), we quantified nine phthalate metabolites in spot urine samples collected twice from mothers during pregnancy and up to seven times from children. At age 12 years, we assessed triglycerides, high-density (HDL) and low-density (LDL) lipoprotein cholesterol, insulin, and glucose from fasting serum samples and calculated homeostatic model assessment of insulin resistance (HOMA-IR). Using multiple informant models, we estimated covariate-adjusted associations between urinary phthalate concentrations at each time period and cardiometabolic biomarkers at age 12 years, including modification by child sex.

RESULTS

Although most associations were weak or null, monoethyl phthalate (MEP), mono-n-butyl phthalate (MnBP), mono-isobutyl phthalate (MiBP), and monobenzyl phthalate (MBzP) concentrations were generally associated with lower LDL at age 12 years. A 10-fold increase in 4- and 12-year MEP was associated with -15.3 mg/dL (95% CI: 27.5, -3.13 mg/dL) and -11.8 mg/dL (-22.0, -1.51 mg/dL) lower LDL, respectively. Discrepant associations were observed in females versus males: a 10-fold increase in 3-year MEP concentrations was associated with 12.0 mg/dL (95% CI: 7.11, 31.1 mg/dL) higher LDL levels in males and -30.4 mg/dL (95% CI: 50.9, -9.8 mg/dL) lower LDL levels in females. Some urinary phthalate concentrations were cross-sectionally associated with HOMA-IR.

CONCLUSIONS

Early-life phthalate biomarker concentrations may be inversely associated with LDL during early adolescence in an exposure-period and sex-dependent manner.

Neurotoxic mechanisms of triclosan: The antimicrobial agent emerging as a toxicant

Several scientific studies have suggested a link between increased exposure to pollutants and a rise in the number of neurodegenerative disorders of unknown origin. Notably, triclosan (an antimicrobial agent) is used in concentrations ranging from 0.3% to 1% in various consumer products. Recent studies have also highlighted triclosan as an emerging toxic pollutant due to its increasing global use. However, a definitive link is missing to associate the rising use of triclosan and the growing number of neurodegenerative disorders or neurotoxicity. In this article, we present systematic scientific evidence which are otherwise scattered to suggest that triclosan can indeed induce neurotoxic effects, especially in vertebrate organisms including humans. Mechanistically, triclosan affected important developmental and differentiation genes, structural genes, genes for signaling receptors and genes for neurotransmitter controlling enzymes. Triclosan-induced oxidative stress impacting cellular proteins and homeostasis which triggers apoptosis. Though the scientific evidence collated in this article unequivocally indicates that triclosan can cause neurotoxicity, further epidemiological studies may be needed to confirm the effects on humans.

Early life exposure to triclosan from antimicrobial daily necessities may increase the potential risk of autism spectrum disorder: A multicenter study in China

BACKGROUND

Autism spectrum disorders (ASD) are a group of complex neurodevelopmental disorders with unclear etiologies. Our recent work indicated that maternal exposure to triclosan (TCS) significantly increased the autistic-like behavior in rats, possibly through disrupting neuronal retinoic acid signaling. Although environmental endocrine disruptors (EEDs) have been associated with autism in humans, the relationship between TCS, one of the EEDs found in antibacterial daily necessities, and autism has received little attention.

OBJECTIVE

The aims of this multicenter study were to evaluate TCS concentrations in typically developing (TD) children and ASD children, and to determine the relationship between TCS levels and the core symptoms of ASD children.

METHODS

A total of 1345 children with ASD and 1183 TD children were enrolled from 13 cities in China. Ages ranged between 2 and 7 years. A questionnaire was used to investigate the maternal use of antibacterial daily necessities (UADN) during pregnancy. The core symptoms of ASD were evaluated using the Autism Behavior Checklist (ABC), Childhood Autism Rating Scale (CARS), Social Response Scale (SRS), and the Children Neuropsychological and Behavior Scale-Revision 2016 (CNBS-R2016). The TCS concentration was measured using LC-MS/MS.

RESULTS

Maternal UADN during pregnancy may be an unrecognized potential environmental risk factor for ASD (OR=1.267, P = 0.023). Maternal UADN during pregnancy strongly correlated with TCS levels in the offspring (Adjusted β = 0.277, P < 0.001). TCS concentration was higher in ASD children (P = 0.005), and positively correlated with ABC (Sensory subscales: P = 0.03; Social self-help subscales: P = 0.011) and SRS scale scores (Social awareness subscales: P = 0.045; Social communication subscales: P = 0.001; Autism behavior mannerisms subscales: P = 0.006; SRS total score: P = 0.003) in ASD children. This association was more pronounced in boys than in girls.

CONCLUSION

To our knowledge, this is the first case-control study to examine the correlation between TCS and ASD. Our results suggest that maternal UADN during pregnancy may be a potential risk of ASD in offspring. Further detection of TCS levels showed that maternal UADN during pregnancy may be associated with excessive TCS exposure. In addition, the level of TCS in children with ASD is higher than TD children. The higher levels of TCS in children with ASD may be significantly associated with more pronounced core symptoms, and this association was more significant in male children with ASD.

Effect of Maternal Triclosan Exposure on Neonatal Thyroid-Stimulating Hormone Levels: A Cross-Sectional Study

Objective

This study is aimed at assessing the relationship between maternal urinary triclosan (uTCS) exposure and the thyroid-stimulating hormone (TSH) level of infant cord blood.

Methods

This cross-sectional study was carried out in 2019-2020 in Isfahan, Iran, and 99 pregnant women participated in the study. Urine samples were collected after the 28th week of pregnancy, and the concentration of TCS was measured using GC/MS. The cord blood levels of TSH (CBL-TSH) were measured. The association between uTCS and CBL-TSH was examined based on the general linear model.

Results

TCS was detected (≥0.01 ng/mL) in 100% of the urine samples, with the interquartile range (25%-75%) of uTCS levels 0.6-6.23 μg/g Cr. uTCS was not associated with CBL-TSH after adjustment for covariates. A significant relationship was observed between CBL-TSH of neonates born to mothers who had given birth only once compared to mothers who had given birth twice or more times.

Conclusions

Maternal exposure to TCS did not affect the infant CBL-TSH. However, the high concentrations of TCS in maternal urinary samples indicate the necessity of more precise regulations to decrease the use of this chemical in the industry and increase public awareness about using TCS-free compounds.

Gestational and childhood phthalate exposures and adolescent body composition: The HOME study

BACKGROUND

Early life phthalate exposures may disrupt metabolism but results from human studies are inconsistent and few have examined body composition during adolescence. We investigated associations of gestational and childhood urinary phthalate biomarker concentrations with body composition at age 12 years.

METHODS

We used data from 206 mother-child pairs in a prospective pregnancy and birth cohort enrolled in Cincinnati, OH from 2003 to 2006. We measured nine phthalate metabolites in spot urine samples collected twice from mothers during pregnancy and up to seven times from children at 1, 2, 3, 4, 5, 8, and 12 years. At age 12 years, we assessed fat and lean mass of the whole body and android and gynoid subregions, and visceral fat area with dual x-ray absorptiometry, and calculated android to gynoid %fat ratio and age- and sex-standardized fat and lean mass index z-scores. Using a multiple informant model, we estimated covariate-adjusted associations between urinary phthalate biomarker concentrations at each time period and outcomes at age 12 years. We assessed effect measure modification by child sex using stratified models.

RESULTS

Generally, urinary mono-benzyl phthalate (MBzP) concentrations were modestly associated with lower fat and lean mass. Each 10-fold increase in urinary MBzP concentrations during gestation and at ages 5 and 8 years was associated with a -0.34 (95%CI: -0.72, 0.05), -0.44 (95% CI: -0.83, -0.05), and -0.35 (95% CI: -0.71, 0.00) z-score difference in lean body mass index, respectively. Urinary monoethyl phthalate, mono-(3-carboxypropyl) phthalate, and summed di(2-ethylhexyl) phthalate metabolites were associated with greater lean mass at some exposure periods. Slightly weaker but similar patterns of association were found with other body composition measures; associations did not differ by child sex.

CONCLUSION

While most associations were weak, exposure to certain phthalates during gestation and childhood may be associated with adolescent body composition, particularly lean mass.

Association between triclosan exposure and obesity measures among 7-year-old children in northern China

BACKGROUND

Triclosan (TCS) is a widely used synthetic antibacterial compound with ubiquitous human exposure. Animal studies have suggested the obesogenic effect of TCS exposure, but knowledge regarding its impacts on childhood obesity was limited.

OBJECTIVE

To investigate the associations of TCS exposure with childhood obesity in northern China.

METHODS

This study included 423 children who participated in the 7-year-old follow-up visits of Laizhou Wan Birth Cohort in Shandong, northern China. Children's TCS exposure were determined in spot urine samples via high performance liquid chromatography-tandem mass. Their height, weight, waist circumference, body fat percentage, body mass index (BMI), and waist-to-height ratio (WHtR) were measured or calculated. BMI z-score ≥ 85th percentile was defined as overweight/obesity, and WHtR ≥ 0.5 was considered to be abdominal obesity. Multivariable linear regressions, generalized linear models (GLMs), and multivariable logistic regressions were performed to examine the associations between TCS exposure and obesity measures in children.

RESULTS

Linear regressions showed that TCS concentrations, when treated as continuous variables, were positively associated with BMI z-score (β = 0.12, 95% CI: 0.01, 0.24) and body fat percentage (β = 0.82, 95% CI: 0.13, 1.52). When TCS concentrations were categorized as a four-level ordinal variable, the results of GLMs were similar those of continuous variables and both of the positive trends were significant (p-trend = 0.049 for BMI z-score; p-trend = 0.023 for body fat percentage). Moreover, the higher TCS levels versus reference group were associated with an approximate 2-3 fold increased risk of abdominal obesity (p-trend = 0.044).

CONCLUSION

Exposure to TCS was positively associated with obesity measures among 7-year-old children in northern, China. Given to the cross-sectional study design, a large prospective study is warranted to confirm our findings.

Triclosan: A Small Molecule with Controversial Roles

Triclosan (TCS), a broad-spectrum antimicrobial agent, has been widely used in personal care products, medical products, plastic cutting boards, and food storage containers. Colgate Total^® toothpaste, containing 10 mM TCS, is effective in controlling biofilm formation and maintaining gingival health. Given its broad usage, TCS is present ubiquitously in the environment. Given its strong lipophilicity and accumulation ability in organisms, it is potentially harmful to biohealth. Several reports suggest the toxicity of this compound, which is inserted in the class of endocrine disrupting chemicals (EDCs). In September 2016, TCS was banned by the U.S. Food and Drug Administration (FDA) and the European Union in soap products. Despite these problems, its application in personal care products within certain limits is still allowed. Today, it is still unclear whether TCS is truly toxic to mammals and the adverse effects of continuous, long-term, and low concentration exposure remain unknown. Indeed, some recent reports suggest the use of TCS as a repositioned drug for cancer treatment and cutaneous leishmaniasis. In this scenario it is necessary to investigate the advantages and disadvantages of TCS, to understand whether its use is advisable or not. This review intends to highlight the pros and cons that are associated with the use of TCS in humans.

Variability of Urinary Concentrations of Phenols, Parabens, and Triclocarban during Pregnancy in First Morning Voids and Pooled Samples

Urinary concentrations of phenols, parabens, and triclocarban have been extensively used as biomarkers of exposure. However, because these compounds are quickly metabolized and excreted in urine, characterizing participants' long-term average exposure from a few spot samples is challenging. To examine the variability of urinary concentrations of these compounds during pregnancy, we quantified four phenols, four parabens, and triclocarban in 357 first morning voids (FMVs) and 203 pooled samples collected during the second and third trimesters of 173 pregnancies. We computed intraclass correlation coefficients (ICCs) by the sample type (FMV and pool) across two trimesters and by the number of composite samples in pools, ranging from 2 to 4, within the same trimester. Among the three compounds detected in more than 50% of the samples, the ICCs across two trimesters were higher in pools (0.29-0.68) than in FMVs (0.17-0.52) and the highest ICC within the same trimester was observed when pooling either two or three composites. Methyl paraben and propyl paraben primarily exposed via cosmetic use had approximately 2-3 times higher ICCs than bisphenol A primarily exposed via diet. Our findings support that within-subject pooling of biospecimens can increase the reproducibility of pregnant women's exposure to these compounds and thus could potentially minimize exposure misclassification.

Gestational triclosan exposure and infant birth weight: A systematic review and meta-analysis

BACKGROUND

Exposure to triclosan, an antimicrobial chemical used in some personal care and cleaning products, has been associated with reduced birth weight in some, but not all epidemiological studies.

OBJECTIVES

We conducted a systematic review and meta-analysis to characterize the relation of gestational triclosan exposure with infant birth weight and identify sources of heterogeneity between studies.

METHODS

We identified original studies measuring urinary triclosan concentrations during pregnancy and reporting their association with infant birth weight, gestational age (GA) adjusted birth weight (g), or GA-standardized birth weight z-scores. Using a random effects model, we estimated differences in these outcomes per 10-fold increase in triclosan concentrations and considered triclosan levels and infant sex as sources of heterogeneity. Using Navigation Guide Methods, we evaluated risk of bias within individual studies and across the body of evidence.

RESULTS

Among thirteen studies, median triclosan concentrations varied by almost 2-orders of magnitude (0.6-29 ng/mL), with higher concentrations in North American and some European studies compared to Asian ones. Associations between triclosan and birth weight (β:-20 g; 95% CI:-65, 26; n = 6) were stronger than those for GA-adjusted birth weight (β:-12 g; 95% CI:-29, 5; n = 9). Triclosan was not associated with GA-standardized birth weight z-scores (β:-0.04; 95% CI:-0.16, 0.07; n = 5). The association between triclosan and GA-adjusted birth weight was stronger in studies with median triclosan values ≥10 ng/mL compared to studies with median values < 10 ng/mL (β:-27 g; 95% CI:-61, 7; n = 4 vs. β:6g; 95% CI:-20, 31; n = 5). With a limited number of studies, we observed suggestive evidence that inverse associations were more apparent in studies with ≥ 2 prospective triclosan measures compared to those with one measure.

DISCUSSION

Available evidence, with "low" risk of bias, provides limited evidence that triclosan exposure and reduces infant birth weight. We observed stronger inverse associations between triclosan concentrations and birth weight in populations with higher triclosan exposure.

Urinary triclosan in south China adults and implications for human exposure

Triclosan (TCS) is widely applied in personal care products (PCPs) as an antimicrobial preservative. Due to its toxicity and potential risk to human health, TCS has attracted mounting concerns in recent years. However, biomonitoring of TCS in large human populations remains limited in China. In this study, 1163 adults in South China were recruited and urinary TCS concentrations were determined. TCS was detected in 99.5% of urine samples, indicating broad exposure in the study population. Urinary concentrations of TCS ranged from below the limit of detection (LOD) to 270 μg/L, with a median value of 3.67 μg/L. Urinary TCS concentrations from individuals were all lower than the Biomonitoring Equivalents reference dose, suggesting relatively low health risk in the participants. TCS concentrations did not differ significantly between sexes or education levels (p > 0.05). Nevertheless, marital status and age were found to be positively influence TCS levels (p < 0.001). After adjustment for body mass index (BMI), age was determined to be positively associated with TCS concentrations (p < 0.05), particularly in the age group from 31 to 51 years old. This study provides a baseline of urinary TCS exposure in South China general adult populations.

Association Between Gestational Exposure to Toxicants and Autistic Behaviors Using Bayesian Quantile Regression

Autism spectrum disorder, which is characterized by impaired social communication and stereotypic behaviors, affects 1%-2% of children. Although prenatal exposure to toxicants has been associated with autistic behaviors, most studies have been focused on shifts in mean behavior scores. We used Bayesian quantile regression to assess the associations between log2-transformed toxicant concentrations and autistic behaviors across the distribution of behaviors. We used data from the Maternal-Infant Research on Environmental Chemicals study, a pan-Canadian cohort (2008-2011). We measured metal, pesticide, polychlorinated biphenyl, phthalate, bisphenol-A, and triclosan concentrations in blood or urine samples collected during the first trimester of pregnancy. Using the Social Responsiveness Scale (SRS), in which higher scores denote more autistic-like behaviors, autistic behaviors were assessed in 478 children aged 3-4 years old. Lead, cadmium, and most phthalate metabolites were associated with mild increases in SRS scores at the 90th percentile of the SRS distribution. Manganese and some pesticides were associated with mild decreases in SRS scores at the 90th percentile of the SRS distribution. We identified several monotonic trends in which associations increased in magnitude from the bottom to the top of the SRS distribution. These results suggest that quantile regression can reveal nuanced relationships and, thus, should be more widely used by epidemiologists.

Critical windows of fluoride neurotoxicity in Canadian children

BACKGROUND

Fluoride has been associated with IQ deficits during early brain development, but the period in which children are most sensitive is unknown.

OBJECTIVE

We assessed effects of fluoride on IQ scores across prenatal and postnatal exposure windows.

METHODS

We used repeated exposures from 596 mother-child pairs in the Maternal-Infant Research on Environmental Chemicals pregnancy and birth cohort. Fluoride was measured in urine (mg/L) collected from women during pregnancy and in their children between 1.9 and 4.4 years; urinary fluoride was adjusted for specific gravity. We estimated infant fluoride exposure (mg/day) using water fluoride concentration and duration of formula-feeding over the first year of life. Intelligence was assessed at 3-4 years using the Wechsler Preschool and Primary Scale of Intelligence-III. We used generalized estimating equations to examine the associations between fluoride exposures and IQ, adjusting for covariates. We report results based on standardized exposures given their varying units of measurement.

RESULTS

The association between fluoride and performance IQ (PIQ) significantly differed across prenatal, infancy, and childhood exposure windows collapsing across child sex (p = .001). The strongest association between fluoride and PIQ was during the prenatal window, B = -2.36, 95% CI: -3.63, -1.08; the association was also significant during infancy, B = -2.11, 95% CI: -3.45, -0.76, but weaker in childhood, B = -1.51, 95% CI: -2.90, -0.12. Within sex, the association between fluoride and PIQ significantly differed across the three exposure windows (boys: p = .01; girls: p = .01); among boys, the strongest association was during the prenatal window, B = -3.01, 95% CI: -4.60, -1.42, whereas among girls, the strongest association was during infancy, B = -2.71, 95% CI: -4.59, -0.83. Full-scale IQ estimates were weaker than PIQ estimates for every window. Fluoride was not significantly associated with Verbal IQ across any exposure window.

CONCLUSION

Associations between fluoride exposure and PIQ differed based on timing of exposure. The prenatal window may be critical for boys, whereas infancy may be a critical window for girls.

Temporal Trends of Phenol, Paraben, and Triclocarban Exposure in California Pregnant Women during 2007-2014

Little is known about temporal trends of pregnant women's exposures to environmental phenols and parabens. We quantified four phenols [bisphenol A (BPA), bisphenol F, bisphenol S, and triclosan), four parabens [butyl paraben, ethyl paraben (ETPB), methyl paraben (MEPB), and propyl paraben (PRPB)], and triclocarban in 760 urine samples collected during 2007-2014 from 218 California pregnant women participating in a high-familial risk autism spectrum disorder cohort. We applied multiple regression to compute least square geometric means of urinary concentrations and computed average annual percent changes. We compared our urinary concentrations with those of other study populations to examine geographic variations in pregnant women's exposure to these target compounds. Urinary concentrations of BPA, MEPB, ETPB, and PRPB in this study population decreased over the study period [percent change per year (95% confidence interval): -5.7% (-8.2%, -3.2%); -13.0% (-18.1%, -7.7%); -5.5% (-11.0%, 0.3%); and -13.3% (-18.3%, -8.1%), respectively] and were consistently lower than those in pregnant women in other U.S. regions during the same study period. In recent years, certain phenols and parabens with known adverse health effects are being regulated or replaced with alternatives, which explains decreased body burdens observed in this study population. Either the national regulations or the advocacy campaigns in California may have influenced exposures or consumer product choices.

Effect of Maternal Triclosan Exposure on Neonatal Birth Weight and Children Triclosan Exposure on Children's BMI: A Meta-Analysis

Background: Triclosan (TCS) is an environmental chemical with endocrine disrupting effects and can enter the body through the skin or oral mucosa. Human data about the effect of TCS exposure during pregnancy on neonatal birth weight and TCS exposure during childhood on children's growth are scarce.

Objectives: To investigate the association between maternal urinary TCS level and neonatal birth weight, as well as children's urinary TCS level and children's body mass index (BMI).

Methods: A systematic literature search was conducted using PubMed, Cochrane Library, and Web of Science. Finally, seven epidemiological articles with 5,006 participants from September 25, 2014 to August 10, 2018 were included in the meta-analysis to identify the relationship between maternal exposure to TCS and neonatal birth weight. On the other hand, three epidemiological articles with 5,213 participants from July 22, 2014 to September 1, 2017 were included in another meta-analysis to identify the relationship between children's exposure to TCS and children's BMI. We used Stata 16.0 to test the heterogeneity among the studies and calculating the combined effect value 95% confidence interval (CI) of the selected corresponding models.

Results: TCS exposure during pregnancy was not significant associated with neonatal birth weight. The results of forest plots were as follows: ES (Estimate) = 0.41 (95% CI: −11.97–12.78). Children's urinary TCS level was also irrelevant associated with children's BMI: ES = 0.03 (95% CI: −0.54–0.60).

Conclusions: This meta-analysis demonstrated that there was no significant association between maternal TCS level and neonatal birth weight, also there has no relationship between children's urinary TCS level and children's BMI.

Topical Application of the Antimicrobial Agent Triclosan Induces NLRP3 Inflammasome Activation and Mitochondrial Dysfunction

5-Chloro-2-(2,4-dichlorophenoxy)phenol (triclosan) is an antimicrobial chemical widely used in consumer household and clinical healthcare products. Human and animal studies have associated triclosan exposure with allergic disease. Mechanistic studies have identified triclosan as a mitochondrial uncoupler; recent studies suggest that mitochondria play an important role in immune cell function and are involved in activation of the NLRP3 inflammasome. In this study, early immunological effects were evaluated via NLRP3 activation following dermal triclosan application in a BALB/c murine model. These investigations revealed rapid caspase-1 activation and mature IL-1β secretion in the skin and draining lymph nodes (dLNs) after 1.5% and 3% triclosan exposure. Correspondingly, pro-Il-1b and S100a8 gene expression increased along with extracellular ATP in the skin. Peak gene expression of chemokines associated with caspase-1 activation occurred after 2 days of exposure in both skin tissue and dLNs. Phenotypic analysis showed an increase in neutrophils and macrophages in the dLN and myeloid and inflammatory monocytes in the skin tissue. Triclosan also caused mitochondrial dysfunction shown through effects on mitochondrial reactive oxygen species, mass, mitochondrial membrane potential, and mitochondrial morphology. These results indicate that following triclosan exposure, activation of the NLRP3 inflammasome occurs in both the skin tissue and dLNs, providing a possible mechanism for triclosan's effects on allergic disease and further support a connection between mitochondrial involvements in immunological responses.

Chemical mixture exposures during pregnancy and cognitive abilities in school-aged children

INTRODUCTION

Gestational exposure to chemical mixtures, which is prevalent among pregnant women, may be associated with adverse childhood neurodevelopment. However, few studies have examined relations between gestational chemical mixture exposure and children's cognitive abilities.

METHODS

In a cohort of 253 pregnant women and their children from Cincinnati, OH (enrolled 2003-2006), we quantified biomarker concentrations of 43 metals, phthalates, phenols, polybrominated diphenyl ethers, organophosphate and organochlorine pesticides, polychlorinated biphenyls, perfluoroalkyl substances, and environmental tobacco smoke in blood or urine. Using k-means clustering and principal component (PC) analysis, we characterized chemical mixtures among pregnant women. We assessed children's cognitive abilities using the Wechsler Preschool and Primary Scale of Intelligence-III and Wechsler Intelligence Scale for Children-IV at ages 5 and 8 years, respectively. We estimated covariate-adjusted differences in children's cognitive ability scores ]=cross clusters, and with increasing PC scores and individual biomarker concentrations.

RESULTS

Geometric mean biomarker concentrations were generally highest, intermediate, and lowest among women in clusters 1, 2, and 3, respectively. Children born to women in clusters 1 and 2 had 5.1 (95% CI: 9.4,-0.8) and 2.0 (95% CI: 5.5, 1,4) lower performance IQ scores compared to children in cluster 3, respectively. PC scores and individual chemical biomarker concentrations were not associated with cognitive abilities.

CONCLUSIONS

In this cohort, combined prenatal exposure to phenols, certain phthalates, pesticides, and perfluoroalkyl substances was inversely associated with children's cognition, but some individual chemical biomarker concentrations were not. Additional studies should determine if the aggregate impact of these chemicals on cognition is different from their individual effects.

Integrated Proteomics and Metabolomics Assessment Indicated Metabolic Alterations in Hypothalamus of Mice Exposed to Triclosan

Triclosan (TCS) is a ubiquitous antimicrobial used in many daily consumer products. It has been reported to induce endocrine disrupting effects at low doses in mammals, disturbing sex hormone function and thyroid function. The hypothalamus plays a crucial role in the maintenance of neuroendocrine function and energy homeostasis. We speculated that the adverse effects of TCS might be related to the disturbance of metabolic processes in hypothalamus. The present study aimed at investigating the effects of TCS exposure on the protein and metabolite profiles in hypothalamus of mice. Male C57BL/6 mice were orally exposed to TCS at the dosage of 10 mg/kg/d for 13 weeks. The hypothalamus was isolated and processed for mass spectrometry (MS)-based proteomics and metabolomics analyses. The results showed that a 10.6% decrease (P = 0.066) in body weight gain was observed in the TCS exposure group compared with vehicle control group. Differential analysis defined 52 proteins and 57 metabolites that delineated TCS exposed mice from vehicle controls. Among the differential features, multiple proteins and metabolites were found to play vital roles in neuronal signaling and function. Bioinformatics analysis revealed that these differentially expressed proteins and metabolites were involved in four major biological processes, including glucose metabolism, purine metabolism, neurotransmitter release, and neural plasticity, suggesting the disturbance of homeostasis in energy metabolism, mitochondria function, neurotransmitter system, and neuronal function. Our results may provide insights into the neurotoxicity of TCS and extend our understanding of the biological effects induced by TCS exposure.

Gestational and childhood exposure to per- and polyfluoroalkyl substances and cardiometabolic risk at age 12 years

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) may adversely influence cardiometabolic risk. However, few studies have examined if the timing of early life PFAS exposure modifies their relation to cardiometabolic risk. We examined the influence of gestational and childhood PFAS exposure on adolescents' cardiometabolic risk.

METHODS

We quantified concentrations of four PFAS (perfluorooctanoate [PFOA], perfluorooctane sulfonate [PFOS], perfluorononanoate [PFNA], and perfluorohexane sulfonate [PFHxS]) in sera collected during pregnancy, at birth, and at ages 3, 8, and 12 years from 221 mother-child pairs in the HOME Study (enrolled 2003-06, Cincinnati, Ohio). We measured cardiometabolic risk factors using physical examinations, fasting serum biomarkers, and dual-energy X-ray absorptiometry scans at age 12 years. Cardiometabolic risk summary scores were calculated by summing age- and sex-standardized z-scores for individual cardiometabolic risk factors. We used multiple informant models to estimate covariate-adjusted associations of serum PFAS concentrations (log2-transformed) at each visit with cardiometabolic risk scores and their individual components, and tested for differences in associations across visits.

RESULTS

The associations of serum PFOA concentrations with cardiometabolic risk scores differed across visits (P for heterogeneity = 0.03). Gestational and cord serum PFOA concentrations were positively associated with cardiometabolic risk scores (βs and 95% confidence intervals [95% CIs]: gestational 0.8 [0.0, 1.6]; cord 0.9 [-0.1, 1.9] per interquartile range increase). These positive associations were primarily driven by homeostatic model assessment for insulin resistance index (β = 0.3 [0.1, 0.5]) and adiponectin to leptin ratio (β = -0.5 [-1.0, 0.0]). Other individual cardiometabolic risk factors associated with gestational PFOA included insulin and waist circumference. Gestational and cord PFHxS were also associated with higher cardiometabolic risk scores (βs: gestational 0.9 [0.2, 1.6]; cord 0.9 [0.1, 1.7]).

CONCLUSION

In this cohort of children with higher gestational PFOA exposure, fetal exposure to PFOA and PFHxS was associated with unfavorable cardiometabolic risk in adolescence.

Comparison of strategies to efficiently combine repeated urine samples in biomarker-based studies

BACKGROUND

In biomarker-based studies, collecting repeated biospecimens per participant can decrease measurement error, particularly for biomarkers displaying high within-subject variability. Guidelines to combine such repeated biospecimens do not exist.

AIMS

To compare the efficiency of several designs relying on repeated biospecimens to estimate exposure over 7 days.

METHODS

We quantified triclosan and bisphenol A (BPA) in all urine voids (N = 427) collected over seven days from eight individuals. We estimated the volume-weighted concentrations for all urine samples collected during a week and compared these gold standards with the concentrations obtained for equal-volume pools (standardized or not for urine dilution), unequal-volume pools (based on sample volume or creatinine concentration), and for the mean of the creatinine-standardized concentrations measured in each spot sample.

RESULTS

For both chemicals, correlations with gold standards were similar for equal- and unequal-volume pooling designs. Only for BPA, correlation coefficients were markedly lower after standardization for specific gravity or creatinine of concentrations estimated in equal-volume pools. Averaging BPA creatinine-standardized concentrations measured in each spot sample led also to lower correlations with gold standards compared to those obtained for unstandardized pooling designs.

CONCLUSION

For BPA and triclosan, considering individual urine sample volume or creatinine concentrations when pooling is unnecessary because equal-volume pool adequately estimates concentrations in gold standards. Standardization for specific gravity or creatinine of the concentrations assessed in equal-volume pool as well as averaging creatinine-standardized concentrations measured in each individual spot sample are not suitable for BPA. These results provide a practical framework on how to combine repeated biospecimens in epidemiological studies.

Maternal and childhood urinary phenol concentrations, neonatal thyroid function, and behavioral problems at 10 years of age: The SMBCS study

BACKGROUND

Environmental phenols, bisphenol A (BPA), triclosan (TCS), and benzophenone-3 (BP-3), are known as emerging endocrine-disrupting chemicals; however, their impacts on thyroid hormones and children's neurobehaviors are still unclear.

OBJECTIVES

We aimed to examine the associations of prenatal and childhood exposure to phenols with neonatal thyroid function and childhood behavioral problems aged 10 years.

METHODS

A total of 386 mother-singleton pairs were included from Sheyang Mini Birth Cohort Study (SMBCS), a longitudinal birth cohort in China. We quantified urinary BPA, TCS and BP-3 concentrations in maternal and 10-year-old children's urine samples using gas chromatography tandem mass spectrometry and thyroid function parameters in cord serum samples. Caregivers completed the Strength and Difficulties Questionnaire (SDQ) for their children at 10 years of age. Multivariable linear regression models and logistic regression models were applied to estimate associations of urinary phenol concentrations with thyroid hormones and risks of children's behavioral problems, respectively.

RESULTS

The median values of urinary BPA, TCS and BP-3 concentrations for pregnant women were 1.75 μg/L, 0.54 μg/L and 0.37 μg/L, while 1.29 μg/L, 6.64 μg/L and 1.39 μg/L for children, respectively. Maternal urinary BPA concentrations were in associations with 1.00% [95% confidence interval (CI): 0.20%, 1.92%] increases in cord serum FT4 concentrations and significantly associated with increased risks of total difficulties [odds ratio (OR): 1.45, 95% CI: 1.07, 1.97], while maternal urinary levels of BP-3 were significantly related to poorer prosocial behaviors (OR: 1.58, 95% CI: 1.04, 2.39) of children at 10 years of age. In sex-stratified analyses, maternal urinary BPA concentrations were related to increased total difficulty subscales only in boys.

CONCLUSIONS

The findings indicated that higher prenatal urinary BPA concentrations were associated with increased risks of total difficulties, especially in boys and maternal urinary BP-3 concentrations were related to poorer prosocial behaviors at 10 years.

Gestational and childhood exposure to phthalates and child behavior

BACKGROUND

Early-life phthalate exposures may adversely influence neurodevelopment by disrupting thyroid hormone homeostasis, altering brain lipid metabolism, or reducing gonadal hormone concentrations. Previous literature examining gestational phthalate exposure and child behavior were inconclusive and few prospective studies have examined childhood phthalate exposure, particularly phthalate mixtures. We investigated whether gestational and childhood phthalate exposures were associated with child behavior.

METHODS

We used data from 314 mother-child pairs in the HOME Study, a longitudinal pregnancy and birth cohort that enrolled pregnant women from Cincinnati, Ohio. We quantified urinary concentrations of 11 phthalate metabolites in samples collected twice during gestation from women and six times from their children when they were ages 1, 2, 3, 4, 5, and 8 years. We assessed children's behavior at ages 2, 3, 4, 5, and 8 years using the Behavioral Assessment System for Children-2. Using linear mixed models, we estimated covariate-adjusted associations of measurement-error-corrected gestational and childhood phthalate metabolite concentrations (per interquartile range increase) with repeated child behavior assessments. We used Weighted Quantile Sum (WQS) regression to estimate the association of phthalate mixtures with child behavior.

RESULTS

Gestational mono(3-carboxypropyl) phthalate (MCPP) concentrations were associated with more problem behaviors (internalizing: β = 0.9, 95% confidence interval [CI] = -0.1, 1.9; externalizing: β = 1.0, 95%CI = -0.1, 2.0; behavioral symptoms index [BSI]: β = 1.1, 95%CI = 0.1, 2.1). Higher childhood monobenzyl phthalate (MBzP) (β = 1.4; 95%CI = 0.0, 2.7), monocarboxynonyl phthalate (MCNP) (β = 3.2; 95%CI = 1.6, 4.8), monocarboxyoctyl phthalate (MCOP) (β = 0.9; 95%CI = 0.0, 1.7), MCPP (β = 1.8; 95%CI = 0.2, 3.5), and monoethyl phthalate (MEP) (β = 1.6; 95%CI = 0.1, 3.1) concentrations were associated with higher BSI composite scores. Consistent with this, the weighted childhood phthalate index was associated with more problem behaviors (internalizing: β = 1.5, 95%CI = -0.2, 3.1; externalizing: β = 1.7, 95%CI = 0.1, 3.5; BSI: β = 1.7, 95%CI = 0.2, 3.2); MBzP, MCNP, and MEP largely contributed to these associations.

CONCLUSION

Our findings suggest that childhood exposure to phthalate mixtures may be associated with children's problem behaviors.

Triclosan disrupts immune cell function by depressing Ca2+ influx following acidification of the cytoplasm

Triclosan (TCS) is an antimicrobial agent that was effectively banned by the FDA from hand soaps in 2016, hospital soaps in 2017, and hand sanitizers in 2019; however, TCS can still be found in a few products. At consumer-relevant, non-cytotoxic doses, TCS inhibits the functions of both mitochondria and mast cells, a ubiquitous cell type. Via the store-operated Ca2+ entry mechanism utilized by many immune cells, mast cells undergo antigen-stimulated Ca2+ influx into the cytosol, for proper function. Previous work showed that TCS inhibits Ca2+ dynamics in mast cells, and here we show that TCS also inhibits Ca2+ mobilization in human Jurkat T cells. However, the biochemical mechanism behind the Ca2+ dampening has yet to be elucidated. Three-dimensional super-resolution microscopy reveals that TCS induces mitochondrial swelling, in line with and extending the previous finding of TCS inhibition of mitochondrial membrane potential via its proton ionophoric activity. Inhibition of plasma membrane potential (PMP) by the canonical depolarizer gramicidin can inhibit mast cell function. However, use of the genetically encoded voltage indicators (GEVIs) ArcLight (pH-sensitive) and ASAP2 (pH-insensitive), indicates that TCS does not disrupt PMP. In conjunction with data from a plasma membrane-localized, pH-sensitive reporter, these results indicate that TCS, instead, induces cytosolic acidification in mast cells and T cells. Acidification of the cytosol likely inhibits Ca2+ influx by uncoupling the STIM1/ORAI1 interaction that is required for opening of plasma membrane Ca2+ channels. These results provide a mechanistic explanation of TCS disruption of Ca2+ influx and, thus, of immune cell function.

Gestational and childhood urinary triclosan concentrations and academic achievement among 8-year-old children

BACKGROUND

Early life exposure to triclosan, an antimicrobial chemical and suspected endocrine disruptor, may adversely affect neurodevelopment. No studies have examined gestational and early childhood exposure to triclosan and children's academic achievement.

METHODS

Using data from 193 mother-child pairs from the HOME Study, we quantified triclosan in maternal and child urine samples up to nine times between the second trimester of gestation (16-weeks) and age 8 years. At age 8 years, we administered the reading and math components of the Wide Range Achievement Test-4 (WRAT-4) to children. Using multiple informants models, we estimated covariate-adjusted associations of triclosan concentrations during each time period with WRAT-4 scores. We also tested whether associations differed by exposure period and child sex.

RESULTS

There was evidence that timing of exposure modified the associations between triclosan and reading composite scores (triclosan-exposure period interaction p-value = 0.20), but not math scores (interaction p-value = 0.72). Each 10-fold increase in triclosan concentrations at delivery was associated with lower reading composite scores (β:-2.6; 95 % CI:-5.0, -0.1). Additionally, we observed weaker and less precise inverse association of math scores with triclosan concentrations at delivery (β:-1.9; 95 % CI:-4.6, 0.8) and at age 1 year (β:-2.0; 95 % CI:-6.0, 2.1). There was not strong evidence that child sex modified the pattern of associations between repeated triclosan measures and WRAT-4 reading composite or math scores (sex-triclosan-exposure period interaction p-values>0.20).

CONCLUSION

Urinary triclosan concentrations at delivery and at age 1 year, but not other times during gestation or childhood, were associated with lower reading composite and to a lesser extent math test scores at age 8 years in this cohort of U.S. children.

Lipid metabolism disorders contribute to hepatotoxicity of triclosan in mice

Previous in vivo exposure studies focused mainly on nuclear receptors involved in hepatotoxicity of triclosan (TCS). As liver plays a vital role in metabolic processes, dysregulations in lipid metabolism have been identified as potential drivers of pathogenesis. Investigation of changes in lipid metabolism might widen our understanding of toxicological effects as well as the underlying mechanism occurring in the liver. In this study, we comprehensively assessed the effect of TCS exposure on hepatic lipid metabolism in mice. Our results showed that TCS induced significant changes in hepatic free fatty acid pool by upregulation of fatty acid uptake and de novo fatty acid synthesis. Besides, hepatic levels of lipids, including acyl carnitine (AcCa), ceramide (Cer), triacylglycerols (TG), phosphatidylcholine (PC), lysophosphatidylcholine (LPC), phosphatidylethanolamine (PE) were also increased, together with upreguation of genes associated to TG synthesis, fatty acid oxidation and inflammation in TCS exposure group. These changes in lipid homeostasis could contribute to membrane instability, lipid accumulation, oxidative stress and inflammation. Our results suggested that TCS exposure could induce hepatic lipid metabolism disorders in mice, which would further contribute to the liver damage effects of TCS.

Early prenatal exposure to suspected endocrine disruptor mixtures is associated with lower IQ at age seven

BACKGROUND

Endocrine disrupting chemicals (EDCs) are xenobiotics with the ability to interfere with hormone action, even at low levels. Prior environmental epidemiology studies link numerous suspected EDCs, including phthalates and bisphenol A (BPA), to adverse neurodevelopmental outcomes. However, results for some chemicals were inconsistent and most assessed one chemical at a time.

OBJECTIVES

To evaluate the overall impact of prenatal exposure to an EDC mixture on neurodevelopment in school-aged children, and identify chemicals of concern while accounting for co-exposures.

METHODS

Among 718 mother-child pairs from the Swedish Environmental Longitudinal, Mother and child, Asthma and allergy study (SELMA) study, we used Weighted Quantile Sum (WQS) regression to assess the association between 26 EDCs measured in 1st trimester urine or blood, with Wechsler Intelligence Scale for Children (IV) Intelligence Quotient (IQ) scores at age 7 years. Models were adjusted for child sex, gestational age, mother's education, mother's IQ (RAVEN), weight, and smoking status. To evaluate generalizability, we conducted repeated holdout validation, a machine learning technique.

RESULTS

Using repeated holdout validation, IQ scores were 1.9-points (CI = -3.6, -0.2) lower among boys for an inter-quartile-range (IQR) change in the WQS index. BPF made the largest contribution to the index with a weight of 14%. Other chemicals of concern and their weights included PBA (9%), TCP (9%), MEP (6%), MBzP (4%), PFOA (6%), PFOS (5%), PFHxS (4%), Triclosan (5%), and BPA (4%). While we did observe an inverse association between EDCs and IQ among all children when training and testing the WQS index estimate on the full dataset, these results were not robust to repeated holdout validation.

CONCLUSION

Among boys, early prenatal exposure to EDCs was associated with lower intellectual functioning at age 7. We identified bisphenol F as the primary chemical of concern, suggesting that the BPA replacement compound may not be any safer for children. Future studies are needed to confirm the potential neurotoxicity of replacement analogues.

Triclosan: antimicrobial mechanisms, antibiotics interactions, clinical applications, and human health

The large-scale applications of Triclosan in industrial and household products have created many health and environmental concerns. Despite the fears of its drug-resistance and other issues, Triclosan is still an effective drug against many infectious organisms. Knowing the cross-interactions of Triclosan with different antibiotics, bacteria, and humans can provide much-needed information for the risk assessment of this drug. We review the current understanding of the antimicrobial mechanisms of Triclosan, how microbes become resistant to Triclosan, and the synergistic and antagonistic effects of Triclosan with different antibiotics. Current literature on the clinical applications of Triclosan and its effect on fetus/child development are also summarized.

Prenatal phenol and paraben exposures in relation to child neurodevelopment including autism spectrum disorders in the MARBLES study

BACKGROUND

Environmental phenols and parabens are endocrine disrupting chemicals (EDCs) with the potential to affect child neurodevelopment including autism spectrum disorders (ASD). Our aim was to assess whether exposure to environmental phenols and parabens during pregnancy was associated with an increased risk of clinical ASD or other nontypical development (non-TD).

METHODS

This study included mother-child pairs (N = 207) from the Markers of Autism Risks in Babies - Learning Early Signs (MARBLES) Cohort Study with urinary phenol and paraben metabolites analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) from repeated pregnancy urine samples. Because family recurrence risks in siblings are about 20%, MARBLES enrolls pregnant women who already had a child with ASD. Children were clinically assessed at 3 years of age and classified into 3 outcome categories: ASD, non-TD, or typically developing (TD). Single analyte analyses were conducted with trinomial logistic regression and weighted quantile sum (WQS) regression was used to test for mixture effects.

RESULTS

Regression models were adjusted for pre-pregnancy body mass index, prenatal vitamin use (yes/no), homeowner status (yes/no), birth year, and child's sex. In single chemical analyses phenol exposures were not significantly associated with child's diagnosis. Mixture analyses using trinomial WQS regression showed a significantly increased risk of non-TD compared to TD (OR = 1.58, 95% CI: 1.04, 2.04) with overall greater prenatal phenol and paraben metabolites mixture. Results for ASD also showed an increased risk, but it was not significant.

DISCUSSION

This is the first study to provide evidence that pregnancy environmental phenol exposures may increase the risk for non-TD in a high-risk population.

Antimicrobial agent triclosan suppresses mast cell signaling via phospholipase D inhibition

Humans are exposed to the antimicrobial agent triclosan (TCS) through use of TCS-containing products. Exposed tissues contain mast cells, which are involved in numerous biological functions and diseases by secreting various chemical mediators through a process termed degranulation. We previously demonstrated that TCS inhibits both Ca²⁺ influx into antigen-stimulated mast cells and subsequent degranulation. To determine the mechanism linking the TCS cytosolic Ca²⁺ depression to inhibited degranulation, we investigated the effects of TCS on crucial signaling enzymes activated downstream of the Ca²⁺ rise: protein kinase C (PKC; activated by Ca²⁺ and reactive oxygen species [ROS]) and phospholipase D (PLD). We found that TCS strongly inhibits PLD activity within 15 minutes post-antigen, a key mechanism of TCS mast cell inhibition. In addition, experiments using fluorescent constructs and confocal microscopy indicate that TCS delays antigen-induced translocations of PKCβII, PKCδ and PKC substrate myristoylated alanine-rich C-kinase. Surprisingly, TCS does not inhibit PKC activity or overall ability to translocate, and TCS actually increases PKC activity by 45 minutes post-antigen; these results are explained by the timing of both TCS inhibition of cytosolic Ca²⁺ (~15+ minutes post-antigen) and TCS stimulation of ROS (~45 minutes post-antigen). These findings demonstrate that it is incorrect to assume that all Ca²⁺ -dependent processes will be synchronously inhibited when cytosolic Ca²⁺ is inhibited by a toxicant or drug. The results offer molecular predictions of the effects of TCS on other mammalian cell types, which share these crucial signal transduction elements and provide biochemical information that may underlie recent epidemiological findings implicating TCS in human health problems.

Triclosan induces PC12 cells injury is accompanied by inhibition of AKT/mTOR and activation of p38 pathway

Triclosan (TCS) has been widely used as a disinfectant and antiseptic in multiple consumer and healthcare products due to its clinical effectiveness against various bacteria, fungi and protozoa. Recently, several studies have reported the adverse effects of TCS on various nerve cells, arousing concerns about its potential neurotoxicity. The present study aimed to investigate the neurotoxicity of TCS in rat pheochromocytoma PC12 cells. After differentiation, the stabilized PC12 cells were treated with 1, 10, 50 μM TCS for 12 h. At the end of the treatment, the generation of reactive oxygen species (ROS), protein expression of apoptotic-related genes, AMPK-AKT/mTOR, as well as p38 in PC12 cells were determined. The concentrations were chosen based on the results of cell viability and lactic dehydrogenase (LDH) assays in response to TCS treatment (ranging from 0.001 to 100 μM) for varied time periods. The results showed that TCS is cytotoxic to PC12 cells, causing decreased cell viability accompanied by increased LDH release. TCS treatment at 10 and 50 μM for 12 h increased the mRNA and protein expression of the pro-apoptotic gene Bax, while Bcl-2 levels remained unchanged. Moreover, an increase in the generation of reactive oxygen species (ROS) was found in TCS-treated PC12 cells at the concentrations of 1 and 10 μM. Pretreatment with 100 μM N-acetyl cysteine (NAC- ROS scavenger) for 1 h normalized the ROS generations in TCS-treated PC12 cells. Additionally, the suppression of the phosphorylation of Akt and mTOR was observed in TCS-treated PC12 cells at 10 and 50 μM for 12 h, concomitant with the activation of p38 MAPK pathway at 50 μM TCS. However, there were no effects of TCS on the phosphorylation of AMPK in these cells. Taken together, these results suggest that TCS may cause adverse effects and oxidative stress in PC12 cells accompanied by inhibition of Akt/mTOR and activation of p38.

Early-life triclosan exposure and parent-reported behavior problems in 8-year-old children

BACKGROUND

Triclosan exposure may decrease circulating thyroxine levels or cause neuron apoptosis, which in turn may adversely affect neurodevelopment. However, few studies have examined the association of early life triclosan exposure with child behavior.

OBJECTIVE

To quantify the association between early-life triclosan exposure and child behavior at age 8-years in 202 mother-child pairs from the HOME study (Cincinnati, OH; enrolled: 2003-2006).

METHODS

We quantified urinary triclosan concentrations up to 3 times in mothers (16-weeks, 26-weeks, and delivery) and up to 6 times in children (1, 2, 3, 4, 5, and 8 years). Parents rated children's problem behaviors at age 8-years using the Behavioral Assessment System for Children-2 (BASC-2). Adjusting for covariates and accounting for exposure measurement error, we estimated changes in behavior problem scores per 10-fold increase in mean gestational and childhood triclosan concentrations. In addition, we estimated sex-specific associations.

RESULTS

Child sex modified the association of gestational and childhood triclosan with several BASC-2 scales (sex × triclosan p-values < 0.2). In boys, increasing gestational triclosan was associated with higher behavioral symptom index (β: 4.5; 95% CI: 1.0, 8.1), externalizing problems (β: 5.0; 95% CI: 1.2, 9.0), attention problem (β: 6.6; 95% CI: 2.4, 11), hyperactivity (β: 6.4; 95% CI: 2.1, 11), and somatization (β: 3.8; 95% CI: 0.3, 7.3) scores. In contrast, triclosan-BASC-2 associations in girls were generally null and not statistically significant. We observed similar patterns of associations between childhood triclosan and these same behavioral scores; however, their magnitude decreased substantially after adjusting for gestational triclosan and associations were not statistically significant.

CONCLUSION

In this cohort, increasing gestational and childhood urinary triclosan concentrations were associated with higher behavior problem scores in 8-year old boys, but not girls.

Use of antibacterial toothpaste is associated with higher urinary triclosan concentrations in Asian immigrant women living in Vancouver, Canada

BACKGROUND

Triclosan is an antibacterial added to consumer products including toothpastes, cosmetics, and plastic cutting boards. Known to disrupt reproductive and hormonal functioning in animals, epidemiological studies indicate that exposure to triclosan may have similar effects on human health.

METHODS

100 women aged 19 to 45 years born in India or China, Hong Kong, and Taiwan new to the Vancouver (Canada) area were recruited in 2015-2016 by word of mouth, public advertisements, and contacts in health and cultural organizations. Participants completed an interview which queried potential sources of triclosan exposure at home and at work and their urine was tested for triclosan by GC-MS. Determinants of urinary triclosan were assessed by Wilcoxon signed-rank test.

RESULTS

Triclosan was detected in 62% of urine samples, with an overall GM of 14.5 μg/L (95% CI: 9.7-21.7 μg/L; range: <LOD to 1900 μg/L). Colgate Total® toothpaste users had higher urinary triclosan concentrations (median = 34.0 μg/L) than non-users (median = 2.5 μg/L, ρ < 0.001), a result which was unaffected by adjustment for age, income, BMI, and country of birth. South Asian born women had elevated urinary triclosan compared to East Asian born women.

CONCLUSION

Triclosan exposure via a specific antibacterial toothpaste brand was identified in reproductive age newcomer women in Canada. Health education around brushing teeth well while using lower toothpaste volumes or choosing triclosan-free toothpaste would reduce triclosan exposure.

Statistical Approaches for Investigating Periods of Susceptibility in Children's Environmental Health Research

PURPOSE OF REVIEW

Children's environmental health researchers are increasingly interested in identifying time intervals during which individuals are most susceptible to adverse impacts of environmental exposures. We review recent advances in methods for assessing susceptible periods.

RECENT FINDINGS

We identified three general classes of modeling approaches aimed at identifying susceptible periods in children's environmental health research: multiple informant models, distributed lag models, and Bayesian approaches. Benefits over traditional regression modeling include the ability to formally test period effect differences, to incorporate highly time-resolved exposure data, or to address correlation among exposure periods or exposure mixtures. Several statistical approaches exist for investigating periods of susceptibility. Assessment of susceptible periods would be advanced by additional basic biological research, further development of statistical methods to assess susceptibility to complex exposure mixtures, validation studies evaluating model assumptions, replication studies in different populations, and consideration of susceptible periods from before conception to disease onset.

Identifying periods of susceptibility to the impact of phthalates on children's cognitive abilities

BACKGROUND

Early-life phthalate exposures may adversely affect children's neurodevelopment by disrupting thyroid function, reducing gonadal hormone levels, or altering fatty acid concentrations in the brain. This study aimed to identify periods of heightened susceptibility during gestation, infancy, and childhood to the impact of phthalates on children's cognitive abilities.

METHODS

We used data from 253 mother-child pairs in the Health Outcomes and Measures of the Environment (HOME) Study (Cincinnati, Ohio), a longitudinal pregnancy and birth cohort. We quantified urinary concentrations of 11 phthalate metabolites in samples collected twice during gestation and 6 times during study visits when children were aged 1-8 years using a modified method of on-line solid phase extraction coupled with isotope dilution-high performance liquid chromatography-tandem mass spectrometry. We assessed children's intelligence (IQ) at ages 5 and 8 years using the Wechsler Preschool and Primary Scale of Intelligence-III and Wechsler Intelligence Scale for Children-IV, respectively. We estimated covariate-adjusted associations between a 1-standard deviation increase in log10-transformed urinary phthalate metabolite concentrations at each visit and children's IQ, adjusting for demographic, perinatal, and child factors; we tested for differences in these associations across visits using multiple informant models.

RESULTS

Associations between some phthalate metabolites and IQ varied by visit (phthalate x visit interaction p-values<0.20). The sum of di(2-ethylhexyl) phthalate metabolites (ΣDEHP), mono(3-carboxypropyl) phthalate, and monoethyl phthalate at age 3 years, and monobenzyl phthalate at 16 weeks gestation and child ages 3, 5, and 8 years were inversely associated with children's full-scale IQ. For example, each 1-standard deviation increase in ΣDEHP at age 3 was associated with a 1.9-point decrease in full-scale IQ (95% confidence interval: -3.7, -0.2). Mono-n-butyl phthalate and mono-isobutyl phthalate at age 4 years were positively associated with children's full-scale IQ.

CONCLUSION

Urinary concentrations of several phthalate metabolites at age 3 years, compared to other time periods, were more strongly associated with decreased cognitive abilities in these children.

Prenatal exposure to benzophenones, parabens and triclosan and neurocognitive development at 2 years

BACKGROUND

Benzophenones (BPs), parabens, and triclosan (TCS) are widely used in personal care products and may be neurotoxic to children, but limited studies have estimated the associations between exposure to these potential endocrine disrupting chemicals during pregnancy and child neurocognitive development.

OBJECTIVE

Our aim was to evaluate the relationships of prenatal exposure to BPs, parabens and TCS with child neurocognitive development at age 2.

METHODS

From 2014 to 2015, 478 mother-child pairs from a longitudinal prenatal cohort in China were included in present study. We quantified BPs, parabens and TCS in three spot urine samples during pregnancy (in the first, second, and third trimester). The Bayley Scales of Infant Development (BSID) test to children was performed at 2 years. Multivariate linear regression models and generalized estimating equations were used to examine changes in mental developmental index (MDI) and psychomotor development index (PDI) per 2-fold increase in averaged and trimester-specific maternal urinary phenols, respectively.

RESULTS

In the adjusted models, each 2-fold increase in average prenatal paraben concentration was associated with lower MDI scores among girls [-1.08 (95% CI: -2.10, -0.06) and - 1.51 (95% CI: -2.69, -0.32) for methyl paraben (Mep) and Σparabens, respectively], but the association was not statistically significant among boys [-0.24 (95% CI: -1.46, 0.99), P_sex-int = 0.37 and 0.18 (95% CI: -1.28, 1.64), P_sex-int = 0.10 for Mep and Σparabens, respectively]. Increasing urinary 4-hydroxybenzophenone (4-OH-BP) concentration was associated with lower PDI scores among boys [-2.96 (95% CI: -4.48, -1.45)], not girls [-0.07 (95% CI: -1.57, 1.43)] and the association was significantly different in boys and girls (P_sex-int = 0.01). No significant associations were observed between the average prenatal TCS exposure and BSID results. In trimester-specific analyses, increasing parabens was associated with lower girls' MDI only in the second trimester, while increasing 4-OH-BP was associated with lower boys' PDI in each trimester.

CONCLUSION

Our results suggest that prenatal exposure to BPs and parabens may be associated with impairment in child cognitive abilities at 2 years. Further human and animal studies are needed to verify our results and elucidate the biological mechanisms involved in these associations.

A repeated measures study of phenol, paraben and Triclocarban urinary biomarkers and circulating maternal hormones during gestation in the Puerto Rico PROTECT cohort

INTRODUCTION

Prenatal exposure to some phenols and parabens has been associated with adverse birth outcomes. Hormones may play an intermediate role between phenols and adverse outcomes. We examined the associations of phenol and paraben exposures with maternal reproductive and thyroid hormones in 602 pregnant women in Puerto Rico. Urinary triclocarban, phenol and paraben biomarkers, and serum hormones (estriol, progesterone, testosterone, sex-hormone-binding globulin (SHBG), corticotropin-releasing hormone (CRH), total triiodothyronine (T3), total thyroxine (T4), free thyroxine (FT4) and thyroid-stimulating hormone (TSH)) were measured at two visits during pregnancy.

METHODS

Linear mixed models with a random intercept were constructed to examine the associations between hormones and urinary biomarkers. Results were additionally stratified by study visit. Results were transformed to hormone percent changes for an inter-quartile-range difference in exposure biomarker concentrations (%Δ).

RESULTS

Bisphenol-S was associated with a decrease in CRH [(%Δ -11.35; 95% CI: -18.71, - 3.33), and bisphenol-F was associated with an increase in FT4 (%Δ: 2.76; 95% CI: 0.29, 5.22). Butyl-, methyl- and propylparaben were associated with decreases in SHBG [(%Δ: -5.27; 95% CI: -9.4, - 1.14); (%Δ: -3.53; 95% CI: -7.37, 0.31); (%Δ: -3.74; 95% CI: -7.76, 0.27)]. Triclocarban was positively associated with T3 (%Δ: 4.08; 95% CI: 1.18, 6.98) and T3/T4 ratio (%Δ: 4.67; 95% CI: -1.37, 6.65), and suggestively negatively associated with TSH (%Δ: -10.12; 95% CI: -19.47, 0.32). There was evidence of susceptible windows of vulnerability for some associations. At 24-28 weeks gestation, there was a positive association between 2,4-dichlorophenol and CRH (%Δ: 9.66; 95% CI: 0.67, 19.45) and between triclosan and estriol (%Δ: 13.17; 95% CI: 2.34, 25.2); and a negative association between triclocarban and SHBG (%Δ: -9.71; 95% CI:-19.1, - 0.27) and between bisphenol A and testosterone (%Δ: -17.37; 95% CI: -26.7, - 6.87).

CONCLUSION

Phenols and parabens are associated with hormone levels during pregnancy. Further studies are required to substantiate these findings.

Neurotoxicological effects induced by up-regulation of miR-137 following triclosan exposure to zebrafish (Danio rerio)

Triclosan (TCS) is a prevalent anthropogenic contaminant in aquatic environments and its chronic exposure can lead to a series of neurotoxic effects in zebrafish. Both qRT-PCR and W-ISH identified that TCS exposure resulted in significant up-regulation of miR-137, but downregulation of its regulatory genes (bcl11aa, MAPK6 and Runx1). These target genes are mainly associated with neurodevelopment and the MAPK signaling pathway, and showed especially high expression in the brain. After overexpression or knockdown treatments by manual intervention of miR-137, a series of abnormalities were induced, such as ventricular abnormality, bent spine, yolk cyst, closure of swim sac and venous sinus hemorrhage. The most sensitive larval toxicological endpoint from intervened miR-137 expression was impairment of the central nervous system (CNS), ventricular abnormalities and notochord curvature. Microinjection of microRNA mimics or inhibitors of miR-137 both caused zebrafish malformations. The posterior lateral line neuromasts became obscured and decreased in number in intervened miR-137 groups and TCS-exposure groups. Up-regulation of miR-137 led to more severe neurotoxic effects than its down-regulation. Behavioral observations demonstrated that both TCS exposure and miR-137 over-expression led to inhibited hearing or vision sensitivity. HE staining indicated that hearing and vision abnormalities induced by long-term TCS exposure originated from CNS injury, such as reduced glial cells and loose and hollow fiber structures. The findings of this study enhance our mechanistic understanding of neurotoxicity in aquatic animals in response to TCS exposure. These observations provide theoretical guidance for development of early intervention treatments for nervous system diseases.

Cross-sectional associations between urinary triclosan and serum thyroid function biomarker concentrations in women

INTRODUCTION

Exposure to the antimicrobial agent triclosan is ubiquitous. Research in animals shows that triclosan can cause decreases in thyroxine concentrations. However, the potential effects of triclosan on thyroid function in humans are unclear.

OBJECTIVE

To estimate the association between urinary triclosan concentrations and serum thyroid function biomarkers in women seeking assisted reproduction treatment in the Environment and Reproductive Health (EARTH) Study.

METHODS

We conducted a cross-sectional study of 317 women enrolled in the EARTH Study, a prospective preconception cohort that recruits Boston area couples. Using samples collected at study entry, we quantified urinary triclosan and serum thyroid function biomarker concentrations, specifically free and total thyroxine and triiodothyronine, thyroid-stimulating hormone (TSH), and thyroid antibodies. We estimated covariate-adjusted differences in thyroid function biomarkers per 10-fold increase in triclosan using linear regression models. We examined effect modification by body mass index (BMI) and infertility diagnosis.

RESULTS

The median urinary triclosan concentration was 7.8 μg/L (IQR: 3.0-59 μg/L). Each 10-fold increase in triclosan was inversely associated with free triidothyronine (T₃) (β: -0.06 pg/mL; 95% CI: -0.1, -0.01), thyroperoxidase antibody (TPOAb) (-10%; 95% CI: -19, -0.4), and thyroglobulin antibody (TgAb) (-12%; 95% CI: -23,0.9) concentrations. BMI and infertility diagnosis modified the association of triclosan with free T₃ and TPOAb, respectively.

CONCLUSION

Urinary triclosan concentrations were inversely associated with specific serum thyroid function biomarkers in this cohort, suggesting that triclosan may affect thyroid homeostasis and autoimmunity.

Transcriptome and DNA Methylome Dynamics during Triclosan-Induced Cardiomyocyte Differentiation Toxicity

Cardiac development is a dynamic process and sensitive to environmental chemicals. Triclosan is widely used as an antibacterial agent and reported to transport across the placenta and affect embryonic development. Here, we used human embryonic stem cell- (hESC-) derived cardiomyocytes (CMs) to determine the effects of TCS exposure on cardiac development. After TCS treatment, the differentiation process was significantly blocked and spontaneous beating rates of CMs were also decreased. Transcriptome analysis showed the dysregulation of genes involved in cardiogenesis, including GATA4 and TNNT2. Additionally, DNA methylation was also altered by TCS exposure, especially in those regions with GATA motif enrichment. These alterations of transcriptome and DNA methylation were all associated with signaling pathways integral to heart development. Our findings indicate that TCS exposure might cause cardiomyocyte differentiation toxicity and provide the new insights into how environmental factors regulate DNA methylation and gene expressions during heart development.