Relationship between urinary triclosan and paraben concentrations and serum thyroid measures in NHANES 2007-2008

Association between multipollutant exposure and thyroid hormones in elderly people: A cross-sectional study in China

Environmental chemicals have been indicated to cause disruption of thyroid homeostasis in human populations. However, previous studies mostly focused on single group of chemicals. Herein, we investigate the independent and combined effects of multiple pollutants on thyroid homeostasis, including thyroid-stimulating hormone (TSH), total and free thyroxine (tT4 and fT4) and total and free triiodothyronine (tT3 and fT3) in elderly people. These environmental pollutants (n = 144) are from ten categories, including phenols, parabens, perfluoroalkyl substances (PFASs), polychlorinated biphenyls (PCBs), phthalate esters (PAEs), polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs), organophosphate pesticides (OPPs), synthetic pyrethroids (SPs), herbicides, and metals. Few studies have evaluated the health risks of these 144 chemicals, especially their joint effects. In single-pollutant evaluations, multiple linear regression (MLR) models were used to estimate the independent associations between multiple exposures and thyroid biomarkers. In multi-pollutant evaluations, elastic net regression and Bayesian kernel machine regression (BKMR) models were used to estimate the combined associations. The MLR models showed that 41 chemicals were significantly related to THs levels. BKMR models revealed the most important chemical groups: metals for TSH, PAHs, SPs and PCBs for tT4, herbicides and SPs for tT3. This study will contribute to the understanding of multipollutant exposure and help prioritize specific chemical groups related to thyroid hormone disruption.

Disruption of gonadotropin hormone biosynthesis by parabens: A potential development and reproduction-associated adverse outcome pathway

Parabens are widely used as antibacterial preservatives in foods and personal care products. The knowledge about the modes of toxic action of parabens on development and reproduction remain very limited. The present study attempted to establish a development and reproduction-associated adverse outcome pathway (AOP) by evaluating the effects of methylparaben (MP), ethylparaben (EP), propylparaben (PP) and butylparaben (BP) on the biosynthesis of gonadotropins, which are key hormones for development and reproduction. MP and BP significantly upregulated the mRNA and protein levels of follicle stimulating hormone (FSH) and luteinizing hormone (LH) in pituitary gonadotropic cells in a concentration-dependent manner. Activation of gonadotropin-releasing hormone receptor (GnRHR) was required for gonadotropin biosynthesis induced by BP, but not MP. Molecular docking data further demonstrated the higher binding efficiency of BP to human GnRHR than that of MP, suggesting GnRHR as a potential molecular initiative event (MIE) for BP-induced gonadotropin production. L-type voltage-gated calcium channels (VGCCs) were found to be another candidate for MIE in gonadotropic cells response to both MP and BP exposure. The calcium-dependent activation of extracellular signal-regulated kinase 1 (ERK1) and ERK2 was subsequently required for MP- and BP-induced activation of GnRHR and L-type VGCCs pathways. In summary, MP and BP promoted gonadotropin biosynthesis through their interactions with cellular macromolecules GnRHR, L-type VGCCs, and subsequent key event ERK1/2. This is the first study to report the direct interference of parabens with gonadotropin biosynthesis and establish a potential AOP based on pathway-specific mechanism, which contributes to the effective screening of environmental chemicals with developmental and reproductive health risks.

Exposure to endocrine disrupting chemicals (bisphenols, parabens, and triclosan) and their associations with preterm birth in humans

Preterm birth in humans (PTB), defined as birth prior to 37 weeks of gestation, is one of the most important causes of neonatal morbidity and mortality and is associated with adverse health outcomes later in life. Attributed to many different etiological factors, estimated 15.1 million or 11.1% of births each year are preterm, which is more than 1 per 10 livebirths globally. Environmental pollution is a well-established risk factor that could influence the pathogenesis of PTB. Increasing evidence has shown an association between maternal exposure to endocrine disrupting chemicals (EDCs) and PTB. This scoping review aims to summarize current research on the association between EDC exposure and PTB in humans. Database PubMed was used to identify articles discussing the effect of selected EDCs, namely bisphenol A, bisphenol S, bisphenol F, parabens, and triclosan, found in plastics, cosmetics and other personal care products, on PTB occurrence. Regardless of some inconsistences in the findings across studies, the reviewed studies suggest a potential association between involuntary exposure to reviewed EDCs and the risk of PTB. However, further studies are needed to delineate exact correlations and mechanisms through which EDC exposure causes PTB so that efficient preventative measures could be implemented. Until then, health care providers should inform women about possible EDC exposure thus empowering them to make healthy choices and at the same time decrease the EDC negative effects.

Evaluation of multiple organophosphate insecticide exposure in relation to altered thyroid hormones in NHANES 2007-2008 adult population

The thyroid gland is susceptible to chemical exposure such as organophosphate insecticides (OPIs). With the ubiquitous nature of these products, humans are simultaneously exposed to a multitude of chemicals. This study aimed to evaluate the association between an individual and a mixture of OPI metabolites and changes in serum thyroid hormone (TH) concentrations. The analyzed data were 1,434 participants from the United States National Health and Nutrition Examination Surveys (NHANES) cycle 2007-2008. Generalized linear model (GLM) regression, weighted quantile sum (WQS), and adaptive least absolute shrinkage and selection operator (adaptive LASSO) regression were used to investigate the associations between urinary OPI metabolites and altered serum THs. In GLM, all of the five urinary OPI metabolites were inversely associated with free triiodothyronine (FT3) among the male subjects; meanwhile, higher thyroglobulin (Tg) was related to dimethylphosphate (DMP). Moreover, in WQS models, the metabolite mixture induced FT3 down-regulation (β = -0.209 (95% CI: -0.310, -0.114)), and caused an increased Tg concentration (β = 0.120 (95% CI: 0.024, 0.212)), however, any significant association was observed among female participants. Consistently, the weighted index and LASSO coefficient demonstrated dimethylthiophosphate (DMTP) as the strongest metabolite in the FT3 model (mean weight= 3.449e-01 and β =-0.022, respectively), and dimethylphosphate (DMP) represented the highest association in the Tg model (mean weight= 9.873e-01 and β =-0.020, respectively). Further research is required to confirm our results and investigate the clinical impacts of these disruptions.

High-dose exposure to butylparaben impairs thyroid ultrastructure and function in rats

Parabens (PBs) are a class of preservatives commonly used in cosmetics and pharmaceuticals. Studies have shown that these compounds may act as endocrine disruptors, affecting thyroxine levels in humans. PBs with longer chain substituents, such as butylparaben (BuP), are less prone to complete biotransformation and are therefore more likely to accumulate in the body. In this study, the effect of high-dose exposure to BuP on thyroid microstructure, ultrastructure, and function was investigated in rats. 50 mg/kg bw per day of BuP was injected subcutaneously into the neck of rats for 4 weeks. Rat thyroid weight, microstructure, and ultrastructure were determined, and the levels of thyroid sodium/iodide symporter (NIS), serum thyroid hormones, and thyroid autoantibodies were measured. The human thyroid cell line was used to study the mechanism of BuP on thyroid epithelial cells. The weight of the thyroid gland of BuP-exposed rats was increased, the structure of the thyroid follicles was irregular and damaged, the mitochondria and rough endoplasmic reticulum were swollen and damaged, and the microvilli at the tip of the epithelium were reduced and disappeared. Serum total T3, total T4, free T3, and free T4 were decreased in BuP-exposed rats, and TSH, peroxidase antibody, and thyroglobulin antibody were increased. In vitro, BuP decreased the level of NIS in thyroid epithelial cells, inhibited proliferation and viability, and induced apoptosis in a dose-dependent manner. This study demonstrated that high-dose exposure to BuP induced structural, ultrastructural, and functional impairment to the thyroid gland of rats, which may be one of the factors leading to hypothyroidism.

Development of interpretable machine learning models associated with environmental chemicals to predict all-cause and specific-cause mortality：A longitudinal study based on NHANES

Limited information is available on potential predictive value of environmental chemicals for mortality. Our study aimed to investigate the associations between 43 of 8 classes representative environmental chemicals in serum/urine and mortality, and further develop the interpretable machine learning models associated with environmental chemicals to predict mortality. A total of 1602 participants were included from the National Health and Nutrition Examination Survey (NHANES). During 154,646 person-months of follow-up, 127 deaths occurred. We found that machine learning showed promise in predicting mortality. CoxPH was selected as the optimal model for predicting all-cause mortality with time-dependent AUROC of 0.953 (95%CI: 0.951-0.955). Coxnet was the best model for predicting cardiovascular disease (CVD) and cancer mortality with time-dependent AUROCs of 0.935 (95%CI: 0.933-0.936) and 0.850 (95%CI: 0.844-0.857). Based on clinical variables, adding environmental chemicals could enhance the predictive ability of cancer mortality (P < 0.05). Some environmental chemicals contributed more to the models than traditional clinical variables. Combined the results of association and prediction models by interpretable machine learning analyses, we found urinary methyl paraben (MP) and urinary 2-napthol (2-NAP) were negatively associated with all-cause mortality, while serum cadmium (Cd) was positively associated with all-cause mortality. Urinary bisphenol A (BPA) was positively associated with CVD mortality.

Associations between paraben exposure, thyroid capacity, homeostasis and pituitary thyrotropic function in the general Taiwanese: Taiwan Environmental Survey for Toxicants (TEST) 2013

Several studies have suggested that some endocrine disruptors such as synthetic phenols, parabens and phthalates may disrupt thyroid hormone signaling and associated negative feed-backs with the central hypothalamic-pituitary-thyroid (HPT) axis. Therefore, we investigated urinary paraben and blood thyroid hormone levels in the Taiwanese population. Our sample comprised 264 adults (aged 18-97 years) and 75 minors (aged 7-17 years) from Taiwan Environmental Survey for Toxicants 2013. Urinary levels of methylparaben (MeP), ethylparaben (EtP), propylparaben (PrP), and butylparaben (BuP) were assessed. Hormones of particular interest include: thyroid-stimulating hormone (TSH), triiodothyronine (T3), and thyroxine (T4). We sought integrated parameters to describe the transfer of thyroid hormones in homeostatic models. The geometric mean urinary paraben levels of the adults were higher than those of the minors (adults vs. minors; MeP: 383 vs. 62.4 ng/mL; PrP: 109 vs. 8.00 ng/mL; EtP: 39.5 vs. 2.38 ng/mL, and BuP: 6.36 vs. 2.13 ng/mL). In the male adults, we discovered that 0.253% (p = 0.032), 0.256% (p = 0.041) and 0.257% (p = 0.037) decreases in the TSH, TSH/T4 and TSH/FreeT4 ratio was associated with 1% EtP increases, respectively. In the female minors, 0.093% (p = 0.044), 0.072% (p = 0.047) and 0.156 (p = 0.004) increases in the TSH ratios were associated with a 1% MeP, EtP and BuP increase, respectively. Moreover, 0.151% (p = 0.008) and 0.177% (p = 0.001) increases in TSH/T4 and TSH/free T4 ratios were associated with a BuP 1% increase, respectively. Finally, EtP was positively associated with SPINA-GT (β: 15.66, p = 0.036) in the male adults. By contrast, EtP were positively associated with Jostel's TSH index and sTSHI (β: 0.072, p = 0.049; β: 0.107, p = 0.049) in the female minors. The Taiwanese population is commonly exposed to parabens, which can potentially lead to alteration of thyroid hormone homeostasis.

Sex-specific association of exposure to a mixture of phenols, parabens, and phthalates with thyroid hormone and antibody levels in US adolescents and adults

Individuals are exposed to multiple phenols, parabens, and phthalates simultaneously since they are important endocrine-disrupting compounds (EDCs) and share common exposure pathways. It is necessary to assess the effects of the co-exposure of these EDCs on thyroid hormones (THs). In this study, data included 704 adolescents and 2911 adults from the 2007-2012 National Health and Nutrition Examination Survey (NHANES). Serum THs measured total triiodothyronine (T3), total thyroxine (T4), free forms of T3 (FT3) and T4 (FT4), thyroid-stimulating hormone (TSH), thyroglobulin (Tg), thyroid peroxidase antibody (TPOAb), and thyroglobulin antibody (TgAb). And 16 EDCs (3 phenols, 2 parabens, and 11 phthalates) were measured from urine. The relationship between single EDCs and single THs was analyzed using generalized linear regression. And results showed that several EDCs were positively associated with serum T3 and FT3 levels in boys but negatively associated with serum T4 and FT4 levels in girls. And in adults, five EDCs were negatively associated with T3, T4, or FT4. The effects of co-exposure to 16 EDCs on THs were calculated using Bayesian kernel machine regression and quantile-based g-computational modeling, confirmed that co-exposure was related to the increase of T3 in adolescents and the decrease of T4 in both adolescents and adults. Besides, nonlinear and linear relationships were identified between co-exposure and the risk of positive TPOAb and TgAb in girls and adult females, respectively. In conclusion, phenols, parabens, and phthalates as a mixture might interfere the concentrations of THs and thyroid autoantibodies, and the interfering effect varies significantly by sex as well as by age. Further prospective research is warranted to investigate the causal effects and underlying mechanisms of co-exposure on thyroid dysfunction.

Environmental Endocrinology: Parabens Hazardous Effects on Hypothalamic-Pituitary-Thyroid Axis

Parabens are classified as endocrine-disrupting chemicals (EDCs) capable of interfering with the normal functioning of the thyroid, affecting the proper regulation of the biosynthesis of thyroid hormones (THs), which is controlled by the hypothalamic-pituitary-thyroid axis (HPT). Given the crucial role of these hormones in health and the growing evidence of diseases related to thyroid dysfunction, this review looks at the effects of paraben exposure on the thyroid. In this study, we considered research carried out in vitro and in vivo and epidemiological studies published between 1951 and 2023, which demonstrated an association between exposure to parabens and dysfunctions of the HPT axis. In humans, exposure to parabens increases thyroid-stimulating hormone (TSH) levels, while exposure decreases TSH levels in rodents. The effects on THs levels are also poorly described, as well as peripheral metabolism. Regardless, recent studies have shown different actions between different subtypes of parabens on the HPT axis, which allows us to speculate that the mechanism of action of these parabens is different. Furthermore, studies of exposure to parabens are more evident in women than in men. Therefore, future studies are needed to clarify the effects of exposure to parabens and their mechanisms of action on this axis.

Cetaceans as bio-indicators revealed the increased risks of triclosan exposure and associated thyroid hormone disruption during the COVID-19 pandemic

The global surge in disinfection practices from the COVID-19 response has raised concerns about the marine exposure to the hazardous ingredients in disinfectant products, including triclosan (TCS) and triclocarban (TCC). However, there are very limited studies on the response of marine TCS and TCC (TCs) loading to the COVID-19 pandemic. Here we used cetaceans as bio-indicators for a long-term retrospective analysis of TCs loading to the South China Sea (SCS) between 2004 and 2022. Hepatic TCs was 100% detected in all nine cetacean species (n = 120). Interestingly, TCS concentrations decreased in Indo-Pacific humpback dolphins (IPHD) before the pandemic from 2010 to 2017. However, after 2019, TCS concentrations in IPHD significantly increased several-fold. Similarly, post-pandemic TCS concentrations in Indo-Pacific finless porpoises (IPFP) and two fish species were significantly higher than pre-pandemic levels. There were significant relationships between thyroid hormones (THs) and TCs in IPHD and IPFP, suggesting that increased TCs may worsen the interference of THs homeostasis and nutritional conditions in cetaceans. These findings demonstrate the profound impact of the surging use of TCs-containing products from the COVID-19 response on marine ecosystems.

Exposure to parabens and semen quality in reproductive-aged men

BACKGROUND

Parabens are common preservatives in personal care products, cosmetics, and medical goods. In the past few years, animal studies showed the male reproductive toxicity associated with some parabens. Yet, epidemiological studies have generated inconsistent findings and research rarely has focused on the mixture effects of the parabens. We aimed to explore the associations between individual paraben exposure as well as the mixture and semen quality parameters.

METHODS

A total of 795 male partners from preconception couples were included in the study. Their urine samples were analyzed for the concentrations of six parabens, namely methyl paraben (MeP), ethyl paraben (EtP), propyl paraben (PrP), butyl paraben (BuP), benzyl paraben (BzP) and heptyl paraben (HeP). Multiple linear regression models and weighted quantile sum regression (WQS) models were utilized to assess the relationships between individual paraben exposure and paraben mixture with semen quality parameters, respectively.

RESULTS

After adjusting for covariates, exposure to a paraben mixture was significantly associated with declining sperm concentration, total sperm count, and progressive motility, among which BuP was identified as the main contributor to sperm concentration and total sperm count while MeP to progressive motility. Results from multiple linear regression models were generally in line with the WQS analysis.

CONCLUSIONS

Our results suggest negative associations between paraben mixture and sperm concentration, total sperm count, and sperm motility among reproductive-aged men.

Urinary Paraben Concentrations and Associations with the Periconceptional Urinary Metabolome: Untargeted and Targeted Metabolomics Analyses of Participants from the Early Pregnancy Study

BACKGROUND

Parabens, found in everyday items from personal care products to foods, are chemicals with endocrine-disrupting activity, which has been shown to influence reproductive function.

OBJECTIVES

This study investigated whether urinary concentrations of methylparaben, propylparaben, or butylparaben were associated with the urinary metabolome during the periconceptional period, a critical window for female reproductive function. Changes to the periconceptional urinary metabolome could provide insights into the mechanisms by which parabens could impact fertility.

METHODS

Urinary paraben concentrations were measured in paired pre- and postconception urine samples from 42 participants in the Early Pregnancy Study, a prospective cohort of 221 women attempting to conceive. We performed untargeted and targeted metabolomics analyses using ultrahigh-performance liquid chromatography quadrupole time-of-flight mass spectrometry. We used principal component analysis, orthogonal partial least-squares discriminant analysis, and permutation testing, coupled with univariate statistical analyses, to find metabolites associated with paraben concentration at the two time points. Potential confounders were identified with a directed acyclic graph and used to adjust results with multivariable linear regression. Metabolites were identified using fragmentation data.

RESULTS

Seven metabolites were associated with paraben concentration (variable importance to projection score > 1 , false discovery rate-corrected q -value < 0.1 ). We identified four diet-related metabolites to the Metabolomics Standards Initiative (MSI) certainty of identification level 2, including metabolites from smoke flavoring, grapes, and olive oil. One metabolite was identified to the class level only (MSI level 3). Two metabolites were unidentified (MSI level 4). After adjustment, three metabolites remained associated with methylparaben and propylparaben, two of which were diet-related. No metabolomic markers of endocrine disruption were associated with paraben concentrations.

DISCUSSION

This study identified novel relationships between urinary paraben concentrations and diet-related metabolites but not with metabolites on endocrine-disrupting pathways, as hypothesized. It demonstrates the feasibility of integrating untargeted metabolomics data with environmental exposure information and epidemiological adjustment for confounders. The findings underscore a potentially important connection between diet and paraben exposure, with applications to nutritional epidemiology and dietary exposure assessment. https://doi.org/10.1289/EHP12125.

Examining the association between urinary triclosan levels and menopausal status: results from the National Health and Nutrition Examination Survey, 2003 to 2016

OBJECTIVE

To examine the association between urinary levels of triclosan (TCS), a ubiquitous endocrine disrupter, and menopausal status using the National Health and Nutrition Examination Survey.

METHODS

A retrospective cross-sectional study from 2003 to 2016 was conducted among US female participants who completed the reproductive health questionnaire and provided TCS-level measurements. Exposure was assessed by urinary TCS levels adjusted for urinary creatinine; levels were log-transformed to achieve normal distribution for parametric analyses. Menopausal status was based on participants' responses to: "What is the reason that you have not had a period in the past 12 months?" Multivariable linear regression analyses examined the association between creatinine-adjusted urinary TCS levels and menopausal status after adjusting for age at survey completion, body mass index, race, ethnicity, and smoking exposure.

RESULTS

Of the final sample of female participants (n = 6,958), 40% identified as postmenopausal, of whom 60% had experienced natural menopause, and of these, 11% had become menopausal at under 40 years of age. Triclosan levels correlated positively with advancing age (r = 0.09, P < 0.001) and inversely with body mass index (r = -0.09, P < 0.001). Smoking exposure was associated with significantly lower TCS levels (P < 0.001). Compared with premenopausal women, postmenopausal women had significantly higher log-transformed, creatinine-adjusted TCS levels (mean, -1.22 ± 1.79 vs -1.51 ± 1.79 ng/mg creatinine; P < 0.001). Triclosan levels were unrelated to the duration of menopause and did not differ between women who underwent natural versus surgical menopause, and premature menopause versus menopause at 40 years or older. In unweighted multivariate linear regression analyses, menopausal status was independently associated with higher urinary TCS levels after adjusting for covariates (β coefficient, 0.17; 95% CI, 0.020-0.323; P = 0.026).

CONCLUSIONS

In a nationally representative sample, postmenopausal status was associated with higher urinary TCS levels, observations that merit further investigation into potential exposures and health consequences.

Associations between endocrine disruptor contamination and thyroid hormone homeostasis in Belgian type 1 diabetic children

PURPOSE

Humans are daily exposed to many environmental pollutants, some of which being suspected to be thyroid disruptors. Some populations could be particularly susceptible to thyroid disruption, such like diabetics due to the well-known relation between the thyroid function and the control of carbohydrate homeostasis by pancreas. Therefore, the aim of this study was to investigate the associations between the exposure to several persistent and non-persistent chemicals and thyroid hormones levels in children with type 1 diabetes.

METHODS

Blood and urine sample were collected from 54 children diagnosed for type 1 diabetes mellitus. The concentrations of 7 phthalate metabolites, 4 parabens, 7 bisphenols, benzophenone 3 and triclosan were measured in urine, while 15 organochlorine pesticides, 4 polychlorinated biphenyls (PCBs) and 7 perfluoroalkyl substances were analyzed in serum samples. In the same time, the blood levels of free thyroxine (fT4), thyroid stimulating hormone (TSH) and glycated hemoglobin (Hb1Ac) were determined.

RESULTS

We highlighted positive associations between serum perfluorohexane sulfonate and urinary monoethylphthalate levels, and TSH level in blood. We also found that PCB 138 was positively associated to fT4 while urinary levels of bisphenol F were negatively correlated to this hormone. Finally, we observed positive associations between Hb1Ac levels and the contamination by PCB 153 and two urinary phthalate metabolites: mono-2-ethyl-5-hydroxyhexyl phthalate and mono-2-ethyl-5-oxoxyhexyl phthalate.

CONCLUSION

Our results showed that our small cohort of children with type 1 diabetes mellitus is potentially susceptible to thyroid disruptions by some pollutants. Moreover, for these children, both di-(2-ethylhexyl) phthalate metabolites would potentially hamper the glucose homeostasis. Nevertheless, additional studies are mandatory to further explore these findings.

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.

Within-day variability, predictors, and risk assessments of exposure to parabens among Chinese adult men

BACKGROUND

Parabens, as suspected endocrine disruptors, are widely used in personal care products and pharmaceuticals. However, variability, predictors, and risk assessments of human exposure to parabens are not well characterized.

OBJECTIVE

To evaluate within-day variability, predictors, and risk assessments of exposure to parabens among Chinese adult men.

METHODS

We measured four parabens including methylparaben (MeP), ethylparaben (EtP), propylparaben (PrP), and butylparaben (BuP) in repeated urine samples from 850 Chinese adult men. We examined the variability by intraclass correlation coefficients (ICCs) and identified the predictors by multivariable linear mixed models. We assessed risks of paraben exposures based on the estimated daily intake (EDI).

RESULTS

The four parabens were detected in >76% of urinary samples. We observed fair to good to high reproducibility (ICCs: 0.71 to 0.86) for urinary paraben concentrations within one day. Use of facial cleanser was associated with higher four urinary paraben concentrations. Increasing age, taking medicine, intravenous injection, and interior decoration in the workplace were related to higher urinary concentrations of specific parabens. Smoking and drinking were associated with lower urinary concentrations of specific parabens. The maximum EDIs for the four parabens ranged from 13.76 to 848.68 μg/kg bw/day, and 0.9% of participants had the hazard quotient values > 1 driven by PrP exposure.

CONCLUSIONS

Urinary paraben concentrations were less variable within one day. Several lifestyle characteristics including use of facial cleanser and pharmaceuticals may contribute to paraben exposures.

Triclosan in paired-maternal and cord blood, and their relationships with congenital heart disease of baby

Prenatal triclosan (TCS) exposure has been reported to be associated with various birth outcomes and thyroid function, while the study of TCS exposure for congenital heart disease (CHD) patients is limited. In the present study, paired mother-fetus blood samples from CHD and healthy participants were collected to measure TCS exposure levels, and then check their relationship. Coupled with the concentrations of thyroid function biomarkers [free thyroxine (FT4), free triiodothyronine (FT3), thyroid-stimulating hormone (TSH), and thyroid antibodies (TgAb)] in maternal blood, we aimed to investigate whether the hormone-disrupting properties of TCS will affect its association with CHD. Our results indicated that the maternal TCS concentrations in the CHD group (median 0.31 ng/mL) were significantly lower than those in the control group (0.48 ng/mL, Mann Whitney U test, p = 0.01). Higher interquartile of TCS levels in maternal blood was associated with decrease odds of CHD (adjusted OR = 0.61, 95%CI: 0.41-0.91, p = 0.02). Maternal blood TCS higher than the cut-off value (25th quantile, 0.17 ng/mL) was significantly negatively associated with CHD risk (adjusted OR = 0.24, 95%CI: 0.09-0.62, p < 0.01). Besides, none of the thyroid biomarkers were significantly associated with maternal TCS exposure. However, maternal FT4 concentrations were positively correlated with TCS transplacental transfer rate and cord blood TCS levels (general linear regression, both p < 0.01). The results of molecular docking and dynamics simulation suggested that these correlations might be related to the transthyretin, a thyroid hormone-binding protein involved in the placental thyroid hormone transport system. Overall, our findings indicated that at normal exposure levels, the increase of maternal blood TCS concentration may have an inverse association with CHD, which merits further investigation.

Maternal paraben exposure and intra-pair thyroid-stimulating hormone difference in twin neonates

Thyroid hormones are essential for fetal growth and neurodevelopment. The recent frequent use of parabens has raised concerns about their endocrine-disrupting potential. However, the effects of maternal paraben exposure on neonatal thyroid hormone levels are still largely unknown. In our study, a co-twin control design was employed to analyze the relationships between maternal paraben exposure and neonatal thyroid-stimulating hormone (TSH) difference. We collected information from 252 mother-twin pairs from a twin birth cohort in Wuhan, China. Concentrations of six parabens were measured in maternal urine samples collected at < 16, 16-28, and > 28 weeks of gestation. Data of neonatal TSH levels were retrieved from medical records. Multiple informant models were applied to explore the time-specific relationships between paraben exposure and intra-twin TSH difference and to determine the susceptible window of exposure. We found that maternal urinary methyl paraben (MeP) during early pregnancy was positively associated with intra-twin TSH difference (%change = 5.96 %; 95 % confidant interval (CI): 0.04 %, 12.2 %). However, no significant differences were observed for exposure to ethyl paraben (EtP) and propyl paraben (PrP), and the associations between parabens and intra-twin TSH difference did not differ materially across pregnancy. Further, a stratified analysis based on twin zygosity and chorionicity and sex types indicated that the positive association between early pregnancy MeP exposure and intra-twin TSH difference was significant in monochorionic diamniotic (MCDA) twins of female-female fetuses and dichorionic diamniotic (DCDA) twins of opposite-sex. The prospective twin study provides first evidence that MeP exposure in early pregnancy was associated with an increased TSH difference in twin neonates, especially in female fetuses.

Urinary phenol concentrations and fecundability and early pregnancy loss

STUDY QUESTION

Are urinary phenol concentrations of methylparaben, propylparaben, butylparaben, triclosan, benzophenone-3, 2,4-dichlorophenol or 2,5-dichlorophenol associated with fecundability and early pregnancy loss?

SUMMARY ANSWER

2,5-dichlorophenol concentrations were associated with an increased odds of early pregnancy loss, and higher concentrations of butylparaben and triclosan were associated with an increase in fecundability.

WHAT IS KNOWN ALREADY

Phenols are chemicals with endocrine-disrupting potential found in everyday products. Despite plausible mechanisms of phenol reproductive toxicity, there are inconsistent results across few epidemiologic studies examining phenol exposure and reproductive function in non-fertility treatment populations.

STUDY DESIGN, SIZE, DURATION

Specimens and data were from the North Carolina Early Pregnancy Study prospective cohort of 221 women attempting to conceive naturally from 1982 to 1986. This analysis includes data from 221 participants across 706 menstrual cycles, with 135 live births, 15 clinical miscarriages and 48 early pregnancy losses (before 42 days after the last menstrual period).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Participants collected daily first-morning urine specimens. For each menstrual cycle, aliquots from three daily specimens across the cycle were pooled within individuals and analyzed for phenol concentrations. To assess sample repeatability, we calculated intraclass correlation coefficients (ICCs) for each phenol. We evaluated associations between phenol concentrations from pooled samples and time to pregnancy using discrete-time logistic regression and generalized estimating equations (GEE), and early pregnancy loss using multivariable logistic regression and GEE.

MAIN RESULTS AND THE ROLE OF CHANCE

ICCs for within-person variability across menstrual cycles in pooled phenol concentrations ranged from 0.42 to 0.75. There was an increased odds of early pregnancy loss with 2,5-dichlorophenol concentrations although the CIs were wide (5th vs 1st quintile odds ratio (OR): 4.79; 95% CI: 1.06, 21.59). There was an increased per-cycle odds of conception at higher concentrations of butylparaben (OR: 1.62; 95% CI: 1.08, 2.44) and triclosan (OR: 1.49; 95% CI: 0.99, 2.26) compared to non-detectable concentrations. No associations were observed between these endpoints and concentrations of other phenols examined.

LIMITATIONS, REASONS FOR CAUTION

Limitations include the absence of phenol measurements for male partners and a limited sample size, especially for the outcome of early pregnancy loss, which reduced our power to detect associations.

WIDER IMPLICATIONS OF THE FINDINGS

This study is the first to use repeated pooled measures to summarize phenol exposure and the first to investigate associations with fecundability and early pregnancy loss. Within-person phenol concentration variability underscores the importance of collecting repeated samples for future studies. Exposure misclassification could contribute to differences between the findings of this study and those of other studies, all of which used one urine sample to assess phenol exposure. This study also contributes to the limited literature probing potential associations between environmental exposures and early pregnancy loss, which is a challenging outcome to study as it typically occurs before a pregnancy is clinically recognized.

STUDY FUNDING/COMPETING INTEREST(S)

This research was supported by the National Institute of Environmental Health Sciences of the National Institutes of Health (award number F31ES030594), the Intramural Research Program of the National Institutes of Health, the National Institute of Environmental Health Sciences (project numbers ES103333 and ES103086) and a doctoral fellowship at the Yale School of Public Health. The authors declare they have no competing interests to disclose.

TRIAL REGISTRATION NUMBER

N/A.

Endocrine disruptor chemicals as obesogen and diabetogen: Clinical and mechanistic evidence

Obesity is becoming an inevitable pandemic all over the world. The World Obesity Federation predicts in the 2022 World Obesity Atlas that one billion people worldwide, including 1 in 5 women and 1 in 7 men, will be living with obesity by 2030. Moreover, the prevalence of diabetes is increasing worldwide, and diabetes is becoming more of a public health problem. Increased insulin resistance due to obesity and deficiency in insulin secretion are the two main causes of type 2 diabetes mellitus (T2DM). An exogenous chemical or mixture of chemicals that interferes with any aspect of hormone action was defined as endocrine-disrupting chemicals (EDCs). Bisphenol A (BPA), the first known EDC, was synthesized and was considered to be estrogenic. Global production of BPA has increased progressively from 5 to 8 million tons (MT) between 2010 and 2016. Furthermore, researchers estimated that the production should reach 10.2 MT by 2022. The human population is exposed to EDCs in daily life in such forms as pesticides/herbicides, industrial and household products, plastics, detergents, and personal care products. The term obesogen was used for chemicals that promote weight gain and obesity by increasing the number of adipocytes and fat storage in existing adipocytes, changing the energy balance, and finally regulating appetite and satiety. Besides the obesogenic effect, EDCs can cause T2DM through alteration in ß cell function and morphology and insulin resistance. In this review, we provide clinical and mechanistic evidence regarding EDCs as obesogen and diabetogen. However, those studies are not enough methodologically to indicate causality. In this respect, randomized clinical trials are needed to investigate the association between obesogen, diabetogen and the related metabolic clinical picture.

The association between hearing threshold and urinary personal care and consumer product metabolites in middle-aged and elderly people from the USA

Endocrine disruptors have been reported to be associated with hearing ability. However, the association between personal care and consumer product chemicals, known as commonly detected endocrine disruptors, and age-related hearing loss still remains unclear. This study aimed to examine the association between exposure to 7 personal care and consumer product chemicals and hearing thresholds in middle-aged and elderly people. A nationally representative cross-sectional study was performed. Eight hundred forty-five adults aged over 45 from the National Health and Nutrition Examination Survey (NHANES) were included in this study. Bayesian kernel machine regression (BKMR) and the k-medoid cluster analysis were used to evaluate the mixture effect of exposure to 7 chemicals on pure-tone average (PTA). Exposure to these chemicals was negatively associated with PTA. 2,5-Dichlorophenol had the greatest contribution to the mixture effect. The mixture effect was stronger in women, elderly people. Four pooled clusters were identified according to 7 chemicals exposures. Cluster 4 (high TCS exposure) showed a lower HFPTA (P = 0.00258) than cluster 3 (the lowest exposure cluster, as a reference). Our study provides evidence that exposure to personal care and consumer product chemicals might be inversely associated with PTA. More studies are needed to fully understand the association of exposure to these chemicals with hearing threshold.

Smartphone-based colorimetric determination of triclosan in aqueoussamples after ultrasound assisted-dispersive liquid-liquid microextraction under optimized response surface method conditions

In the present study, a simple and low cost methodology based on ultrasonic assisted-dispersive liquid-liquid microextraction (UA-DLLME) followed by smartphone-based colorimetric measurement was introduced for the separation and determination of Triclosan (TCS) from contaminated waters. This method is based on the formation of an azo compound from the alkaline reaction of TCS with a diazonium ion, resulting from the reaction of sodium nitrite and p-sulfanilic acid in an acidic medium. The orange-brown color product was extracted into a low volume of organic phase by UA-DLLME method and RGB values were recorded with free Android app Color Grab. The effective parameters in this procedure, namely solution pH, p-sulfanilic acid and nitrite concentration, reaction time and volume of the extraction solvent were investigated and optimized by response surface methodology (RSM) based on a Box-Behnken design (BBD) model. Under optimum conditions, the calibration graph was linear in the range of 3.0 and 200 μg L^-1 of TCS. The limit of detection (LOD) and limit of quantification (LOQ) were 0.8 and 2.7 μg L^-1, respectively. The proposed method was successfullyused for the analyses of triclosan in several water and wastewater samples and satisfactory results were obtained.

Risk of thyroid cancer and benign nodules associated with exposure to parabens among Chinese adults in Wuhan, China

Parabens are widely used as preservatives, which have been found to affect thyroid function in toxicological studies. However, population studies on whether they are associated with thyroid tumors remain unclear. This study aims to investigate the relationship between environmental paraben exposure and thyroid cancer and benign nodules. We recruited participants from the Department of Thyroid and Breast Surgery at Wuhan Central Hospital, Wuhan, China. The detectable percentages of methyl paraben, ethyl paraben, and propyl paraben in the urinary samples of 425 study subjects were 99.1%, 95.3%, and 92.0%, respectively. All uncorrected and creatinine-corrected parabens were moderately correlated with one another. After adjusting for possible confounders, all three parabens were associated with an increased risk of thyroid cancer. Furthermore, the mixture pollutant analysis of parabens found positive associations with risk of thyroid cancer (OR = 0.24, 95% CI: 0.18, 0.31) and benign nodules (OR = 1.33, 95% CI: 0.86, 1.80). We observed that individual exposure to paraben mixtures may be associated with the risk of thyroid cancer and benign nodules.

Triclosan and Its Consequences on the Reproductive, Cardiovascular and Thyroid Levels

Hygiene is essential to avoid diseases, and this is thanks to daily cleaning and disinfection habits. Currently, there are numerous commercial products containing antimicrobial agents, and although they are efficient in disinfecting, it is still not known the effect of the constant use of these products on human health. In fact, a massive use of disinfectants has been observed due to COVID-19, but the possible adverse effects are not yet known. Triclosan is one of the antimicrobial agents used in cosmetic products, toothpaste, and disinfectants. This compound is an endocrine disruptor, which means it can interfere with hormonal function, with its estrogenic and androgenic activity having already been stated. Even if the use of triclosan is well-regulated, with the maximum allowed concentration in the European Union of 0.3% (m/m), its effects on human health are still uncertain. Studies in animals and humans suggest the possibility of harmful health outcomes, particularly for the reproductive system, and in a less extent for the cardiovascular and thyroid functions. Thus, the purpose of this review was to analyse the possible implications of the massive use of triclosan, mainly on the reproductive and cardiovascular systems and on the thyroid function, both in animals and humans.

Association between parabens concentrations in human amniotic fluid and the offspring birth size: A Sub-study of the PERSIAN birth cohort

OBJECTIVE

Parabens are extensively used, and cause widespread exposure of the general population including pregnant women and developing fetuses to these pollutants. In this study, we aimed to investigate the association between the maternal exposure of parabens to study their transfer passed through the placental barrier to amniotic fluid; the second objective was to determine the association of paraben concentration in the amniotic fluid with the offspring birth size.

METHODS

This cross-sectional study was conducted from June 2019 to March 2021 in Isfahan, Iran. Samples of amniotic fluid were collected as set from 128 pregnant women at Cesarean section. The amniotic fluid concentrations of four parabens including methylparaben (MP), ethylparaben (EP), propylparaben (PP), and butylparaben (BP) were determined using gas chromatography tandem mass spectroscopy (GC-Mass).

RESULTS

The pointed parabens were extracted from yielded clear supernatant using a dispersive liquid-liquid microextraction (DLLME) method. Four paraben derivatives including MP (normal: 0.68 ± 0.7; overweight: 1.40 ± 1.76; obese: 0.30 ± 0.26; p-value: 0.275), EP (normal: 0.14 ± 0.09; overweight: 0.72 ± 0.72; obese: 0.38 ± 0.05; p-value: 0.434), PP (normal: 0.05 ± 0.05; overweight: 0.06 ± 0.06; obese: 0.20 ± 0.17; p-value: 0.770), and BP (normal: 2.89 ± 1.80; overweight: 3.89 ± 6.48; obese: 5.80 ± 7.56; p-value: 0.341) were simultaneously detected in samples of maternal amniotic fluid using GC-MS. In 92.2% (n = 118) of pregnant women, the paraben derivatives (MP, EP, PP, BP) were detected. We found that considerable levels of MP, EP, PP, and BP existed in 22.6% (n = 29), 21.9% (n = 28), 29.7% (n = 38), and 85.2% (n = 109) of samples, respectively. In addition, the correlation between paraben concentrations in amniotic fluid and birth size was investigated. The results showed that an inverse significant association between MP and head circumference, chest, hip, and arm circumference. While a positive correlation between MP and height of newborn was observed. Similar correlations were observed for EP and weight, height, head circumference, chest, hip, and arm.

CONCLUSION

The current study indicated that parabens have been detected in amniotic fluid samples and a strong/possible correlation between exposure of pregnant women to parabens and the birth size of newborns.

Halogenated ingredients of household and personal care products as emerging endocrine disruptors

The everyday use of household and personal care products (HPCPs) generates an enormous amount of chemicals, of which several groups warrant additional attention, including: (i) parabens, which are widely used as preservatives; (ii) bisphenols, which are used in the manufacture of plastics; (iii) UV filters, which are essential components of many cosmetic products; and (iv) alkylphenol ethoxylates, which are used extensively as non-ionic surfactants. These chemicals are released continuously into the environment, thus contaminating soil, water, plants and animals. Wastewater treatment and water disinfection procedures can convert these chemicals into halogenated transformation products, which end up in the environment and pose a potential threat to humans and wildlife. Indeed, while certain parent HPCP ingredients have been confirmed as endocrine disruptors, less is known about the endocrine activities of their halogenated derivatives. The aim of this review is first to examine the sources and occurrence of halogenated transformation products in the environment, and second to compare their endocrine-disrupting properties to those of their parent compounds (i.e., parabens, bisphenols, UV filters, alkylphenol ethoxylates). Albeit previous reports have focused individually on selected classes of such substances, none have considered the problem of their halogenated transformation products. This review therefore summarizes the available research on these halogenated compounds, highlights the potential exposure pathways, and underlines the existing knowledge gaps within their toxicological profiles.

Prenatal exposure to parabens in association with cord serum adipokine levels and offspring size at birth

BACKGROUND

Paraben exposure is linked to the release of adipokine such as leptin and adiponectin, and both paraben and adipokine may affect fetal growth. The present study aimed to explore the associations among maternal paraben exposure, adipokine level and offspring size.

METHODS

942 mother-newborn pairs from the Sheyang Mini Birth Cohort Study (SMBCS) were enrolled. Data of birth weight, length, head circumference and ponderal index (PI) were obtained from medical records. Maternal urinary parabens were determined by gas chromatography tandem mass spectrometry. Cord serum leptin and adiponectin were measured using ELISA assay. Generalized linear regression was applied to explore the associations among parabens, adipokines and offspring size.

RESULTS

The median levels of leptin and adiponectin were 13.13 μg/L and 161.82 μg/mL. Benzylparaben level was positively associated with leptin (regression coefficient (β) = 0.06, 95% confidence interval (CI): 0.03-0.09; p < 0.01). Leptin level was positively associated with neonatal weight (β = 84.11, 95% CI: 63.22-105.01; p < 0.01), length (β = 0.25, 95% CI: 0.14-0.37; p < 0.01), head circumference (β = 0.15, 95% CI: 0.07-0.22; p < 0.01) and PI (β = 0.23, 95% CI: 0.08-0.39; p < 0.01). Adiponectin was positively associated with neonatal weight (β = 75.94, 95% CI: 29.65-122.23; p < 0.01) and PI (β = 0.43, 95% CI: 0.09-0.77; p = 0.01). Urinary propylparaben concentration (β = -0.10, 95% CI: -0.17 to -0.02; p = 0.01) was negatively associated with head circumference. Sex-stratified analyses indicated the negative association of propylparaben and head circumference was only remained in male neonates.

CONCLUSIONS

Prenatal paraben exposure might affect cord serum leptin levels. Both paraben and adipokine levels may affect fetal growth, and sex-specific differences may exist.

Effect of Triclosan and Silver Nanoparticles on DNA Damage Investigated with DNA-Based Biosensor

Triclosan (TCS) is a broad-spectrum antimicrobial agent widely used in personal care, healthcare, and clinical practice. One of the most important aspects of toxicological profiling of compounds is their interaction with DNA. In human cells, TCS causes a significant reduction in DNA methylation. The involvement of TCS in chromosomal aberrations, DNA damage, and strand breaks, as well as DNA damage from TCS degradation products, was reported. AgNPs share similarities with TCS in terms of antimicrobial properties, enter the body after exposure, and are used even together with TCS in oral care products. Therefore, their mutual effect on the DNA is of interest. In this study, the electrochemical behavior of TCS on a glassy carbon electrode (GCE) and the biosensor with salmon sperm dsDNA (DNA/GCE), DNA damage by TCS present in phosphate buffer solution pH 7.4 and an additional effect of the immobilized AgNP layer on such DNA damage have been investigated. Two different sizes of AgNPs (about 15 and 37 nm) were tested. Using square-wave voltammetric signals of nucleobases, the portion of survived DNA was 64% in the presence of 15 nm AgNPs compared to 55% in its absence. The protective effect of AgNPs on DNA against TCS-induced DNA damage was found.

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.

Patterns of environmental exposure to phenols in couples who plan to become pregnant

Phenols are widely used in consumer products and known for their reproductive toxicities. Little is known regarding the environmental exposure to phenols in couples prior to conception, a key period affecting fertility. We measured the urinary concentrations of six parabens and seven bisphenols in 903 pre-conception couples in China. We investigated the occurrence, distribution, source and health risk of phenols in husbands and wives separately, and the correlation and difference in phenol concentrations between couples. Similar distribution profiles of urinary phenols were observed between females and males. Methyl 4-hydroxybenzoate (MeP) and bisphenol A (BPA) were the predominant compounds. The level of urinary phenols in our population was mostly lower than the global levels. Exposure to phenols was linked to processed food and personal care products. The correlations between phenols in males and females were moderate (0.218-0.686), while the correlation in phenols between husband and wife was low (0.009-0.215). Female had a significantly higher urinary phenol levels than male (P < 0.05). Urinary phenols in couples were associated with family income, type of drinking water and frequency of household cleaning. Household factors accounted for ≤1.5% of variance in phenol levels between couples, suggesting that individual variations may be the major factor. Risk assessment showed that exposure to phenols posed a low hazard to 17.5% of the couples in our population. Our findings provide important evidence of environmental exposure to phenols in couples of child-bearing age.

Association between exposure to parabens and total mortality in US adults

BACKGROUND

Parabens are a group of endocrine disruptors that have been associated with health effects such as hypertension, diabetes, oxidative stress and obesity, which are associated with increased mortality risk over time. Women are exposed to higher paraben levels than men through use of consumer products. The current prospective study examines paraben exposure in association with mortality risk for women and men.

METHODS

We analyzed 2005-2008 National Health and Nutrition Examination Survey (NHANES) data on urinary paraben analyte concentrations and covariates in adults aged 20 years and over, prospectively linked to National Center for Health Statistics (NCHS) mortality through 2015 (N = 2939). Proportional hazard regression models examined mortality risk in association with exposures, controlling for covariates for women and men. Covariates included age, race/ethnicity, smoking, education, income, body mass index, physical activity, self-reported health status and baseline health conditions.

RESULTS

Women were exposed to significantly higher concentrations of all studied parabens than men. Exposures were highest for methyl paraben. Women had significantly higher mortality risk in association with higher natural log exposure to ethyl (HR = 2.048, 95% CI 1.164-3.601), methyl (HR = 1.312, 95% CI 1.013-1.700), butyl (HR = 2.719, 95% CI 1.591-4.647) and total parabens (HR = 1.292, 95% CI 1.006-1.659). Exposure concentrations were associated with higher mortality risk for men only for ethyl paraben (HR = 2.532, 95% CI 1.217-5.268).

DISCUSSION

Women were found to be at greater mortality risk in association with exposure to ethyl, methyl, butyl and total parabens. These findings require confirmatory research but add to the evidence base that exposure to parabens, probably through consumer products, may have adverse effects on human health, especially for women.

Several typical endocrine-disrupting chemicals in human urine from general population in China: Regional and demographic-related differences in exposure risk

Endocrine-disrupting chemicals (EDCs) are ubiquitous in the environment, and human exposure to these pollutants has caused great public concern. Five groups of EDCs, including parabens, antimicrobials (triclosan (TCS) and triclocarban (TCC)), bisphenols (BPs), tetrabromobisphenol A and its alternatives (TBBPAs), and benzophenones, in urines of general populations from three cities with different economic levels in China were determined simultaneously to evaluate the coexposure levels of such chemicals. The total concentration of target compounds was approximately two times higher in the urines from Chengdu (a first-tier city; geometric mean: 2.50 μg/L) than that from Nantong (a second-tier city; 1.34 μg/L), and was one order of magnitude higher than that from Shehong (a fifth-tier city; 0.73 μg/L). Urinary target compounds were significantly correlated with gender, age, body mass index (BMI), education level, occupation, and diet. The estimated daily intakes of target chemicals ranged from 0.002 (benzophenones) to 10.2 µg/kg-bw/day (parabens). The exposure estimate showed that females were more vulnerable to exposure to these EDCs. This study profiles the regional and demographic-related differences in the concentrations and exposure risks of several typical EDCs in urines from general populations in three cities with different economic levels in China.

Developmental Phenotypic and Transcriptomic Effects of Exposure to Nanomolar Levels of 4-Nonylphenol, Triclosan, and Triclocarban in Zebrafish (Danio rerio)

Triclosan, triclocarban and 4-nonylphenol are all chemicals of emerging concern found in a wide variety of consumer products that have exhibited a wide range of endocrine-disrupting effects and are present in increasing amounts in groundwater worldwide. Results of the present study indicate that exposure to these chemicals at critical developmental periods, whether long-term or short-term in duration, leads to significant mortality, morphologic, behavioral and transcriptomic effects in zebrafish (Danio rerio). These effects range from total mortality with either long- or short-term exposure at 100 and 1000 nM of triclosan, to abnormalities in uninflated swim bladder seen with long-term exposure to triclocarban and short-term exposure to 4-nonylphenol, and cardiac edema seen with short-term 4-nonylphenol exposure. Additionally, a significant number of genes involved in neurological and cardiovascular development were differentially expressed after the exposures, as well as lipid metabolism genes and metabolic pathways after exposure to each chemical. Such changes in behavior, gene expression, and pathway abnormalities caused by these three known endocrine disruptors have the potential to impact not only the local ecosystem, but human health as well.

Assessment of Thyroid Endocrine Disruption Effects of Parabens Using In Vivo, In Vitro, and In Silico Approaches

The extensive applications of parabens in foods, drugs, and cosmetics cause inevitable exposure to humans. Revealing the developmental toxicity of parabens is of utmost importance regarding their safety evaluation. In this study, the effects of four commonly used parabens, including methyl paraben (20 ∼ 200 μM), ethyl paraben (20 ∼ 100 μM), propyl paraben (5 ∼ 20 μM), and butyl paraben (BuP, 2 ∼ 10 μM), were investigated on the early development of zebrafish embryos and larvae. The underlying mechanisms were explored from the aspect of their disturbance in the thyroid endocrine system using in vivo, in vitro, and in silico assays. Paraben exposure caused deleterious effects on the early development of zebrafish, with BuP displaying the highest toxicity among all, resulting in the exposure concentration-related mortality, decreased hatching rate, reduced body length, lowered heart rate, and the incidence of malformation. Further investigation showed that paraben exposure reduced thyroid hormone levels and disturbed the transcriptional expressions of the target genes in the hypothalamic-pituitary-thyroid axis. Molecular docking analysis combined with in vitro GH3 cell proliferation assay testified that all test parabens exhibited thyroid receptor agonistic activities. The findings confirmed the developmental toxicity of the test parabens and their thyroid endocrine disruption effects, providing substantial evidence on the safety control of paraben-based preservatives.

Exposure of men and lactating women to environmental phenols, phthalates, and DINCH

Phthalates and 1,2-Cyclohexane dicarboxylic acid diisononyl ester (DINCH), bisphenols (BPs), parabens (PBs), and triclosan (TCS) are high-production-volume chemicals of pseudo-persistence that are concerning for the environment and human health. This study aims to assess the exposure to 10 phthalates, DINCH, and environmental phenols (3 BPs, 7 PBs, and TCS) of Slovenian men (n = 548) and lactating primiparous women (n = 536). We observed urinary concentrations comparable to studies from other countries and significant differences among the sub-populations. In our study, men had significantly higher levels of phthalates, DINCH, and BPs, whereas the concentrations of PBs in urine were significantly higher in women. The most significant determinant of exposure was the area of residence and the year of sampling (2008-2014) that mirrors trends in the market. Participants from urban or industrialized sampling locations had higher levels of almost all monitored analytes compared to rural locations. In an attempt to assess the risk of the population, hazard quotient (HQ) values were calculated for individual compounds and the chemical mixture. Individual analytes do not seem to pose a risk to the studied population at current exposure levels, whereas the HQ value of the chemical mixture is near the threshold of 1 which would indicate a higher risk. We conclude that greater emphasis on the risk resulting from cumulative exposure to chemical mixtures and additional studies are needed to estimate the exposure of susceptible populations, such as children.

The Influence of Triclosan on the Thyroid Hormone System in Humans - A Systematic Review

OBJECTIVES

Triclosan is an antibacterial agent suspected to disrupt the endocrine system. The aim of this study was to investigate the influence of triclosan on the human thyroid system through a systematic literature review of human studies.

METHODS

Eligibility criteria and method of analysis were registered at Prospero (registration number: CRD42019120984) before a systematic search was conducted in Pubmed and Embase in October 2020. Seventeen articles were found eligible for inclusion. Thirteen studies were observational, while four had a triclosan intervention. Participants consisted of pregnant women in eight studies, of men and non-pregnant women in seven studies and of chord samples/newborns/children/adolescents in six studies. The outcomes were peripheral thyroid hormones and thyroid-stimulating hormone (TSH) in blood samples.

RESULTS

Several studies found a negative association between triclosan and triiodothyronine and thyroxine, and a positive association with TSH; however, the opposite associations or no associations were also found. In general, the studies had limited measurement timepoints of thyroid outcomes, and the interventional studies used low concentrations of triclosan. Thus, study design limitations influence the quality of the dataset and it is not yet possible to conclude whether triclosan at current human exposure levels adversely affects the thyroid hormone system.

CONCLUSIONS

Further larger studies with more continuity and more elaborate outcome measurements of thyroid function are needed to clarify whether triclosan, at current exposure levels, affects the human thyroid hormone system.

SYSTEMATIC REVIEW REGISTRATION

http://www.crd.york.ac.uk/PROSPERO/display_record.asp?ID=CRD42019120984, identifier PROSPERO (CRD42019120984).

Risk of breast cancer and prediagnostic urinary excretion of bisphenol A, triclosan and parabens: The Multiethnic Cohort Study

Exposure to bisphenol A (BPA), triclosan and parabens is widespread but their impact on breast cancer risk remains unclear. This nested case-control study investigated endocrine-disrupting chemicals (EDCs) and breast cancer risk within the Multiethnic Cohort (MEC). We measured prediagnostic urinary BPA, triclosan and parabens in 1032 postmenopausal women with breast cancer (48 African American, 77 Latino, 155 Native Hawaiian, 478 Japanese American and 274 White) and 1030 individually matched controls, using a sensitive and validated liquid chromatography mass spectrometry assay. Conditional logistic regression was used to examine risk with these EDCs with adjustment for creatinine and potential confounders. In all women, breast cancer risk was not associated with BPA (Ptrend  = 0.53) and was inversely associated with triclosan (ORT3 vs T1  = 0.83, 95% CI: 0.66-1.04, Ptrend  = 0.045) and total parabens (ORT3 vs T1  = 0.77, 95% CI: 0.62-0.97, Ptrend  = 0.03). While risk of hormone receptor positive (HR+) cancer was 20% to 23% lower among women in the upper two tertiles of paraben exposure (Ptrend  = 0.02), risk of HR negative (HR-) was reduced 27% but only among those in the upper tertile of exposure. Although risk associations did not differ significantly by ethnicity or by body mass index (BMI), the inverse association with triclosan was observed mainly among overweight/obese women (ORT3 vs T1  = 0.76, 95% CI: 0.56-1.02, Ptrend  = 0.02). In summary, breast cancer risk in a multiethnic population was unrelated to BPA and was weakly inversely associated with triclosan and paraben exposures. Studies with multiple urine samples collected before breast cancer diagnosis are needed to further investigate these EDCs and breast cancer risk.

Occurrence of parabens, triclosan and triclocarban in paired human urine and indoor dust from two typical cities in China and its implications for human exposure

Parabens, triclosan (TCS) and triclocarban (TCC) are emerging endocrine disrupting chemicals, which are commonly used in personal care products and household applications in daily life. Due to their adverse health effects, human exposure to these chemicals has been a public concern. Despite evidence showing different exposure pathways of these chemicals, few studies have examined contribution of certain exposure to total human exposure. In this study, we measured six parabens, TCS and TCC in 129 indoor dust samples and these chemicals plus four paraben metabolites in 203 urine samples from two different cities in China (Suizhou, a typical small city in central China and Beijing, the capital of China). The median concentrations of ∑₆Parabens (1050 ng/g) and ∑TCS + TCC (565 ng/g) in dusts from Beijing were 1.9-3.3 times higher than those from Suizhou (∑₆Parabens: 314, ∑TCS + TCC: 294 ng/g). The ∑₆Parabens in urines from Suizhou and Beijing were in the range of 0.208-645 and 0.455-2300 μg/g Creatinine (Cr), respectively. The ∑TCS + TCC concentrations in urine were 1-2 orders of magnitude lower than those found for ∑₆Parabens. Comparatively, women had relatively higher body burden of parabens than men, which was more noticeable when considering the use of skin care products. In this regard, relatively higher levels of parabens were also found in women in couples. Positive correlations were found between concentrations of methyl-paraben (MeP) and ethyl-paraben (PrP) in paired dust and urine samples (p < 0.05). Human exposure to such chemicals was evaluated. Based on the measured concentrations in paired human urine and indoor dust samples, our results provided direct evidence that the contribution of indoor dust ingestion to the total exposure was minor. These findings are essential for clarifying the sources and potential exposure routes of these chemicals in humans.

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.

Review of the safety of application of cosmetic products containing parabens

Cosmetics are a source of lifetime exposure to various substances including parabens, being the most popular synthetic preservatives. Because the use of cosmetics shows an increasing trend and some adverse health outcomes of parabens present in these products have been reported, the present review focused on the safety of dermal application of these compounds. Special attention has been paid to the absorption of parabens and their retention in the human body in the intact form, as well as to their toxicological characteristics. Particular emphasis has been placed on the estrogenic potential of parabens. Based on the available published data of the concentrations of parabens in various kinds of cosmetics, the average ranges of systemic exposure dose (SED) for methylparaben, ethylparaben, propylparaben, and butylparaben have been calculated. Safety evaluations [margin of safety (MoS)] for these compounds, based on their aggregate exposure, have also been performed. Moreover, evidence for the negative impact of methylparaben on skin cells has been provided, and the main factors that may intensify dermal absorption of parabens and their impact on the skin have been described. Summarizing, the use of single cosmetics containing parabens should not pose a hazard for human health; however, using excessive quantities of cosmetic preparations containing these compounds may lead to the development of unfavorable health outcomes. Due to the real risk of estrogenic effects, as a result of exposure to parabens in cosmetics, simultaneous use of many cosmetic products containing these preservatives should be avoided.

The sex-specific association between maternal urinary paraben levels and offspring size at birth

Parabens are a group of antimicrobial preservatives applied in an extensive range of products and are suspected to impair fetal growth because of their disrupting effect on the endocrine system. We aimed to examine maternal urinary paraben concentrations and their neonates' outcome indexes. Methylparaben (MP), ethylparaben (EP), propylparaben (PP), and butylparaben (BP) concentrations were measured in 105 maternal urine samples collected before delivery. Length, weight, and head circumference at birth were extracted from the mothers' delivery files. A multivariable linear regression analysis was performed to evaluate the association between paraben levels and neonatal anthropometric indices. The median levels of urinary parabens, especially BP, were higher than those in other countries. Prenatal urinary concentration of MP and BP showed a significantly positive association with birth weight in all neonates (β = 0.79, 95% CI: 0.16, 1.41, and β = 8.56, 95% CI: 3.95, 13.17, respectively), while these chemicals showed a significant negative association with head circumference (β = - 0.002, 95% CI: - 0.004, - 0.000, and β = - 0.016, 95% CI: - 0.030, - 0.002, respectively). A significant positive association between MP and birth length was also found (β = 0.004, 95% CI: 0.00, 0.00) in all the neonates. In sex-stratified adjusted models, MP and BP were found to be associated, respectively, with higher birth length and weight in male neonates (β = 0.008, 95% CI: - 0.001, 0.017, and β = 7.948, 95% CI: 1.045, 14.851). In girls, maternal urinary MP, PP, and BP were associated with increased birth weight (β = 0.831, 95% CI: 0.043, 1.620; β = 4.178, 95% CI: 0.877, 7.480; and β = 10.821, 95% CI: 3.545, 18.097, respectively), and MP and BP were associated with reduced head circumference at birth (β = - 0.003, 95% CI: - 0.005, - 0.001, and β = - 0.035, 95% CI: - 0.055, - 0.016). These results revealed potential impacts between neonatal growth and maternal exposure to parabens. However, these findings should be interpreted while considering the limitations of the present study.

Controversy around parabens: Alternative strategies for preservative use in cosmetics and personal care products

Parabens usage as preservatives in cosmetics and personal care products have been debated among scientists and consumers. Parabens are easy to production, effective and cheap, but its safety status remains controversial. Other popular cosmetics preservatives are formaldehyde, triclosan, methylisothiazolinone, methylchloroisothiazolinone, phenoxyethanol, benzyl alcohol and sodium benzoate. Although their high antimicrobial effectiveness, they also exhibit some adverse health effects. Lately, scientists have shown that natural substances such as essential oils and plant extracts present antimicrobial potential. However, their use in cosmetic is a challenge. The present review article is a comprehensive summary of the available methods to prevent microbial contamination of cosmetics and personal care products, which can allow reducing the use of parabens in these products.

Assessment of the endocrine-disrupting potential of halogenated parabens: An in silico approach

Parabens are endocrine-disrupting chemicals present in a variety of pharmaceutical and personal care products. Due to their wide-spread use, significant amounts are also released into the aquatic domain of the environment. During water disinfection, parabens give rise to halogenated transformation products. As opposed to parabens, there is considerable lack of knowledge with regard to the endocrine-disrupting potential of their halogenated counterparts, which presents a challenge for regulatory decision making. We aimed to fill this knowledge gap by using the Endocrine Disruptome and VirtualToxLab™ to predict their endocrine-disrupting potential on the basis of calculated affinities for different nuclear receptors. The applied computational approach indicates a high probability of halogenated parabens binding to glucocorticoid, thyroid and aryl hydrocarbon receptors and suggests that disinfection is likely to form transformation products with more pronounced endocrine-disrupting activities than those of parent parabens. The obtained results not only highlight the need for additional in vitro/in vivo investigations of these chemicals as endocrine disruptors but also provide a means of guiding and prioritizing these future studies, in order to assess fully their hazard to human health.

Young children's exposure to phenols in the home: Associations between house dust, hand wipes, silicone wristbands, and urinary biomarkers

BACKGROUND

Environmental phenols, such as parabens, bisphenol A, and triclosan, are ubiquitous in indoor environments because of their use in packaging, plastics, personal care products, and as anti-microbials. The primary pathways of exposure, as well as habits and behaviors that may lead to greater exposure, are still unclear.

OBJECTIVES

Herein, we investigate the relationships between phenols found in residential environments by comparing levels in paired samples of house dust and hand wipes with children's urine. In addition, phenols were analyzed in a novel exposure tool, the silicone wristbands, to investigate which external matrix best correlates with individual exposure based on urinary phenol biomarkers.

METHODS

Children aged 3-6 years in central North Carolina, United States, provided paired hand wipe (n = 202), wristband (n = 76), and spot urine samples (n = 180), while legal guardians completed questionnaires on habits and behaviors. House dust samples (n = 186) were collected from the main living area during home visits completed between 2014 and 2016.

RESULTS

Environmental phenols were detected frequently in all matrices investigated. Ethyl, methyl, and propylparaben levels observed in hand wipes, dust, and on wristbands were significantly correlated to their associated urinary biomarkers. In addition, intra-paraben correlations were noted, with biomarkers of ethyl, methyl, and propylparabens generally positively and significantly correlated, which suggests co-application of parabens in products. Triclosan levels in dust were positive and significantly correlated with levels in hand wipes and wristbands and with urinary concentrations, suggesting non-personal care product sources may be important in children's overall triclosan exposure. Generally, chemicals on wristbands were more highly correlated with urinary biomarkers than with chemicals in hand wipes or house dust. In addition, more frequent lotion use was positively associated with urinary concentrations of paraben biomarkers.

CONCLUSIONS

Our results suggest that the home environment is an important source of exposure which has been under-investigated for some environmental phenols (e.g., triclosan in house dust). Associations between wristbands and biomarkers of exposure, which were stronger than for hand wipes and house dust, suggest that silicone wristbands may provide a suitable exposure assessment tool for some phenols.

Associations among urinary triclosan and bisphenol A concentrations and serum sex steroid hormone measures in the Canadian and U.S. Populations

Exposure to triclosan, an antimicrobial agent, and bisphenol A (BPA), the monomer of polycarbonate plastics, is widespread. Endocrine-disrupting impacts of these chemicals have been demonstrated in in vitro studies, rodent toxicology studies, and some human observational studies. Here we compared urinary concentrations of triclosan and BPA in the Canadian and U.S. populations using nationally-representative data from the 2012-2015 Canadian Health Measures Survey (CHMS) and the 2013-2016 National Health and Nutrition Examination Survey (NHANES). We then examined the cross-sectional associations of urinary triclosan or BPA with serum sex steroid hormones, including estradiol (E2), progesterone (P4), and testosterone (T), using multivariable regression. We observed differences in creatinine-standardized chemical concentrations between countries; urinary triclosan was higher in Canadian females aged 12-19 years, while BPA was higher in U.S. females aged 20-49 years. We also found significant associations among urinary chemicals and serum E2 and T, but not P4. Increasing triclosan was associated with higher levels of E2 in 6-11-year-old girls, but with lower levels of E2 and T in adolescent boys aged 12-19 years. Increasing BPA was associated with lower levels of E2 in 6-11-year-old boys and in adolescents aged 12-19 years of either sex. We observed a U-shaped association between urinary triclosan and E2 in male adults aged 50-79 years; no associations between BPA and hormones were detected in adults. These results, in accordance with the in vitro and animal literature, suggest that triclosan and BPA exposures may be cross-sectionally associated with altered reproductive hormone levels, especially in children and adolescents. Further research and prospective studies are necessary to elucidate country-specific differences in chemical exposures and the potential public health significance of these findings.

Urinary concentrations of parabens amongst Iranian adults and their associations with socio-demographic factors

BACKGROUND

Parabens are widely used to prevent organism growth and increase the shelf life of foods, medicines and personal care products (PCPs). Recent studies indicate their potentially harmful effects on human health. There is no information on the extent of exposure to parabens among Iranians.

METHODS

We measured the concentration of urinary methylparaben (MP), ethylparaben (EP), propylparaben (PP) and butylparaben (BP) among Iranian adults and calculated their estimated daily intake (EDI). Also, association between the level of urinary parabens with socio-demographic and lifestyle variables were investigated.

RESULTS

Detection frequencies of MP, EP, PP, and BP were 98.9, 91, 94.3, and 88.2%, and their median urinary concentrations were 69.06, 9.10, 12.4, and 9.87 µg/l, respectively. Urinary parabens were higher in females, and the difference in the concentration of MP and PP was significant. A significantly positive correlation between MP and PP (r = 0.638) and a moderate to a weak correlation between other parabens were observed. There was a significantly negative weak correlation between age and MP, BP and PP. There was also a significant association between different age groups and MP, BP and PP as well as different BMI values and MP. The highest EDI value belonged to MP in the female group. Despite being lower than the acceptable daily intake (ADI), its value was higher than that reported in other countries (except the US).

CONCLUSIONS

Our findings indicated that Iranians are widely exposed to the parabens and the range of exposure was associated with socio-demographic factors. These results could serve as a basis for assessing the risk of exposure to parabens amongst Iranians.

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.

Combined approaches for evaluation of xenoestrogen neural toxicity and thyroid dysfunction: Screening of oxido-nitrosative markers, DNA fragmentation, and biogenic amine degradation

Anthropogenic chemicals such as parabens and triclosan are used in personal care products. Due to their ability to decrease or prevent bacterial contamination and act as preservatives, these chemicals are used in cosmetic manufacturing processes to increase the shelf life of products. In this study, we assessed the side effects of environmental estrogens (such as the xenoestrogen butylparaben and the antimicrobial agent and preservative triclosan) on thyroid function, brain monoamine levels, and DNA aberration. Forty-two male albino rats were divided into seven groups with six members each: the first group served as control; the second and the third groups were treated with butylparaben 10 and 50 mg/kg body weight, respectively; the fourth and fifth groups were treated with triclosan 10 and 50 mg/kg body weight, respectively; and the sixth and seventh groups were treated with butylparaben plus triclosan 10 and 50 mg/kg body weight, respectively. After 60 days, blood samples were collected and brain specimens were divided into striatum, midbrain, cortex, and thalamus. Thyroid function and levels of monoamines and monoamine metabolites were determined for each brain area. Comet assay was used for brain tissue analysis. The results showed that butylparaben and triclosan and their combinations induced hypothyroidism and disrupted monoamine levels, leading to a decrease in catecholamine and serotonin levels, and accelerated production of 5-hydroxyindoleacetic acid. The obtained data indicate that anthropogenic chemicals such as butylparaben and triclosan have harmful effects on thyroid and brain function and accelerate cell destruction and mutation, as evidenced by single-stranded DNA breaks in the comet assay.