Maternal exposure to triclosan impairs thyroid homeostasis and female pubertal development in Wistar rat offspring

Association of prenatal exposure to phthalates and synthetic phenols with pubertal development in three European cohorts

BACKGROUND

There is limited epidemiological evidence on the association of prenatal exposure to phthalates and synthetic phenols with altered pubertal timing.

OBJECTIVE

To examine the association of prenatal exposure to phthalates, bisphenol A (BPA), parabens, benzophenone 3 (BP-3), and triclosan (TCS) with pubertal development in girls and boys from three European cohorts.

METHODS

Urinary metabolites of six different phthalate diesters (DEP, DiBP, DnBP, BBzP, DEHP, and DiNP), BPA, methyl- (MePB), ethyl- (EtPB), propyl- (PrPB), and butyl-paraben (BuPB), BP-3, and TCS were quantified in one or two (1st and 3rd trimester) urine samples collected during pregnancy (1999-2008) from mothers in three birth cohorts: INMA (Spain), EDEN (France), and MoBa (Norway). Pubertal development of their children was assessed at a single visit at age 7-12 years (579 girls, 644 boys) using the parent-reported Pubertal Development Scale (PDS). Mixed-effect Poisson and g-computation and Bayesian Kernel Machine Regression (BKMR) were employed to examine associations of individual and combined prenatal chemical exposure, respectively, with the probability of overall pubertal onset, adrenarche, and gonadarche (stage 2+) in girls and boys. Effect modification by child body mass index (BMI) was also assessed.

RESULTS

Maternal concentrations of the molar sum of DEHP and of DiNP metabolites were associated with a slightly higher probability of having started puberty in boys (relative risk, RR [95% CI] = 1.13 [0.98-1.30] and 1.20 [1.06-1.34], respectively, for a two-fold increase in concentrations), with a stronger association for DiNP in boys with overweight or obesity. In contrast, BPA, BuPB, EtPB, and PrPB were associated with a lower probability of pubertal onset, adrenarche, and/or gonadarche in all boys (e.g. overall puberty, BPA: RR [95% CI] = 0.93 [0.85-1.01] and BuPB: 0.95 [0.90-1.00], respectively), and the association with BPA was stronger in boys with underweight/normal weight. In girls, MEHP and BPA were associated with delayed gonadarche in those with underweight/normal weight (RR [95% CI] = 0.86 [0.77-0.95] and 0.90 [0.84-0.97], respectively). Most of these associations were trimester specific. However, the chemical mixture was not associated with any pubertal outcome in boys or girls.

CONCLUSIONS

Prenatal exposure to certain phthalates and synthetic phenols such as BPA may impact the pubertal development of boys, and weight status may modify this effect. BPA may also alter the pubertal development of girls.

Effects of pharmaceutical and personal care products on pubertal development: Evidence from human and animal studies

Pharmaceutical and personal care products (PPCPs) include a wide range of drugs, personal care products and household chemicals that are produced and used in significant quantities. The safety of PPCPs has become a growing concern in recent decades due to their ubiquitous presence in the environment and potential risks to human health. PPCPs have been detected in various human biological samples, including those from children and adolescents, at concentrations ranging from several ng/L to several thousand μg/L. Epidemiological studies have shown associations between exposure to PPCPs and changes in the timing of puberty in children and adolescents. Animal studies have shown that exposure to PPCPs results in advanced or delayed pubertal onset. Mechanisms by which PPCPs regulate pubertal development include alteration of the hypothalamic kisspeptin and GnRH networks, disruption of steroid hormones, and modulation of metabolic function and epigenetics. Gaps in knowledge and further research needs include the assessment of environmental exposure to pharmaceuticals in children and adolescents, low-dose and long-term effects of exposure to PPCPs, and the modes of action of PPCPs on pubertal development. In summary, this comprehensive review examines the potential effects of exposure to PPCPs on pubertal development based on evidence from human and animal studies.

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.

Quality and safety of South African hand sanitisers during the COVID-19 pandemic

Health agencies recommend using hand sanitisers as protection against the coronavirus. Thus far, the emphasis on hand sanitiser studies is limited to an analysis of disinfectant content only. This study aims to provide an extended analysis of 60 off-the-shelf alcohol-based hand sanitisers by using gas chromatography to report on alcohol content and the presence of impurities, a recombinant yeast estrogen screen to assess estrogenic activity, and an investigation into labelling compliance with the South African National Standard. Fifty hand sanitisers had an alcohol content of ≥60% v/v alcohol; however, most contained skin irritants and substances that could harm human and environmental health. Estrogenic activity was detected in 29 hand sanitisers and none of the products complied with all the labelling requirements. Since off-the-shelf hand sanitisers in South Africa are not regulated and monitored, evidence-based public awareness programmes on hand sanitiser quality and safety should become a priority.

Effects of chronic triclosan exposure on nephrotoxicity and gut microbiota dysbiosis in adult mice

Triclosan (TCS), a broad-spectrum, lipophilic, and antibacterial agent, has been commonly used in cosmetics, medical devices, and household products. The toxicity of TCS has recently become a research hotspot. Emerging evidence has shown that TCS can easily migrate to humans and animals and cause adverse effects on various target organs. However, the effects of TCS exposure on nephrotoxicity and underlying mechanisms remain unknown. The aim of the present study was to explore TCS-induced nephrotoxicity. Therefore, we establish a mouse model based on adult male mice to explore the effects of 10-week TCS exposure (50 mg/kg) on kidney. After mice were sacrificed, their blood, feces, and renal tissues were harvested for further analysis. We found that TCS treatment dramatically caused kidney structural damage, and increased blood urea nitrogen (BUN) and creatinine (Cr) expression levels, which indicated renal dysfunction. In addition, TCS exposure increased the malondialdehyde (MDA) and decreased superoxide dismutase (SOD) and total cholesterol (TCHO) expression levels, which indicated oxidative stress and lipid metabolism changes. The RNA sequencing (RNA-seq) of kidney tissue identified 221 differentially expressed genes (DEGs) enriched in 50 pathways, including drug metabolism-other enzymes, oxidative phosphorylation, glutathione metabolism, and inflammatory mediator regulation of TRP channels signaling pathways. The full-length 16S rRNA gene sequencing results showed that TCS exposure altered the community of gut microbiota, which was closely related to renal function damage. The above findings provide new insights into the mechanism of TCS-induced nephrotoxicity.

Prevalence of pharmaceuticals and personal care products, microplastics and co-infecting microbes in the post-COVID-19 era and its implications on antimicrobial resistance and potential endocrine disruptive effects

The COVID-19 (coronavirus disease 2019) pandemic's steady condition coupled with predominance of emerging contaminants in the environment and its synergistic implications in recent times has stoked interest in combating medical emergencies in this dynamic environment. In this context, high concentrations of pharmaceutical and personal care products (PPCPs), microplastics (MPs), antimicrobial resistance (AMR), and soaring coinfecting microbes, tied with potential endocrine disruptive (ED) are critical environmental concerns that requires a detailed documentation and analysis. During the pandemic, the identification, enumeration, and assessment of potential hazards of PPCPs and MPs and (used as anti-COVID-19 agents/applications) in aquatic habitats have been attempted globally. Albeit receding threats in the magnitude of COVID-19 infections, both these pollutants have still posed serious consequences to aquatic ecosystems and the very health and hygiene of the population in the vicinity. The surge in the contaminants post-COVID also renders them to be potent vectors to harbor and amplify AMR. Pertinently, the present work attempts to critically review such instances to understand the underlying mechanism, interactions swaying the current health of our environment during this post-COVID-19 era. During this juncture, although prevention of diseases, patient care, and self-hygiene have taken precedence, nevertheless antimicrobial stewardship (AMS) efforts have been overlooked. Unnecessary usage of PPCPs and plastics during the pandemic has resulted in increased emerging contaminants (i.e., active pharmaceutical ingredients and MPs) in various environmental matrices. It was also noticed that among COVID-19 patients, while the bacterial co-infection prevalence was 0.2-51%, the fungi, viral, protozoan and helminth were 0.3-49, 1-22, 2-15, 0.4-15% respectively, rendering them resistant to residual PPCPs. There are inevitable chances of ED effects from PPCPs and MPs applied previously, that could pose far-reaching health concerns. Furthermore, clinical and other experimental evidence for many newer compounds is very scarce and demands further research. Pro-active measures targeting effective waste management, evolved environmental policies aiding strict regulatory measures, and scientific research would be crucial in minimizing the impact and creating better preparedness towards such events among the masses fostering sustainability.

Extended exposure to tetrabromobisphenol A-bis(2,3-dibromopropyl ether) leads to subfertility in male mice at the late reproductive age

Tetrabromobisphenol A-bis(2,3-dibromopropyl ether) (TBBPA-BDBPE), a commonly used brominated flame retardant as a decabromodiphenyl ether substitute, has been detected in various environmental compartments, but its health hazards remain largely unknown. Our recent study showed that low-dose exposure of male mice to TBBPA-BDBPE from postnatal day (PND) 0 to 56 caused remarkable damage to the microtubule skeleton in Sertoli cells and the blood-testis barrier (BTB) but exerted little effect on conventional reproductive endpoints in adulthood. To investigate whether TBBPA-BDBPE may cause severe reproductive impairments at late reproductive age, here, we extended exposure of historically administrated male mice to 8-month age and allowed them to mate with non-treated females for the evaluation of fertility, followed by a general examination for the reproductive system. As expected, we found that 8-month exposure to 50 μg/kg/d as well as 1000 μg/kg/d TBBPA-BDBPE caused severe damage to the reproductive system, including reduced sperm counts, increased sperm abnormality, histological alterations of testes. Moreover, microtubule damage and BTB-related impairment were still observed following 8-month exposure. Noticeably, high-dose TBBPA-BDBPE-treated mice had fewer offspring with a female-biased sex ratio. All results show that long-term exposure to TBBPA-BDBPE caused severe reproductive impairment, including poor fertility at late reproductive age. It is therefore concluded that slight testicular injuries in early life can contribute to reproductive impairment at late reproductive age, highlighting that alterations in certain non-conventional endpoints should be noticed as well as conventional endpoints in future reproductive toxicity studies.

Prenatal triclosan exposure impairs mammalian lung branching morphogenesis through activating Bmp4 signaling

Triclosan (TCS) is a commonly used antibacterial agent present in personal care and household products. Recently, there have been increasing concerns about the association between children's health and TCS exposure during gestation, but the toxicological effects of TCS exposure on embryonic lung development remain undetermined. In this study, through using an ex vivo lung explant culture system, we found that prenatal exposure to TCS resulted in impaired lung branching morphogenesis and altered proximal-distal airway patterning. These TCS-induced dysplasias are accompanied by significantly reduced proliferation and increased apoptosis within the developing lung, as a consequence of activated Bmp4 signaling. Inhibition of Bmp4 signaling by Noggin partially rescues the lung branching morphogenesis and cellular defects in TCS-exposed lung explants. In addition, we provided in vivo evidence that administration of TCS during gestation leads to compromised branching formation and enlarged airspace in the lung of offspring. Thus, this study provides novel toxicological information on TCS and indicated a strong/possible association between TCS exposure during pregnancy and lung dysplasia in offspring.

Ototoxicity of Triclosan: A Rat Model Study

OBJECTIVE

Triclosan is utilized as an antibacterial factor in many industrial products. Although there are many toxic features of triclosan in the literature, there is no study on the effect of triclosan on hearing. The purpose of this study is to determine the effect of triclosan on hearing in rats.

METHODS

In this prospective, experimental animal study, 40 healthy Sprague-Dawley rats with normal response to the distortion-product otoacoustic emission (DPOAE) measurements were divided into four groups. Group 1, as the control group, was given only corn oil, group 2 was given 5 mg/kg triclosan dissolved in corn oil, group 3 was given 10 mg/kg triclosan dissolved in corn oil, and group 4 was given 100 mg/kg triclosan dissolved in corn oil; triclosan and corn oil were administered by oral gavage to all groups.

RESULTS

 In our study, low-dose triclosan did not cause hearing loss, but hearing loss was observed in the group that was given high-dose triclosan (100 mg/kg).

CONCLUSION

These findings suggest that triclosan causes hearing loss in rats. This issue should be investigated further to avoid triclosan ototoxicity in humans.

Urinary Phenols in Early to Midpregnancy and Risk of Gestational Diabetes Mellitus: A Longitudinal Study in a Multiracial Cohort

Environmental phenols are ubiquitous endocrine disruptors and putatively diabetogenic. However, data during pregnancy are scant. We investigated the prospective associations between pregnancy phenol concentrations and gestational diabetes mellitus (GDM) risk. In a nested matched case-control study of 111 individuals with GDM and 222 individuals without GDM within the prospective PETALS cohort, urinary bisphenol A (BPA), BPA substitutes (bisphenol F and bisphenol S [BPS]), benzophenone-3, and triclosan were quantified during the first and second trimesters. Cumulative concentrations across the two times were calculated using the area under the curve (AUC). Multivariable conditional logistic regression examined the association of individual phenols with GDM risk. We conducted mixture analysis using Bayesian kernel machine regression. We a priori examined effect modification by Asian/Pacific Islander (A/PI) race/ethnicity resulting from the case-control matching and highest GDM prevalence among A/PIs. Overall, first-trimester urinary BPS was positively associated with increased risk of GDM (adjusted odds ratio comparing highest vs. lowest tertile [aORT3 vs. T1] 2.12 [95% CI 1.00-4.50]). We identified associations among non-A/Ps, who had higher phenol concentrations than A/PIs. Among non-A/PIs, first-trimester BPA, BPS, and triclosan were positively associated with GDM risk (aORT3 vs. T1 2.91 [95% CI 1.05-8.02], 4.60 [1.55-13.70], and 2.88 [1.11-7.45], respectively). Triclosan in the second trimester and AUC were positively associated with GDM risk among non-A/PIs (P < 0.05). In mixture analysis, triclosan was significantly associated with GDM risk. Urinary BPS among all and BPA, BPS, and triclosan among non-A/PIs were associated with GDM risk. Pregnant individuals should be aware of these phenols' potential adverse health effects.

Feasibility study for a downsized comparative thyroid assay with measurement of brain thyroid hormones and histopathology in rats: Case study with 6-propylthiouracil and sodium phenobarbital at high dose

Concern has been raised that thyroid hormone disruptors (THDs) may potentially interfere with the developing brain, but effects of mild suppression of maternal THs by environmental contaminants on neonatal brain development are not fully understood. The comparative thyroid assay (CTA) is a screening test for offspring THDs, but it requires several animals and is criticized that reliance on serum THs alone as predictive markers of brain malfunction is inadequate. To verify feasibility of the downsized CTA but additional examination of brain THs levels and histopathology, we commenced internal-validation studies. This paper presents the data of the study where 6-propylthiouracil (6-PTU, 10 ppm) and sodium phenobarbital (NaPB, 1000 ppm) were dosed by feeding from gestational days (GD)6-20, and from GD6 to lactation day 21. The modified CTA detected 6-PTU-induced severe (>70%) suppression of serum THs in dams, with >50% suppressed serum/brain TH levels in offspring and brain heterotopia in postnatal day 21 pups. The modified CTA also detected NaPB-induced mild (<35%) suppression of serum THs in dams, with mild (<35%) reduction of serum/brain TH levels in fetuses but not in pups. These findings suggest that the modified CTA may have a potential as a screening test for offspring THDs.

Effect of triclosan exposure on ovarian hormones, trace elements and growth in female rats

Triclosan (TCS) is an antibacterial compound used mainly in personal care products. Its widespread use for decades has made it one of the most widely detected compounds in environmental matrices and in biological fluids. Although it has been shown to be an endocrine disruptor in rats and aquatic species, its safe use by humans is unclear. The aim of the present study was to evaluate the effects of exposure to TCS in female rats. To this end, 14 rats were divided into two groups and fed daily as follows: the control group with sesame oil and the TCS group at a dose of 50 mg/kg/day for 28 days. Any signs of toxicity in the rats were observed daily, and the weight and phase of the estrous cycle were recorded. At the end, the rats were decapitated, the serum and ovaries were collected. The levels of testosterone and progesterone in serum were determined by immunoassay and mass spectrometry. Estradiol (in serum) and kisspeptin-10 (in serum and ovary) were measured only by immunoassays. Trace elements were determined by inductively coupled plasma-mass spectrometry (ICP-MS). The weight gain study of the rats showed a significant decrease by exposure to TCS, while the estrous cycle was not significantly affected compared to the control. The optimized methods based on mass spectrometry showed a significant decrease in the levels of progesterone and testosterone due to exposure to TCS. In addition, elements determined by ICP-MS in rat serum showed significant changes in calcium, lithium and aluminum due to TCS treatment. Finally, the kisspeptin-10 levels did not show a negative effect due to the treatment by TCS. The results suggest that medium-term exposure to TCS did not significantly alter estrous cyclicity but caused alterations in growth, sex hormone levels and some elements in the rat serum.

The Effect of Early Life Exposure to Triclosan on Thyroid Follicles and Hormone Levels in Zebrafish

Triclosan (TCS) is an antimicrobial chemical widely used in personal care products. Most of the TCS component is discharged and enters the aquatic ecosystem after usage. TCS has a similar structure as thyroid hormones that are synthesized by thyroid follicular epithelial cells, thus TCS has a potential endocrine disrupting effect. It is still not clear how the different levels of the environmental TCS would affect early development in vivo. This study examines the effects of TCS on thyroid hormone secretion and the early development of zebrafish. The fertilized zebrafish eggs were exposed to TCS at 0 (control), 3, 30, 100, 300, and 900 ng/mL, and the hatching rate and the larvae mortality were inspected within the first 14 days. The total triiodothyronine (TT₃), total thyroxine (TT₄), free triiodothyronine (FT₃), and free thyroxine (FT₄) were measured at 7, 14, and 120 days post-fertilization (dpf). The histopathological examinations of thyroid follicles were conducted at 120 dpf. TCS exposure at 30-300 ng/mL reduced the hatching rate of larvae to 34.5% to 28.2 % in the first 48 hours and 93.8 .7 % to 86.8 % at 72 h. Extremely high TCS exposure (900 ng/mL) strongly inhibited the hatching rate, and all the larvae died within 1 day. Exposure to TCS from 3 to 300 ng/mL reduced the thyroid hormones production. The mean TT₃ and FT₃ levels of zebrafish decreased in 300 ng/mL TCS at 14 dpf (300 ng/mL TCS vs. control : TT₃ , 0.19 ± 0.08 vs. 0.39 ± 0.06; FT₃, 19.21 ± 3.13 vs. 28.53 ± 1.98 pg/mg), and the FT₄ decreased at 120 dpf ( 0.09 ± 0.04 vs. 0.20 ± 0.14 pg/mg). At 120 dpf , in the 300 ng/mL TCS exposure group, the nuclear area and the height of thyroid follicular epithelial cells became greater, and the follicle cell layer got thicker. This happened along with follicle hyperplasia, nuclear hypertrophy, and angiogenesis in the thyroid. Our study demonstrated that early life exposure to high TCS levels reduces the rate and speed of embryos hatching, and induces the histopathological change of thyroid follicle, and decreases the TT₃, FT₃, and FT₄ production in zebrafish.

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.

In vitro and in vivo estrogenic activity of triclosan

Triclosan (TCS) is an antibacterial and antifungal agent used in many consumer products and exhibits a chemical structure similar to non-steroidal estrogen, which is known to induce endocrine disruption. Triclosan has been found in human plasma, urine, and breast milk, and the safety of TCS-containing products has been disputed. Although studies attempted to determine the estrogenic activity of TCS, no clear results have emerged. The aim of the present study was to examine estrogenic activity of TCS using an in vitro E-screen assay and an in vivo uterotrophic assay. The in vitro E-screen assay demonstrated that TCS significantly enhanced proliferation of MCF-7 breast cancer cells, although not in a concentration-dependent manner. The in vivo uterotrophic results showed no significant change in the weight of uteri obtained from TCS-administered Sprague-Dawley rats. Further, to understand the estrogenic activity attributed to TCS at the molecular level, gene-expression profiling of uterus samples was performed from both TCS- or estrogen-treated rats and the genes and cellular processes affected by TCS or estrogen were compared. Data demonstrated that both the genes and cellular processes affected by TCS or estrogen were significantly similar, indicating the possibility that TCS-mediated estrogenic activity occurred at the global transcriptome level. In conclusion, in vitro and gene-profiling results suggested that TCS exhibited estrogenic activity.

Exposure to Phenols, Phthalates, and Parabens and Development of Metabolic Syndrome Among Mexican Women in Midlife

Background: Evidence suggests exposure to endocrine-disrupting chemicals (EDCs) can influence Metabolic Syndrome (MetS) risk in adults, but it is unclear if EDCs impact women during midlife. We examined if EDCs measured in adult women were predictive of MetS and its components 9 years later. Methods: We measured urinary phthalate metabolites, phenols, and parabens collected in 2008 among 73 females from the ELEMENT study. MetS and its components (Abdominal Obesity, Hypertriglyceridemia, Cholesterolemia, Hypertension, and Hyperglycemia) were assessed in 2017. We regressed log-transformed EDC concentrations on MetS and MetS components using logistic regression, adjusting for age and physical activity. Results: At follow-up, the mean (SD) age was 46.6 (6.3) years; the prevalence of MetS was 34.3%. Sum of dibutyl phthalate metabolites (ΣDBP), monobenzyl phthalate (MBzP), and monoethyl phthalate (MEP) were associated with an increased odds of hypertriglyceridemia. 2,5-dichlorophenol (2,5 DCP) and 2,4-dichlorophenol (2,4 DCP) were associated with increased odds of hypertriglyceridemia. The odds of hypertension were 4.18 (95% CI: 0.98, 17.7, p < 0.10) and 3.77 (95% CI: 0.76, 18.62, p < 0.10) times higher for every IQR increase in MCOP and propyl paraben, respectively. The odds of hyperglycemia were 0.46 (95% CI: 0.18, 1.17 p < 0.10) times lower for every IQR increase in the sum of di-2-ethylhexyl phthalate metabolites (ΣDEHP), and the odds of abdominal obesity were 0.70 (95% CI: 0.40, 1.21, p < 0.10) lower for every IQR increase in the concentration of triclosan. Conclusion: We found EDCs measured in 2008 were marginally predictive of hypertriglyceridemia and hypertension 9 years later. Results suggest that lower exposure to certain toxicants was related to lower markers of metabolic risk among midlife women.

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.

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.

Association between phenols exposure and earlier puberty in children: A systematic review and meta-analysis

OBJECTIVE

To identify the association between phenolic chemicals and the risk of earlier puberty based on the available evidence by systematic review and meta-analysis.

METHODS

Databases PubMed, Web of Science, and Cochrane Library were searched and retrieved appropriate journal articles on the association between phenols exposure and earlier puberty in children published before February 14, 2020. Stata software version 12.0 and Excel were used for statistical analysis.

RESULTS

Nine studies were included in the meta-analysis with total subjects of 4737. All the subjects included in our studies were girls. The pooled estimate has shown the association between 2, 5- dichrolophenol exposure, and earlier puberty in children with effect size (ES) 1.13 (95% CI: 1.06, 1.20). Exposed to other types of phenolic chemicals such as bisphenol A, Triclosan, Benzophenone-3 were not statistically significant associated with the risk of earlier puberty in children with the overall pooled estimates of ES of 1.09 (95%CI: 0.88, 1.35), ES 1.05(95% CI: 0.96, 1.15), and ES 0.98 (95% CI: 0.88, 1.10) respectively.

CONCLUSION

Our results portray that phenols particularly 2, 5- dichlorophenol exposure might be associated with the risk of earlier puberty in children. Also, caution should be taken to other type of phenolic chemicals since in subgroup analysis some individual studies have shown a positive relationship between bisphenol A, Triclosan and Benzophenone-3 exposures, and the risk of earlier puberty in children. Future cohort studies should be conducted with more sample sizes to determine the relationship between 2, 5- dichlorophenol, and the risk of earlier puberty in children of all gender.

Perinatal Exposure to Triclosan Results in Abnormal Brain Development and Behavior in Mice

Triclosan (TCS) is one of the most common endocrine-disrupting chemicals (EDCs) present in household and personal wash products. Recently, concerns have been raised about the association between abnormal behavior in children and exposure to EDC during gestation. We hypothesized that exposure to TCS during gestation could affect brain development. Cortical neurons of mice were exposed in vitro to TCS. In addition, we examined in vivo whether maternal TCS administration can affect neurobehavioral development in the offspring generation. We determined that TCS can impair dendrite and axon growth by reducing average length and numbers of axons and dendrites. Additionally, TCS inhibited the proliferation of and promoted apoptosis in neuronal progenitor cells. Detailed behavioral analyses showed impaired acquisition of spatial learning and reference memory in offspring derived from dams exposed to TCS. The TCS-treated groups also showed cognition dysfunction and impairments in sociability and social novelty preference. Furthermore, TCS-treated groups exhibited increased anxiety-like behavior, but there was no significant change in depression-like behaviors. In addition, TCS-treated groups exhibited deficits in nesting behavior. Taken together, our results indicate that perinatal exposure to TCS induces neurodevelopment disorder, resulting in abnormal social behaviors, cognitive impairment, and deficits in spatial learning and memory in offspring.

Perinatal Triclosan exposure in the rat induces long-term disturbances in metabolism and gut microbiota in adulthood and old age

Triclosan (TCS), as a widely used antimicrobial compound, is commonly detected in pregnant women and newborns indicating exposure risk during early development. However, whether perinatal TCS exposure has long-term effects on the host microbiome which further contributes to metabolic disorder is still unclear. The long-term effects of perinatal TCS exposure on gut microbiota and liver metabolism in adulthood and old age were investigated. Rats were given 0, 10 or 50 mg TCS/kg body weight per day, administered daily by gavage from gestation day 0 until lactation day 21. RNA-sequencing and 16 S rDNA amplicon sequencing analysis were performed to explore the potential mechanisms. Increased blood glucose and serum HDL-C were observed at 10 mg/kg/day in old rats and at 50 mg/kg/day in both adult and old rats. Serum leptin were increased at two doses in old rats. Serum TG and LDL-C were increased at two doses in both adult and old rats. Hepatic glycogen were decreased at 50 mg/kg/day in adult rats and at two doses in old rats. Increased hepatic TG were observed at two doses in old rats. Hepatic RNA-sequencing revealed that more differentially expressed genes were found at 50 mg/kg/day in both adult and old rats. More up-regulated genes in pathways of carbohydrate and lipid metabolism were observed in old rats at 50 mg/kg/day. Diversity reduction and compositional alteration were found in gut microbiota at 50 mg/kg/day in adult rats and at two doses in old rats. These effects lasted for a long time even without TCS exposure and accumulated over time inducing metabolic disorder in old rat offspring. TCS exposure during early life causes disturbances in metabolism and gut microbiota which last a lifetime and accumulated over time at 50 mg/kg/day. Further research is needed to investigate the effects of early life TCS exposure on metabolism and gut microbiota in humans.

Characterization of covalent protein modification by triclosan in vivo and in vitro via three-dimensional liquid chromatography-mass spectrometry: New insight into its adverse effects

Triclosan (TCS), an antimicrobial agent widely used in personal care products and ubiquitously exists in environment, has drawn increasing concern due to its potential to exert multiple adverse effects, ranging from endocrine disruption to carcinogenesis. However, the mechanism of these adverse effects is still not fully elucidated. More and more studies have shown that chemical reactive metabolites (RMs) covalently binding to proteins is a possible reason for these adverse effects, but there is still a lack of appropriate methods to predict or evaluate these adverse effects due to the extremely low abundance of the modified proteins in complex biological samples. In this study, we attempted to address this problem and investigate the possible mechanism of TCS adverse effects by a shotgun proteomics approach based on three-dimensional-liquid chromatography-mass spectrometry (3D-LC-MS). First, the in vitro incubation with model amino acids and protein in microsomes showed that TCS could react with cysteine residue of proteins through 3 types of RMs. Then, a 3D-LC-MS approach was developed to sensitively determine the low abundant modified proteins, which resulted in the identification of 45 TCS-modified proteins, including albumin, haptoglobin and NR1I2, in rats. STRING analysis indicated that these modified proteins mainly were involved in reproductive and development system, endocrine and immune system, and carcinogenesis, which were in accord with the main reported TCS-induced adverse effects and suggested that the covalent modification of TCS RMs for proteins might affect their activities and functions, thus inducing serious adverse effects. This study provided a new insight into the mechanism of TCS adverse effects and may serve as a valuable method to predict or evaluate adverse effects of ubiquitous chemicals.

Associations of Prenatal Exposure to Triclosan and Maternal Thyroid Hormone Levels: A Systematic Review and Meta-Analysis

OBJECTIVE

To quantitatively evaluate associations between exposure to triclosan during pregnancy and maternal thyroid hormone levels.

METHOD

The databases of PubMed, Embase, Web of Science and Cochrane Library were systematically searched to identify relevant studies on the relationship between prenatal exposure to triclosan and maternal levels of serum thyroid hormone published before October 22, 2019. Stata 12.0 was used to examine the heterogeneity among the eligible studies.

RESULTS

Seven studies involving a total of 4,136 participants were included. Overall, descriptive analysis provided no indication that exposure to TCS during pregnancy was related to either maternal FT4 levels (ES = 0.01, 95% CI: -0.03 to 0.05, P = 0.00) or TSH levels (ES = -0.03, 95% CI: -0.13 to 0.07, P = 0.412). Although the results were statistically insignificant, with the increase of urine TCS concentration, maternal FT4 levels exhibited a tendency to increase while TSH levels had a tendency to decrease during pregnancy.

CONCLUSION

The results indicated that exposure to triclosan during pregnancy has no significant influence on maternal levels of thyroid hormone. On account of the inconsistency of existing research designs and study locations, further studies and replication are necessary to confirm these findings.

An Insight into Ingredients of Toxicological Interest in Personal Care Products and A Small–Scale Sampling Survey of the Greek Market: Delineating a Potential Contamination Source for Water Resources

Wastewater is not a waste but a valuable resource that should be reused. Nevertheless, it should be devoid of physical, chemical, and microbiological parameters that can harm the consumer. Along with the multitude of possible pollutants found in wastewater treatment plants (WWTPs), emerging pollutants, such as Personal Care Products (PCPs), have arisen. The present research examines some of the main ingredients commonly found in PCPs, focusing on their toxicological profile on their occurrence in WWTPs influents and effluents worldwide and on their persistence and biodegradability. A small-scale market sampling of PCPs was performed in Athens, Greece, in June 2019, and their individual ingredients were recorded, coded according to their main activity, scanned for the presence of ingredients of important toxicological profile, and finally analyzed for the presence of other candidates of toxicological interest. Results show that some ingredients of concern (i.e., parabens and triclosan) are a decreasing trend. On the other hand, information on the presence of synthetic musks and perfume synthesis is scarce and encumbered by brand protection. Finally, UV filters are numerous, and they are used in various combinations, while other ingredients of toxicological interest are also present. Since the reclaimed water may well be used to cover irrigation needs in Greek areas with water deficiency or to enrich bodies of surface water, it is important to know what PCP ingredients are on the rise in the market, to monitor their presence in WWTPs influents and effluents and to extend research on their environmental fate and behavior.

Association of phthalates, parabens and phenols found in personal care products with pubertal timing in girls and boys

STUDY QUESTION

Are in-utero or peripubertal exposures to phthalates, parabens and other phenols found in personal care products associated with timing of pubertal onset in boys and girls?

SUMMARY ANSWER

We found some associations of altered pubertal timing in girls, but little evidence in boys.

WHAT IS KNOWN ALREADY

Certain chemicals in personal care and consumer products, including low molecular weight phthalates, parabens and phenols, or their precursors, are associated with altered pubertal timing in animal studies.

STUDY DESIGN, SIZE, DURATION

Data were from the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) longitudinal cohort study which followed 338 children in the Salinas Valley, California, from before birth to adolescence.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Pregnant women were enrolled in 1999-2000. Mothers were mostly Latina, living below the federal poverty threshold and without a high school diploma. We measured concentrations of three phthalate metabolites (monoethyl phthalate [MEP], mono-n-butyl phthalate and mono-isobutyl phthalate), methyl and propyl paraben and four other phenols (triclosan, benzophenone-3 and 2,4- and 2,5-dichlorophenol) in urine collected from mothers during pregnancy and from children at age 9. Pubertal timing was assessed among 179 girls and 159 boys every 9 months between ages 9 and 13 using clinical Tanner staging. Accelerated failure time models were used to obtain mean shifts of pubertal timing associated with concentrations of prenatal and peripubertal biomarkers.

MAIN RESULTS AND THE ROLE OF CHANCE

In girls, we observed earlier onset of pubic hair development with prenatal urinary MEP concentrations and earlier menarche with prenatal triclosan and 2,4-dichlorophenol concentrations. Regarding peripubertal biomarkers, we observed: earlier breast development, pubic hair development and menarche with methyl paraben; earlier menarche with propyl paraben; and later pubic hair development with 2,5-dichlorophenol. In boys, we observed no associations with prenatal urinary biomarker concentrations and only one association with peripubertal concentrations: earlier genital development with propyl paraben.

LIMITATIONS, REASONS FOR CAUTION

These chemicals are quickly metabolized and one to two urinary measurements per developmental point may not accurately reflect usual exposure. Associations of peripubertal measurements with parabens may reflect reverse causality: children going through puberty early may be more likely to use personal care products. The study population was limited to Latino children of low socioeconomic status living in a farmworker community and may not be widely generalizable.

WIDER IMPLICATIONS OF THE FINDINGS

This study contributes to a growing literature that suggests that exposure to certain endocrine disrupting chemicals may impact timing of puberty in children.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by the National Institute of Environmental Health Sciences and the US Environmental Protection Agency. The authors declare no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

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.

Bioaccumulation and risks of 24 personal care products in plasma of wild fish from the Yangtze River, China

We used a hybrid precipitation method to simultaneously extract and analyze 24 personal care products (PCPs), including 16 biocides, 4 synthetic musks, and 4 benzotriazoles, in the plasma of fish. The method's performance was validated for plasma samples with and without β-glucuronidase/aryl-sulfatase hydrolysis. The recoveries were in the range of 70-120% for most of the PCPs, except N,N-diethyl-3-methylbenzamide (DEET), clotrimazole (CTZ), miconazole and itraconazole at spiking concentration of 20 and 5 ng/mL. The quantification limits ranged between 0.89 and 17.9 ng/mL (hydrolyzed plasma) and 0.85-18.5 ng/mL (non-hydrolyzed plasma), except CTZ at 77.5 ng/mL and 76.3 ng/mL. Totally, 13 PCPs were detected in plasma samples of fish collected from the Yangtze River, with a maximum concentration of 58.4 ng/mL (galaxolide). Compounds with the phenol hydroxyl groups of parabens or triclosan in hydrolyzed plasma showed higher concentrations than those in unhydrolyzed plasma with the ratio of conjugation (glucuronides + sulfates) forms up to 86%. The median values for the logarithm of bioaccumulation factors were between 1.39 and 4.15, which were 2-3 orders of magnitude higher than the theoretical logarithm of bioconcentration factors. Using the fish plasma model, the effect ratios (effect concentration/measured plasma concentration ratios) of tonalide, galaxolide, benzotriazole, triclosan, and DEET reached 0.35, 4.15, 3.78, 7.52, and 9.24, respectively. These are recognized as priority chemicals for further risk assessment.

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.

Risk Assessment of Triclosan, a Cosmetic Preservative

Triclosan (TCS) is an antimicrobial compound used in consumer products. The purpose of current study was to examine toxicology and risk assessment of TCS based on available data. Acute toxicities of oral, transdermal and inhalation routes were low, and phototoxicity and neurotoxicity were not observed. Topical treatment of TCS to animal caused mild irritation. TCS did not induce reproductive and developmental toxicity in rodents. In addition, genotoxicity was not considered based on in vitro and in vivo tests of TCS. It is not classified as a carcinogen in international authorities such as International Agency for Research on Cancer (IARC). No-observed-adverse-effect level (NOAEL) was determined 12 mg/kg bw/day for TCS, based on haematoxicity and reduction of absolute and relative spleen weights in a 104-week oral toxicity study in rats. Percutaneous absorption rate was set as 14%, which was human skin absorption study reported by National Industrial Chemicals Notification and Assessment Scheme (NICNAS) (2009). The systemic exposure dosage (SED) of TCS has been derived by two scenarios depending on the cosmetics usage of Koreans. The first scenario is the combined use of representative cosmetics and oral care products. The second scenario is the combined use of rinse-off products of cleansing, deodorants, coloring products, and oral care products. SEDs have been calculated as 0.14337 mg/kg bw/day for the first scenario and 0.04733 mg/kg bw/day for the second scenario. As a result, margin of safety (MOS) for the first and second scenarios was estimated to 84 and 253.5, respectively. Based on these results, exposure of TCS contained in rinse-off products, deodorants, and coloring products would not pose a significant health risk when it is used up to 0.3%.

Skin safety and health prevention: an overview of chemicals in cosmetic products

INTRODUCTION

Cosmetic products contain a wide range of chemicals to which we are exposed every day. The aim of the study was to determine the presence of potential dangerous substances which can cause adverse health effects by examining product labels.

MATERIALS AND METHODS

A total of 283 products were collected from various shops in Lecce (Italy) and divided into 3 categories: rinse-off, leave-on and make-up. The label of every product was examined and a list including fragrances, preservatives and other chemicals of concern was created.

RESULTS

Fragrances were present in 52.3% of the examined products, mostly limonene (76.9%) and linalool (64.6%) but also citronellol (34.1%), geraniol (31.5%), coumarin (30%) and hexyl cinnamal (29.2%). Preservatives showed a rate of 60% and the most frequently identified were phenoxyethanol (48.7%), sodium benzoate (35.6%), potassium sorbate (22%), methylparaben (15.2%) and MI/MCI (9.9%). The other chemicals of concern were detected in 58% of products; included PEGs (62.3%), acrylate copolymer (34%), petrolatum (17.2%), polysorbates (14,8%), BHT (14.7%), ethylhextyl methoxycinnamate (13.6%), benzophenone-1 (3.7%), benzophenone-3 (4.9%), BHA (1.6%), cocamide DEA and toluene (1.2%).

CONCLUSIONS

The use of many of these substances is allowed within certain limits, due to their toxicity at higher concentrations. Other important aspects should be considered as, for instance, the possibility of long-term effects. On the other hand, other substances may induce several acute adverse side-effects, i.e. contact dermatitis and allergic reactions. For these reasons, an enhancement of the criteria used for cosmetics formulation is required since many chemicals used singularly or combined are potentially unsafe.

Early-life exposure to endocrine disrupting chemicals associates with childhood obesity

Increasing prevalence of childhood obesity poses threats to the global health burden. Because this rising prevalence cannot be fully explained by traditional risk factors such as unhealthy diet and physical inactivity, early-life exposure to endocrine disrupting chemicals (EDCs) is recognized as emerging novel risk factors for childhood obesity. EDCs can disrupt the hormone-mediated metabolic pathways, affect children's growth and mediate the development of childhood obesity. Many organic pollutants are recently classified to be EDCs. In this review, we summarized the epidemiological and laboratory evidence related to EDCs and childhood obesity, and discussed the possible mechanisms underpinning childhood obesity and early-life exposure to non-persistent organic pollutants (phthalates, bisphenol A, triclosan) and persistent organic pollutants (dichlorodiphenyltrichloroethane, polychlorinated biphenyls, polybrominated diphenyl ethers, per- and polyfluoroalkyl substances). Understanding the relationship between EDCs and childhood obesity helps to raise public awareness and formulate public health policy to protect the youth from exposure to the harmful effects of EDCs.

The association of repeated measurements of prenatal exposure to triclosan with fetal and early-childhood growth

BACKGROUND

Triclosan (TCS) is known to possess endocrine disrupting properties and metabolize rapidly in the human body. Human data concerning repeated measurements of TCS throughout pregnancy in relation to fetal and childhood growth are sparse.

OBJECTIVES

We investigated the associations between multiple measurements of maternal urinary concentrations of TCS during pregnancy and fetal and early-childhood growth.

METHODS

The study population included 850 mother-infant pairs who participated in a prenatal cohort established between 2014 and 2015 in Wuhan. Prenatal TCS exposure was measured in a complete series of urine samples collected at the first, second and third trimesters. General linear models and generalized estimating equation models were applied to evaluate the associations of the averaged maternal urinary concentrations of TCS over trimesters and trimester-specific urinary TCS with the z-scores of estimated fetal weight, head circumference, abdominal circumference, and femur length at 16, 24, and 31 gestational weeks, weight and length at birth, and weight and height at 0.5, 1, and 2 years of age.

RESULTS

In overall infants, we did not observe any significant association of the averaged maternal urinary concentrations of TCS over trimesters with ultrasound parameters and size at birth. However, a positive association of borderline statistical significance was found between averaged prenatal TCS exposure and the third-trimester estimated fetal weight z-score in girls in sex-stratified analyses (β = 0.054, 95% CI: -0.005, 0.113, p = 0.07). Moreover, averaged prenatal TCS exposure was positively associated with 2 year-old weight z-score among total infants (β = 0.046, 95% CI: 0.005, 0.087). After stratifying by sex, the same association was observed in girls with more prominent estimation (β = 0.062, 95% CI: 0.000, 0.124), whereas the association weakened and became not significant in boys (β = 0.033, 95% CI: -0.024, 0.089). TCS exposure at 1st and 2nd-trimester were positively associated with weight z-score at 2 years, in both overall and female infants.

CONCLUSIONS

Prenatal exposure to triclosan was associated with elevated third-trimester estimated fetal weight and 2 year-old weight z-score in girls, and the early and middle stage of pregnancy may be the windows of vulnerability. Apart from these findings, we did not find strong evidence for prenatal triclosan exposure in relation to fetal and early-childhood growth.

Exposure of pregnant mice to triclosan causes hyperphagic obesity of offspring via the hypermethylation of proopiomelanocortin promoter

Triclosan (TCS), as a broad spectrum antibacterial agent, is commonly utilized in personal care and household products. Maternal urinary TCS level has been associated with changes in birth weight of infants. We in the present study investigated whether exposure of mice to 8 mg/kg TCS from gestational day (GD) 6 to GD14 alters prenatal and postnatal growth and development, and metabolic phenotypes in male and female offspring (TCS-offspring). Compared with control offspring, body weight in postnatal day (PND) 1 male or female TCS-offspring was reduced, but body weight gain was faster within postnatal 5 days. PND30 and PND60 TCS-offspring showed overweight with increases in visceral fat and adipocyte size. PND60 TCS-offspring displayed delayed glucose clearance and insulin resistance. PND30 TCS-offspring showed an increase in food intake without the changes in the oxygen consumption and respiratory exchange ratio (RER). The expression levels of proopiomelanocortin (POMC), α-melanocyte-stimulating hormone (α-MSH) and single-minded 1 (SIM1) in hypothalamus arcuate nucleus (ARC) and paraventricular nucleus (PVN), respectively, were significantly reduced in PND30 TCS-offspring compared to controls. The hypermethylation of CpG sites at the POMC promoter was observed in PND30 TCS-offspring, while the concentration of serum leptin was elevated and the level of STAT3 phosphorylation in ARC had no significant difference from control. This study demonstrates that TCS exposure during early/mid-gestation through the hypermethylation of the POMC promoter reduces the expression of anorexigenic neuropeptides to cause the postnatal hyperphagic obesity, leading to metabolic syndrome in adulthood.

Associations of maternal exposure to triclosan, parabens, and other phenols with prenatal maternal and neonatal thyroid hormone levels

Environmental phenols and parabens are commonly used in personal care products and other consumer products and human exposure to these chemicals is widespread. Although human and animal studies suggest an association between exposure to phenols and parabens and thyroid hormone levels, few studies have investigated the association of in utero exposure to these chemicals and thyroid hormones in pregnant women and their neonates. We measured four environmental phenols (triclosan, benzophenone-3, and 2,4- and 2,5-dichlorophenol), and three parabens (methyl-, propyl-, and butyl paraben) in urine collected from mothers at two time points during pregnancy as part of the CHAMACOS (Center for the Health Assessment of Mothers and Children of Salinas) study. We measured free thyroxine (T4), total T4, and thyroid-stimulating hormone (TSH) in serum of the pregnant women (N = 454) and TSH in their neonates (N = 365). We examined potential confounding by a large number of additional chemical exposures and used Bayesian Model Averaging (BMA) to select the most influential chemicals to include in regression models. We observed negative associations of prenatal urinary concentrations of propyl paraben and maternal TSH (β for two-fold increase = -3.26%, 95% CI: -5.55, -0.90) and negative associations of 2,4-dichlorophenol and maternal free T4 (β for two-fold increase = -0.05, 95% CI: -0.08, -0.02), after controlling for other chemical exposures. We observed negative associations of triclosan with maternal total T4 after controlling for demographic variables, but this association became non-significant after controlling for other chemicals (β for two-fold increase = -0.05, 95% CI: -0.11, 0.00). We found evidence that environmental phenols and parabens are associated with lower TSH and free T4 in pregnant women after controlling for related chemical exposures.

Associations between maternal phenol and paraben urinary biomarkers and maternal hormones during pregnancy: A repeated measures study

BACKGROUND

A number of phenols and parabens are added to consumer products for a variety of functions, and have been found at detectable levels in the majority of the U.S.

POPULATION

Among other functions, thyroid hormones are essential in fetal neurodevelopment, and could be impacted by the endocrine disrupting effects of phenols and parabens. The present study investigated the association between ten maternal urinary phenol and paraben biomarkers (bisphenol S, triclosan, triclocarban, benzophenone-3, 2,4-dichlorophenol, 2,5-dichlorophenol, and ethyl, butyl, methyl and propyl paraben) and four plasma thyroid hormones in 439 pregnant women in a case-control sample nested within a cohort study based in Boston, MA.

METHODS

Urine and blood samples were collected from up to four visits during pregnancy (median weeks of gestation at each visit: Visit 1: 9.64, Visit 2: 17.9, Visit 3: 26.0, Visit 4: 35.1). Linear mixed models were constructed to take into account the repeated measures jointly, followed by multivariate linear regression models stratified by gestational age to explore potential windows of susceptibility.

RESULTS

We observed decreased total triiodothyronine (T3) in relation to an IQR increase in benzophenone-3 (percent change [%Δ] = -2.07; 95% confidence interval [CI] = -4.16, 0.01), butyl paraben (%Δ = -2.76; 95% CI = -5.25, -0.26) and triclosan (%Δ = -2.53; 95% CI = -4.75, -0.30), and triclocarban at levels above the LOD (%Δ = -5.71; 95% CI = -10.45, -0.97). A 2.41% increase in T3 was associated with an IQR increase in methyl paraben (95% CI = 0.58, 4.24). We also detected a negative association between free thyroxine (FT4) and propyl paraben (%Δ = -3.14; 95% CI = -6.12, -0.06), and a suggestive positive association between total thyroxine (T4) and methyl paraben (%Δ = 1.19; 95% CI = -0.10, 2.47). Gestational age-specific multivariate regression analyses showed that the magnitude and direction of some of the observed associations were dependent on the timing of exposure.

CONCLUSION

Certain phenols and parabens were associated with altered thyroid hormone levels during pregnancy, and the timing of exposure influenced the association between phenol and paraben, and hormone concentrations. These changes may contribute to downstream maternal and fetal health outcomes. Additional research is required to replicate the associations, and determine the potential biological mechanisms underlying the observed associations.

Thyroid-disrupting chemicals and brain development: an update

This review covers recent findings on the main categories of thyroid hormone-disrupting chemicals and their effects on brain development. We draw mostly on epidemiological and experimental data published in the last decade. For each chemical class considered, we deal with not only the thyroid hormone-disrupting effects but also briefly mention the main mechanisms by which the same chemicals could modify estrogen and/or androgen signalling, thereby exacerbating adverse effects on endocrine-dependent developmental programmes. Further, we emphasize recent data showing how maternal thyroid hormone signalling during early pregnancy affects not only offspring IQ, but also neurodevelopmental disease risk. These recent findings add to established knowledge on the crucial importance of iodine and thyroid hormone for optimal brain development. We propose that prenatal exposure to mixtures of thyroid hormone-disrupting chemicals provides a plausible biological mechanism contributing to current increases in the incidence of neurodevelopmental disease and IQ loss.

Evaluation of subchronic exposure to triclosan on hepatorenal and reproductive toxicities in prepubertal male rats

Triclosan (TCS), a common antimicrobial ingredient, is present in many consumer products, including soaps, shampoos, and toothpaste. Owing to its widespread use, potential adverse effects on animals and humans may arise from lifetime exposure, but data on chronic prepubertal exposure of TCS are still lacking. The aim of the present study was to investigate the influence of subchronic TCS exposure (0.25, 25, 250, or 750 mg/kg) on target organ toxicity in prepubertal male rats. After daily administration of TCS to rats by oral gavage for 60 d, a significant reduction in body weight and relative weights of liver, kidneys, testes, and adrenal glands was observed in the 750-mg/kg (high dose) group. Serum alanine aminotransferase and aspartate aminotransferase activities as well as levels of blood urea nitrogen, and creatinine were significantly increased at 750 mg/kg TCS. Further, TCS (750 mg/kg) elevated the protein expressions of hepatic CYP2B1, RXR/PPAR, and levels of malondialdehyde. High-dose TCS exposure induced histological changes as evidenced by reduction of Bowman's space, occlusion of the tubular lumen, and degeneration of tubular epithelial cells in the kidney. Tubular necrosis was confirmed as evidenced by a rise in expression of high mobility group box 1 renal protein. Daily sperm production was significantly diminished by high doses of TCS with marked inhibition of androgen receptor protein expression. Our results indicated that subchronic exposure to excessively high concentrations of 750 mg/kg TCS induced hepatorenal and reproductive toxicities in prepubertal male rats; however, the biological relevance of these findings is questionable as these drug levels are not encountered in the environment.

Evaluation of triclosan in the Hershberger and H295R steroidogenesis assays

Triclosan (TCS) is an antibacterial widely used in personal care products that exhibits endocrine disrupting activity in several species, with reports of altered thyroid, estrogen and androgen signaling pathways. To evaluate the androgenic mode of action, TCS was evaluated for androgen receptor mediated effects in the Hershberger assay and for altered androgen synthesis in the H295R steroidogenesis assay. In the Hershberger assay, castrated males were dosed by oral gavage for 10 days with corn oil (vehicle) or TCS (50 or 200 mg/kg/day) in the presence or absence of testosterone proprionate (TP, 0.2 mg/kg/day) prior to assessing accessory sex tissues (ASTs) weights. TCS alone or in combination with TP did not alter androgen dependent AST weights. Assessment of serum thyroxine (T4) demonstrated a significant dose-dependent decrease by TCS (50 or 200 mg/kg/day) co-administered with TP and TCS (200 mg/kg) without TP, but no differences in liver or thyroid weights. In the H295R assay, TCS from 0.01 to 10 μM had no effect on testosterone production but TCS at 3 μM and above did induce a significant increase in estrogen production. At 10 μM, TCS produced significant cytotoxicity which confounded the interpretation of the estrogenic effect at that concentration. Thus, TCS had no effect on androgen synthesis or activity in the models used, but did enhance estrogen production and suppress serum T4.

Urinary level of triclosan in a population of Chinese pregnant women and its association with birth outcomes

Triclosan (TCS) is a suspected endocrine disrupting chemical which is widely used in consumer products as an antibacterial agent. But findings in human studies focusing on the fetal developmental effects of prenatal TCS exposure were rare and inconsistent. This study aimed to determine maternal urinary TCS and investigate its association with birth outcomes. Pregnant women (n = 1006) were randomly selected from the prospective Healthy Baby Cohort (HBC) enrolled in 2014. TCS levels were determined in maternal urine samples collected at delivery and recorded birth outcomes were obtained from the medical records. Multiple linear regressions were applied to evaluate associations of maternal urinary TCS levels with birth outcomes including birth weight, birth length, and gestational age. Logistic regressions were used to evaluate associations with preterm birth, late term birth, and low birth weight. The geometric mean concentrations for TCS and specific gravity (SG) adjusted TCS in maternal urines were 0.73, 0.78 ng/mL, respectively. In the crude model, one ln-unit increase of urinary SG-adjusted TCS concentration was associated with a 0.30-day [95% confidence interval (CI): 0.00, 0.60] increase in gestational age; however, the associations were not statistically significant after adjustment for covariates. No significant associations of SG-adjusted TCS concentrations with birth weight and birth length were observed. Maternal SG-adjusted TCS concentrations were not related to preterm birth, late term birth, and low birth weight (all p > 0.10). Our findings reported a relatively low level of TCS among Chinese pregnant women. With such exposure level, we did not find strong evidence for associations between maternal TCS exposure and birth outcomes. Longitudinal studies concerning about different potential effects of TCS on perinatal health are necessary.

Impact of Triclosan on Female Reproduction through Reducing Thyroid Hormones to Suppress Hypothalamic Kisspeptin Neurons in Mice

Triclosan (TCS), a broad-spectrum antimicrobial agent, is widely used in clinical settings and various personal care products. The aim of this study was to evaluate the influence of TCS on reproductive endocrine and function. Here, we show that the exposure of adult female mice to 10 or 100 mg/kg/day TCS caused prolongation of diestrus, and decreases in antral follicles and corpora lutea within 2 weeks. TCS mice showed decreases in the levels of serum luteinizing hormone (LH), follicle-stimulating hormone (FSH) and progesterone, and gonadotrophin-releasing hormone (GnRH) mRNA with the lack of LH surge and elevation of prolactin (PRL). TCS mice had lower kisspeptin immunoreactivity and kiss1 mRNA in anteroventral periventricular nucleus (AVPV) and arcuate nucleus (ARC). Moreover, the estrogen (E2)-enhanced AVPV-kisspeptin expression was reduced in TCS mice. In addition, the serum thyroid hormones (triiodothyronine (T3) and thyroxine (T4)) in TCS mice were reduced with increases in levels of thyroid stimulating hormone (TSH) and thyroid releasing hormone (TRH). In TCS mice, the treatment with Levothyroxine (L-T4) corrected the increases in PRL, TSH and TRH; the administration of L-T4 or type-2 dopamine receptors agonist quinpirole inhibiting PRL release could rescue the decline of kisspeptin expression in AVPV and ARC; the treatment with L-T4, quinpirole or the GPR45 agonist kisspeptin-10 recovered the levels of serum LH and FSH and progesterone, and GnRH mRNA. Furthermore, TCS mice treated with L-T4 or quinpirole resumed regular estrous cycling, follicular development and ovulation. Together, these results indicate that exposing adult female mice to TCS (≥10 mg/kg) reduces thyroid hormones causing hyperprolactinemia that then suppresses hypothalamic kisspeptin expression, leading to deficits in reproductive endocrine and function.

Comparison of methods for calculating the health costs of endocrine disrupters: a case study on triclosan

BACKGROUND

Socioeconomic analysis is currently used in the Europe Union as part of the regulatory process in Regulation Registration, Evaluation and Authorisation of Chemicals (REACH), with the aim of assessing and managing risks from dangerous chemicals. The political impact of the socio-economic analysis is potentially high in the authorisation and restriction procedures, however, current socio-economic analysis dossiers submitted under REACH are very heterogeneous in terms of methodology used and quality. Furthermore, the economic literature is not very helpful for regulatory purposes, as most published calculations of health costs associated with chemical exposures use epidemiological studies as input data, but such studies are rarely available for most substances. The quasi-totality of the data used in the REACH dossiers comes from toxicological studies.

METHODS

This paper assesses the use of the integrated probabilistic risk assessment, based on toxicological data, for the calculation of health costs associated with endocrine disrupting effects of triclosan. The results are compared with those obtained using the population attributable fraction, based on epidemiological data.

RESULTS

The results based on the integrated probabilistic risk assessment indicated that 4894 men could have reproductive deficits based on the decreased vas deferens weights observed in rats, 0 cases of changed T₃ levels, and 0 cases of girls with early pubertal development. The results obtained with the Population Attributable Fraction method showed 7,199,228 cases of obesity per year, 281,923 girls per year with early pubertal development and 88,957 to 303,759 cases per year with increased total T₃ hormone levels. The economic costs associated with increased BMI due to TCS exposure could be calculated. Direct health costs were estimated at €5.8 billion per year.

CONCLUSIONS

The two methods give very different results for the same effects. The choice of a toxicological-based or an epidemiological-based method in the socio-economic analysis will therefore significantly impact the estimated health costs and consequently the political risk management decision. Additional work should be done for understanding the reasons of these significant differences.

Exposure to endocrine disruptors during adulthood: consequences for female fertility

Endocrine disrupting chemicals are ubiquitous chemicals that exhibit endocrine disrupting properties in both humans and animals. Female reproduction is an important process, which is regulated by hormones and is susceptible to the effects of exposure to endocrine disrupting chemicals. Disruptions in female reproductive functions by endocrine disrupting chemicals may result in subfertility, infertility, improper hormone production, estrous and menstrual cycle abnormalities, anovulation, and early reproductive senescence. This review summarizes the effects of a variety of synthetic endocrine disrupting chemicals on fertility during adult life. The chemicals covered in this review are pesticides (organochlorines, organophosphates, carbamates, pyrethroids, and triazines), heavy metals (arsenic, lead, and mercury), diethylstilbesterol, plasticizer alternatives (di-(2-ethylhexyl) phthalate and bisphenol A alternatives), 2,3,7,8-tetrachlorodibenzo-p-dioxin, nonylphenol, polychlorinated biphenyls, triclosan, and parabens. This review focuses on the hypothalamus, pituitary, ovary, and uterus because together they regulate normal female fertility and the onset of reproductive senescence. The literature shows that several endocrine disrupting chemicals have endocrine disrupting abilities in females during adult life, causing fertility abnormalities in both humans and animals.

Exposure of pregnant mice to triclosan impairs placental development and nutrient transport

Triclosan (TCS) is associated with spontaneous abortions and fetal growth restriction. Here, we showed that when pregnant mice were treated with 8 mg/kg TCS (8-TCS mice) on gestational days (GD) 6–18 fetal body weights were lower than controls. Placental weights and volumes were reduced in 8-TCS mice. The placental proliferative cells and expression of PCNA and Cyclin D3 on GD13 were remarkably decreased in 8-TCS mice. The decreases in activities and expression of placental System A amino acid or glucose transporters on GD14 and GD17 were observed in 8-TCS mice. Levels of serum thyroxine (T4) and triiodothyronine (T3) were lower in 8-TCS mice than those in controls. Declines of placental Akt, mTOR and P70S6K phosphorylation in 8-TCS mice were corrected by L-thyroxinein (T4). Treating 8-TCS mice with T4 rescued the placental cell proliferation and recovered the activity and expression of amino acid and glucose transporters, which were sensitive to mTOR inhibition by rapamycin. Furthermore, the replacement of T4 could rescue the decrease in fetal body weight, which was blocked by rapamycin. These findings indicate that TCS-induced hypothyroxinemia in gestation mice through reducing Akt-mTOR signaling may impair placental development and nutrient transfer leading to decreases in fetal body weight.

Changes in mammary histology and transcriptome profiles by low-dose exposure to environmental phenols at critical windows of development

Exposure to environmental chemicals has been linked to altered mammary development and cancer risk at high doses using animal models. Effects at low doses comparable to human exposure remain poorly understood, especially during critical developmental windows. We investigated the effects of two environmental phenols commonly used in personal care products - methyl paraben (MPB) and triclosan (TCS) - on the histology and transcriptome of normal mammary glands at low doses mimicking human exposure during critical windows of development. Sprague-Dawley rats were exposed during perinatal, prepubertal and pubertal windows, as well as from birth to lactation. Low-dose exposure to MPB and TCS induced measurable changes in both mammary histology (by Masson's Trichrome Stain) and transcriptome (by microarrays) in a window-specific fashion. Puberty represented a window of heightened sensitivity to MPB, with increased glandular tissue and changes of expression in 295 genes with significant enrichment in functions such as DNA replication and cell cycle regulation. Long-term exposure to TCS from birth to lactation was associated with increased adipose and reduced glandular and secretory tissue, with expression alterations in 993 genes enriched in pathways such as cholesterol synthesis and adipogenesis. Finally, enrichment analyses revealed that genes modified by MPB and TCS were over-represented in human breast cancer gene signatures, suggesting possible links with breast carcinogenesis. These findings highlight the issues of critical windows of susceptibility that may confer heightened sensitivity to environmental insults and implicate the potential health effects of these ubiquitous environmental chemicals in breast cancer.

Is Triclosan a neurotoxic agent?

Triclosan (TCS) is an antibacterial agent that has been used in many products since 1960s. Given its broad usage as an antiseptic TCS is present ubiquitously in the environment. Trace levels of TCS continue to be detected in many organisms, and it has been shown to be particularly toxic to aquatic species. The mechanisms underlying TCS-mediated toxicity include hormone dyshomeostasis, induction of oxidative stress, apoptosis and inflammation. Although TCS has been considered to be non-toxic to mammals, the adverse effects of continuous, long-term and low concentration exposure remain unknown. Epidemiological studies revealed that levels of TCS in human tissues, urine, plasma and breast milk correlate with the usage of this antimicrobial. This led to concerns regarding TCS safety and potential toxicity in humans, with special emphasis on early development. The Food and Drug Administration (FDA) recently issued a directive banning the use of TCS in consumer soaps, justifying the move attributed to data gaps on its effectiveness and safety, indicating the need for more studies addressing this chemical-mediated effects on various tissues including the central nervous system (CNS). The aim of this review was to (1) summarize the current findings on the neurotoxic effects of TCS and given the paucity of data, to (2) broaden the discussion to other effects of TCS, which might plausibly be related to neuronal functions.