Triclosan exposure, transformation, and human health effects

Characterizing the effects of triclosan and triclocarban on the intestinal epithelial homeostasis using small intestinal organoids

Intestinal epithelium has the largest surface of human body, contributes dramatically to defense of toxicant-associated intestinal injury. Triclosan (TCS) and triclocarban (TCC), extensively employed as antibacterial agents in personal care products (PCPs) and healthcare facilities, caused serious damage to human intestine. However, the role of the intestinal epithelium in TCS/TCC-induced intestinal toxicity and its underlying toxic mechanisms remain incompletely understood. In this study, a novel 3D intestinal organoid model was utilized to investigate that exposure to TCS/TCC led to a compromised self-renewal and differentiation of intestinal stem cells (ISCs). Consequently, this disrupted intestinal epithelial homeostasis ultimately caused a reduction in nutrient absorption and deficient of epithelial defense to exogenous and endogenous pathogens stimulation. The inhibition of the Wnt signaling pathway in intestinal stem cell was contributed to the intestinal toxicity of TCS/TCC. These results were further confirmed in vivo with mice exposed to TCS/TCC. The findings of this study provide evidence that TCS/TCC possess the capacity to disturb the homeostasis of the intestinal epithelium, and emphasize the credibility of organoids as a valuable model for toxicological studies, as they could faithfully recapitulate in vivo phenomena.

Research on antibiotic resistance genes in wild and artificially bred green turtles (Chelonia mydas)

Sea turtles, vital to marine ecosystems, face population decline. Artificial breeding is a recovery strategy, yet it risks introducing antibiotic resistance genes (ARGs) to wild populations and ecosystems. This study employed metagenomic techniques to compare the distribution characteristics of ARGs in the guts of wild and artificially bred green turtles (Chelonia mydas). The findings revealed that the total abundance of ARGs in C. mydas that have been artificially bred was significantly higher than that in wild individuals. Additionally, the abundance of mobile genetic elements (MGEs) co-occurring with ARGs in artificially bred C. mydas was significantly higher than in wild C. mydas. In the analysis of bacteria carrying ARGs, wild C. mydas exhibited greater bacterial diversity. Furthermore, in artificially bred C. mydas, we discovered 23 potential human pathogenic bacteria (HPB) that contain antibiotic resistance genes. In contrast, in wild C. mydas, only one type of HPB carrying an antibiotic resistance gene was found. The findings of this study not only enhance our understanding of the distribution and dissemination of ARGs within the gut microbial communities of C. mydas, but also provide vital information for assessing the potential impact of releasing artificially bred C. mydas on the spread of antibiotic resistance.

Integrative transcriptomic analysis reveals a broad range of toxic effects of triclosan on coral Porites lutea

Triclosan (TCS) is an antimicrobial agent commonly used in personal care products. However, little is known about its toxicity to corals. Here, we examined the acute toxic effects (96 h) of TCS at different levels to the coral Porites lutea. Results showed that the bioaccumulation factors (BAFs) of TCS in Porites lutea decreased with increasing TCS exposure levels. Exposure to TCS at the level up to 100 μg/L did not induce bleaching of Porites lutea. However, by the end of the experiment, both the density and chlorophyll a content of the symbiotic zooxanthellae were 19-52 % and 19.9-45.6 % lower in the TCS treatment groups than in the control, respectively. For the coral host, its total antioxidant capacity (T-AOC), superoxide dismutase (SOD) and catalase (CAT) activities were all significantly lower in the TCS treatment groups than the control. Transcriptome analysis showed that 942 and 1077 differentially expressed genes (DEGs) were identified in the coral host in the 0.5 and 100 μg/L TCS treatment groups, respectively. Meanwhile, TCS can interfere with pathways related to immune system and reproductive system in coral host. Overall, our results suggest that environmentally relevant concentrations of TCS can impact both the coral host and the symbiotic zooxanthellae.

Triclosan affects steroidogenesis in mouse primary astrocytes in vitro with engagement of Sirtuin 1 and 3

Triclosan (TCS) is a widely used antimicrobial, antifungal, and antiviral agent. To date, it has been reported that TCS can enter the human body and disrupt hormonal homeostasis. Therefore, the aim of our paper was to evaluate the impact of TCS on astrocytes, i.e. a crucial population of cells responsible for steroid hormone production. Our data showed that, in mouse primary astrocyte cultures, TCS can act as an endocrine disrupting chemical through destabilization of the production or secretion of progesterone (P4), testosterone (T), and estradiol (E2). TCS affects the mRNA expression of enzymes involved in neurosteroidogenesis, such as Cyp17a1, 17β-Hsd, and Cyp19a1. Our data showed that a partial PPARγ agonist (honokiol) prevented changes in Cyp17a1 mRNA expression caused by TCS. Similarly, honokiol inhibited TCS-stimulated P4 release. However, rosiglitazone (classic PPARγ agonist) or GW9662 (PPARγ antagonist) had a much stronger effect. Therefore, we believe that the changes observed in the P4, T, and E2 levels are a result of dysregulation of the activity of the aforementioned enzymes, whose expression can be affected by TCS through a Pparγ-dependent pathway. TCS was found to decrease the aryl hydrocarbon receptor (AhR) and Sirtuin 3 protein levels, which may be the result of the activation of the these proteins. Since our study showed dysregulation of the production or secretion of neurosteroids in astrocytes, it can be concluded that TCS reaching the brain may contribute to the development of neurodegenerative diseases in which an abnormal amount of neurosteroids is observed.

Triclosan impairs spermatocyte cell proliferation and induces autophagy by regulating microRNA-20a-5 P by pargeting PTEN

BACKGROUND

Triclosan (TCS), as an endocrine disrupter, has been found to affect male fertility. However, the potential molecular mechanism is still unknown. We aimed to investigate whether the toxic effects of TCS on spermatocyte cells was mediated by the regulation of microRNA-20a-5 P on PTEN.

METHODS

GC-2 and TM4 cells were treated with TCS (0.5-80 μM) for 24 or 48 hours. Effect of TCS on proliferation of GC-2 and TM4 cells was detected using a cell counting kit-8 (CCK8) assay. Expression of miR-17 family and autophagy genes were detected. The interaction between miR-20a-5 P and PTEN was determined by a dual-luciferase reporter assay.

RESULTS

TCS decreased cell proliferation of GC-2 and TM4 cells. Expression of autophagy-related genes and miR-17 family was altered by TCS. PTEN expression was significantly increased, whereas the expression of miR-20a-5 P was significantly decreased in GC-2 and TM4 cells. As predicted in relevant databases, there is a binding site of miR-20a-5 P in PTEN. The expression of PTEN was significantly down-regulated by the miR-20a-5 P mimic.

CONCLUSION

As a downstream target of miR-20a-5 P, PTEN functioned in the autophagy process of which TCS inhibited the proliferation of spermatocyte cells. Our results provided new ideas for revealing the molecular mechanism and protective strategy on male infertility.

Bisphenol S Promotes the Transfer of Antibiotic Resistance Genes via Transformation

The antibiotic resistance crisis has seriously jeopardized public health and human safety. As one of the ways of horizontal transfer, transformation enables bacteria to acquire exogenous genes naturally. Bisphenol compounds are now widely used in plastics, food, and beverage packaging, and have become a new environmental pollutant. However, their potential relationship with the spread of antibiotic resistance genes (ARGs) in the environment remains largely unexplored. In this study, we aimed to assess whether the ubiquitous bisphenol S (BPS) could promote the transformation of plasmid-borne ARGs. Using plasmid pUC19 carrying the ampicillin resistance gene as an extracellular ARG and model microorganism E. coli DH5α as the recipient, we established a transformation system. Transformation assays revealed that environmentally relevant concentrations of BPS (0.1-10 μg/mL) markedly enhanced the transformation frequency of plasmid-borne ARGs into E. coli DH5α up to 2.02-fold. Fluorescent probes and transcript-level analyses suggest that BPS stimulated increased reactive oxygen species (ROS) production, activated the SOS response, induced membrane damage, and increased membrane fluidity, which weakened the barrier for plasmid transfer, allowing foreign DNA to be more easily absorbed. Moreover, BPS stimulates ATP supply by activating the tricarboxylic acid (TCA) cycle, which promotes flagellar motility and expands the search for foreign DNA. Overall, these findings provide important insight into the role of bisphenol compounds in facilitating the horizontal spread of ARGs and emphasize the need to monitor the residues of these environmental contaminants.

Exposure to zinc and dialkyldimethyl ammonium compound alters bacterial community structure and resistance gene levels in partial sulfur autotrophic denitrification coupled with the Anammox process

Dialkyldimethyl ammonium compound (DADMAC) is widely used in daily life as a typical disinfectant and often co-exists with the heavy metal zinc in sewage environments. This study investigated the effects of co-exposure to zinc (1 mg/L) and DADMAC (0.2-5 mg/L) on the performance, bacterial community, and resistance genes (RGs) in a partial sulfur autotrophic denitrification coupled with anaerobic ammonium oxidation (PSAD-Anammox) system in a sequencing batch moving bed biofilm reactor for 150 days. Co-exposure to zinc and low concentration (0.2 mg/L) DADMAC did not affect the nitrogen removal ability of the PASD-Anammox system, but increased the abundance and transmission risk of free RGs in water. Co-exposure to zinc and medium-to-high (2-5 mg/L) DADMAC led to fluctuations in and inhibition of nitrogen removal, which might be related to the enrichment of heterotrophic denitrifying bacteria dominated by Denitratisoma. Co-exposure to zinc and high concentration DADMAC (5 mg/L) stimulated the secretion of extracellular polymeric substances and increased the proliferation risk of intracellular RGs in sludge. This study provided insights into the application of PSAD-Anammox system and the ecological risks of wastewater containing zinc and DADMAC.

Long-life triclosan exposure induces ADHD-like behavior in rats via prefrontal cortex dopaminergic deficiency

In recent years, exposure to triclosan (TCS) has been linked to an increase in psychiatric disorders. Nonetheless, the precise mechanisms of this occurrence remain elusive. Therefore, this study developed a long-life TCS-exposed rat model, an SH-SY5Y cell model, and an atomoxetine hydrochloride (ATX) treatment model to explore and validate the neurobehavioral mechanisms of TCS from multiple perspectives. In the long-life TCS-exposed model, pregnant rats received either 0 mg/kg (control) or 50 mg/kg TCS by oral gavage throughout pregnancy, lactation, and weaning of their offspring (up to 8 weeks old). In the ATX treatment model, weanling rats received daily injections of either 0 mg/kg (control) or 3 mg/kg ATX via intraperitoneal injection until they reached 8 weeks old. Unlike the TCS model, ATX exposure only occurred after the pups were weaned. The results indicated that long-life TCS exposure led to attention-deficit hyperactivity disorder (ADHD)-like behaviors in male offspring rats accompanied by dopamine-related mRNA and protein expression imbalances in the prefrontal cortex (PFC). Moreover, in vitro experiments also confirmed these findings. Mechanistically, TCS reduced dopamine (DA) synthesis, release, and transmission, and increased reuptake in PFC, thereby reducing synaptic gap DA levels and causing dopaminergic deficits. Additional experiments revealed that increased DA concentration in PFC by ATX effectively alleviated TCS-induced ADHD-like behavior in male offspring rats. These findings suggest that long-life TCS exposure causes ADHD-like behavior in male offspring rats through dopaminergic deficits. Furthermore, ATX treatment not only reduce symptoms in the rats, but also reveals valuable insights into the neurotoxic mechanisms induced by TCS.

The effect of endocrine-disrupting chemicals in follicular fluid: The insights from oocyte to fertilization

Endocrine-disrupting chemicals (EDCs) exhibited the detriment in female reproductive health. Our objective was to investigate the individual and mixture effects of EDCs present in follicular fluid, the environment in which oocytes grow and develop, on early reproductive outcomes. We recruited 188 women seeking reproduction examination from the Study of Exposure and Reproductive Health (SEARCH) cohort between December 2020 and November 2021. We assessed the concentrations of 7 categories of 64 EDCs in follicular fluid, and measured early reproductive outcomes, including retrieved oocytes, mature oocytes, normal fertilized oocytes, and high-quality embryos. In this study Monomethyl phthalate (MMP) (2.17 ng/ml) were the compounds found in the highest median concentrations in follicular fluid. After adjusting for multiple testing, multivariate regression showed that multiple EDCs were significantly negatively associated with early assisted reproduction outcomes. For example, MMP showed a significant negative correlation with the number of high quality embryos (β: -0.1, 95 % CI: -0.15, -0.04). Specifically, eight types of EDCs were significantly negatively associated with four early assisted reproductive outcomes (β range: -0.2 ∼ -0.03). In the mixed exposure model, we found that mixtures of EDC were significantly negatively correlated with all four outcomes. In the quantile g-computation (QGCOMP) model, for each interquartile range increase in the concentration of EDC mixtures, the number of oocytes retrieved, mature oocytes, normally fertilized oocytes, and high-quality embryos decreased by 0.46, 0.52, 0.77, and 1.2, respectively. Moreover, we identified that phthalates (PAEs) predominantly contributed to the negative effects. Future research should validate our findings.

Cell-free hemoglobin and hemin catalyzing triclosan oxidative coupling in plasma: A novel exogenous phenolic pollutants coupling pathway

Previous studies reported that hemoprotein CYP450 catalyzed triclosan coupling is an "uncommon" metabolic pathway that may enhance toxicity, raising concerns about its environmental and health impacts. Hemoglobin, a notable hemoprotein, can catalyze endogenous phenolic amino acid tyrosine coupling reactions. Our study explored the feasibility of these coupling reactions for exogenous phenolic pollutants in plasma. Both hemoglobin and hemin were found to catalyze triclosan coupling in the presence of H₂O₂. This resulted in the formation of five diTCS-2 H, two diTCS-Cl-3 H, and twelve triTCS-4 H in phosphate buffer, with a total of nineteen triclosan coupling products monitored using LC-QTOF. In plasma, five diTCS-2 H, two diTCS-Cl-3 H, and two triTCS-4 H were detected in hemoglobin-catalyzed reactions. Hemin showed a weaker catalytic effect on triclosan transformation compared to hemoglobin, likely due to hemin dimerization and oxidative degradation by H₂O₂, which limits its catalytic efficiency. Triclosan transformation in the human plasma-like medium still occurs with high H₂O₂, despite the presence of antioxidant proteins that typically inhibit such transformations. In plasma, free H₂O₂ was depleted within 40 minutes when 800 µM H₂O₂ was added, suggesting a rapid consumption of H₂O₂ in these reactions. Antioxidative species, or hemoglobin/hemin scavengers such as bovine serum albumin, may inhibit but not completely terminate the triclosan coupling reactions. Previous studies reported that diTCS-2 H showed higher hydrophobicity and greater endocrine-disrupting effects compared to triclosan, which further underscores the potential health risks. This study indicates that hemoglobin and heme in human plasma might significantly contribute to phenolic coupling reactions, potentially increasing health risks.

Association of Phenols, Parabens, and Their Mixture with Maternal Blood Pressure Measurements in the PROTECT Cohort

BACKGROUND

Phenols and parabens are two classes of high production volume chemicals that are used widely in consumer and personal care products and have been associated with reproductive harm and pregnancy complications, such as preeclampsia and gestational diabetes. However, studies examining their influence on maternal blood pressure and gestational hypertension are limited.

OBJECTIVES

We investigated associations between individual phenols, parabens, and their mixture on maternal blood pressure measurements, including systolic and diastolic blood pressure (SBP and DBP) and hypertension during pregnancy (defined as stage 1 or 2 hypertension), among N = 1,433 Puerto Rico PROTECT study participants.

METHODS

We examined these relationships cross-sectionally at two time points during pregnancy (16-20 and 24-28 wks gestation) and longitudinally using linear mixed models (LMMs). Finally, we used quantile g-computation to examine the mixture effect on continuous (SBP, DBP) and binary (hypertension during pregnancy) blood pressure outcomes.

RESULTS

We observed a trend of higher odds of hypertension during pregnancy with exposure to multiple analytes and the overall mixture [including bisphenol A (BPA), bisphenol S (BPS), triclocarbon (TCC), triclosan (TCS), benzophenone-3 (BP-3), 2,4-dichlorophenol (2,4-DCP), 2,5-dichlorophenol (2,5-DCP), methyl paraben (M-PB), propyl paraben (P-PB), butyl paraben (B-PB), and ethyl paraben (E-PB)], especially at 24-28 wk gestation, with an adjusted mixture odds ratio ( OR ) = 1.57 (95% CI: 1.03, 2.38). Lower SBP and higher DBP were also associated with individual analytes, with results from LMMs most consistent for methyl paraben (M-PB) or propyl paraben (P-PB) and increased DBP across pregnancy [adjusted M-PB β = 0.78 (95% CI: 0.17, 1.38) and adjusted P-PB β = 0.85 (95% CI: 0.19, 1.51)] and for BPA, which was associated with decreased SBP (adjusted β = - 0.57 ; 95% CI: - 1.09 , - 0.05 ). Consistent with other literature, we also found evidence of effect modification by fetal sex, with a strong inverse association observed between the overall exposure mixture and SBP at visit 1 among participants carrying female fetuses only.

CONCLUSIONS

Our findings indicate that phenol and paraben exposure may collectively increase the risk of stage 1 or 2 hypertension during pregnancy, which has important implications for fetal and maternal health. https://doi.org/10.1289/EHP14008.

Toxicity evolution of triclosan during environmental transformation and human metabolism: Misgivings in the post-pandemic era

In the context of pandemic viruses and pathogenic bacteria, triclosan (TCS), as a typical antibacterial agent, is widely used around the world. However, the health risks from TCS increase with exposure, and it is widespread in environmental and human samples. Notably, environmental transformation and human metabolism could induce potentially undesirable risks to humans, rather than simple decontamination or detoxification. This review summarizes the environmental and human exposure to TCS covering from 2004 to 2023. Particularly, health impacts from the environmental and metabolic transformation of TCS are emphasized. Environmental transformations aimed at decontamination are recognized to form carcinogenic products such as dioxins, and ultraviolet light and excessive active chlorine can promote the formation of these dioxin congeners, potentially threatening environmental and human health. Although TCS can be rapidly metabolized for detoxification, these processes can induce the formation of lipophilic ether metabolic analogs via cytochrome P450 catalysis, causing possible adverse cross-talk reactions in human metabolic disorders. Accordingly, TCS may be more harmful in environmental transformation and human metabolism. In particular, TCS can stimulate the transmission of antibiotic resistance even at trace levels, threatening public health. Considering these accruing epidemiological and toxicological studies indicating the multiple adverse health outcomes of TCS, we call on environmental toxicologists to pay more attention to the toxicity evolution of TCS during environmental transformation and human metabolism.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Monitoring human exposure to four parabens and triclosan: comparing silicone wristbands with spot urine samples as predictors of internal dose

BACKGROUND

People are exposed to a variety of chemicals each day as a result of their personal care product (PCP) use.

OBJECTIVE

This study was designed to determine if silicone wristbands provide a quantitative estimate of internal dose for phenols commonly associated with PCPs, with a focus on triclosan and four parabens: methyl-, ethyl-, propyl-, and butylparaben. Uptake of these compounds into wristbands and correlations with internal dose were assessed.

METHODS

Ten adults from central North Carolina wore five silicone wristbands, with one wristband removed each day for 5 days. Each participant provided a 24 h urine sample and a random spot urine sample each day, in which paraben and triclosan metabolites were evaluated.

RESULTS

All parabens and triclosan were detected frequently in wristbands and, except for butylparaben, in urine samples. Wristband and spot urine concentrations of parabens and triclosan were both compared to a measurement of internal dose (i.e., the total metabolite mass excreted over 5 days as a measurement of internal dose).

IMPACT STATEMENT

The two most hydrophobic compounds investigated, butylparaben and triclosan, displayed significant linear uptake in wristbands over 5 days, whereas concentrations of methyl- and ethylparaben displayed a steady state concentration. In general, wristbands and spot urine samples were similarly correlated to internal dose for frequently detected parabens and triclosan.  However, wristbands have additional advantages including higher detection rates and reduced participant burden that may make them more suitable tools for assessing exposure to PCPs.

Gender-specific effects of polystyrene nanoplastic exposure on triclosan-induced reproductive toxicity in zebrafish (Danio rerio)

Nanoplastics (NPs) and triclosan (TCS) are ubiquitous emerging environmental contaminants detected in human samples. While the reproductive toxicity of TCS alone has been studied, its combined effects with NPs remain unclear. Herein, we employed Fourier transform infrared spectroscopy and dynamic light scattering to characterize the coexposure of polystyrene nanoplastics (PS-NPs, 50 nm) with TCS. Then, adult zebrafish were exposed to TCS at environmentally relevant concentrations (0.361-48.2 μg/L), with or without PS-NPs (1.0 mg/L) for 21 days. TCS biodistribution in zebrafish tissues was investigated using ultra-performance liquid chromatography coupled with triple quadrupole mass spectrometry. Reproductive toxicity was assessed through gonadal histopathology, fertility tests, changes in steroid hormone synthesis and gene expression within the hypothalamus-pituitary-gonad-liver (HPGL) axis. Transcriptomics and proteomics were applied to explore the underlying mechanisms. The results showed that PS-NPs could adsorb TCS, thus altering the PS-NPs' physical characteristics. Our observations revealed that coexposure with PS-NPs reduced TCS levels in the ovaries, livers, and brains of female zebrafish. Conversely, in males, coexposure with PS-NPs increased TCS levels in the testes and livers, while decreasing them in the brain. We found that co-exposure mitigated TCS-induced ovary development inhibition while exacerbated TCS-induced spermatogenesis suppression, resulting in increased embryonic mortality and larval malformations. This co-exposure influenced the expression of genes linked to steroid hormone synthesis (cyp11a1, hsd17β, cyp19a1) and attenuated the TCS-decreased estradiol (E2) in females. Conversely, testosterone levels were suppressed, and E2 levels were elevated due to the upregulation of specific genes (cyp11a1, hsd3β, cyp19a1) in males. Finally, the integrated analysis of transcriptomics and proteomics suggested that the aqp12-dctn2 pathway was involved in PS-NPs' attenuation of TCS-induced reproductive toxicity in females, while the pck2-katnal1 pathway played a role in PS-NPs' exacerbation of TCS-induced reproductive toxicity in males. Collectively, PS-NPs altered TCS-induced reproductive toxicity by disrupting the HPGL axis, with gender-specific effects.

Recent use of consumer and personal care products and exposures to select endocrine disrupting chemicals among urban children with asthma

BACKGROUND

Emerging studies suggest that endocrine disrupting chemicals (EDCs) in personal care and other consumer products are linked with various adverse health effects, including respiratory and reproductive effects. Despite Black persons using more personal care products than other demographic groups and having a high asthma burden, little is known regarding their consumer product use patterns and associated EDC exposures.

OBJECTIVE

To examine the association between recent exposure to select EDCs with specific consumer products and behaviors in a cohort of 110 predominantly Black children with asthma, ages 8-17 years, living in Baltimore City, Maryland.

METHODS

We quantified concentrations of bisphenol A (BPA), bisphenol S (BPS), bisphenol F, two dichlorophenols, four parabens, triclosan, benzophenone-3, and triclocarban in spot urine samples. Questionnaires were used to capture recent (last 24-h) consumer product use and behaviors. Associations between EDCs and consumer product uses/behaviors were assessed using multivariable linear regression, adjusting for age, gender, race/ethnicity, and caregiver income level. Effect estimates were expressed as geometric mean ratios of biomarker concentrations of product-users vs non-users.

RESULTS

Increased concentrations to select EDCs were associated with recent use of air freshener (ratios; BPA: 1.9, 95%CI 1.4-2; BPS 1.7, 95%CI 1-2.97; propyl paraben: 3.0, 95%CI 1.6-5.6), scented candles (methyl paraben: 2.6, 95%CI 1.1-6.1), and scented carpet powder (2,5-dichlorophenol: 2.8, 95%CI 1.2-6.3). Additionally, consuming canned food was associated with some increased biomarker concentrations (ratios: BPA: 1.7, 95%CI 1.2-2.4; BPS: 2.1, 95% CI: 1.2-3.6).

SIGNIFICANCE

These findings add to the body of evidence suggesting that recent use of select consumer products in Black children contributes to exposure of chemicals of concern and could potentially inform exposure mitigation interventions. Findings have broad potential health implications for pediatric populations and Black children who may face exposure and health disparities.

IMPACT

Little is known about how children's personal care product use and consumer behaviors affect their exposures to endocrine disrupting chemicals (EDCs). This is particularly true for Black children who often experience a disparate exposure burden to many EDCs. This is a significant knowledge gap among children that are uniquely vulnerable to EDCs as they undergo critical windows of growth and development. Our findings show associations between consumer products and EDC exposures in predominantly Black children in low-income settings. Identifying EDC exposure determinants has broad health implications as many of these chemicals have been associated with adverse health risks.

Effects of 2,4-dichlorophenol on non-specific immunity, histopathological lesions, and redox balance in African Catfish, clarias gariepinus (Burchell, 1822)

The toxic effects of 2, 4-dichlorophenol (2, 4-DCP) on aquatic organisms are well-established; however, the details regarding the mechanisms underlying the toxicity, especially immunotoxicity are poorly understood. Consequently, the aim of this study was to investigate the histopathologic, oxidative stress and immunotoxic effects attributed to exposure to sublethal concentrations of 2,4-DCP in the African catfish, Clarias gariepinus. Juvenile C. gariepinus were exposed to 0.4, 0.8, or 1.6 mg/L 2, 4-DCP for 28 days after which blood and head kidney were extracted for the determination of various nonspecific innate immune parameters while the liver was excised for histopathology examination and measurement of oxidative stress biomarkers. Control fish were maintained in water spiked 10 µL/L ethanol, representing the solvent control. A significant increase was noted in the activities of lactate dehydrogenase and superoxide dismutase as well as in levels of lipid peroxidation and DNA fragmentation in a dose-dependent manner, with higher adverse effects observed at the highest concentration tested (1.6 mg/L). The total white blood cells (WBC) count was significantly elevated in fish exposed to 2,4-DCP compared to control. Myeloperoxidase content was decreased significantly in fish exposed to 2,4-DCP especially at the highest concentration (1.6 mg/L) compared to controls. The respiratory burst activity did not differ markedly amongst groups. Histopathological lesions noted included edema, leucocyte infiltration, and depletion of hemopoietic tissue in the head kidney of exposed fish. There was significant upregulation in the mRNA expression of tumor necrosis factor (TNF-α) and heat shock protein 70 (HSP 70) but downregulation of major histocompatibility complex 2 (MHC 2) in exposed fish. Data demonstrated that exposure to 2,4-DCP resulted in histopathological lesions, oxidative stress, and compromised immune system in C. gariepinus.

Current state of knowledge of triclosan (TCS)-dependent reactive oxygen species (ROS) production

Triclosan (TCS) is widely used in a number of industrial and personal care products. This molecule can induce reactive oxygen species (ROS) production in various cell types, which results in diverse types of cell responses. Therefore, the aim of the present study was to summarize the current state of knowledge of TCS-dependent ROS production and the influence of TCS on antioxidant enzymes and pathways. To date, the TCS mechanism of action has been widely investigated in non-mammalian organisms that may be exposed to contaminated water and soil, but there are also in vivo and in vitro studies on plants, algae, mammalians, and humans. This literature review has revealed that mammalian organisms are more resistant to TCS than non-mammalian organisms and, to obtain a toxic effect, the effective TCS dose must be significantly higher. The TCS-dependent increase in the ROS level causes damage to DNA, protein, and lipids, which together with general oxidative stress leads to cell apoptosis or necrosis and, in the case of cancer cells, faster oncogenesis and even initiation of oncogenic transformation in normal human cells. The review presents the direct and indirect TCS action through different receptor pathways.

Triclosan administration to humanized UDP-glucuronosyltransferase 1 neonatal mice induces UGT1A1 through a dependence on PPARα and ATF4

Triclosan (TCS) is an antimicrobial toxicant found in a myriad of consumer products and has been detected in human tissues, including breastmilk. We have evaluated the impact of lactational TCS on UDP-glucuronosyltransferase 1A1 (UGT1A1) expression and bilirubin metabolism in humanized UGT1 (hUGT1) neonatal mice. In hUGT1 mice, expression of the hepatic UGT1A1 gene is developmentally delayed resulting in elevated total serum bilirubin (TSB) levels. We found that newborn hUGT1 mice breastfed or orally treated with TCS presented lower TSB levels along with induction of hepatic UGT1A1. Lactational and oral treatment by gavage with TCS leads to the activation of hepatic nuclear receptors constitutive androstane receptor (CAR), peroxisome proliferator-activated receptor alpha (PPARα), and stress sensor, activating transcription factor 4 (ATF4). When CAR-deficient hUGT1 mice (hUGT1/Car-/-) were treated with TCS, TSB levels were reduced with a robust induction of hepatic UGT1A1, leaving us to conclude that CAR is not tied to UGT1A1 induction. Alternatively, when PPARα-deficient hUGT1 mice (hUGT1/Pparα-/-) were treated with TCS, hepatic UGT1A1 was not induced. Additionally, we had previously demonstrated that TCS is a potent inducer of ATF4, a transcriptional factor linked to the integrated stress response. When ATF4 was deleted in liver of hUGT1 mice (hUGT1/Atf4ΔHep) and these mice treated with TCS, we observed superinduction of hepatic UGT1A1. Oxidative stress genes in livers of hUGT1/Atf4ΔHep treated with TCS were increased, suggesting that ATF4 protects liver from excessive oxidative stress. The increase oxidative stress may be associated with superinduction of UGT1A1. The expression of ATF4 in neonatal hUGT1 hepatic tissue may play a role in the developmental repression of UGT1A1.

Effectiveness of a novel experimental herbal toothpaste against bacterial consortium associated with dental caries

Background

To evaluate the effectiveness of an experimental toothpaste based on Hypericum laricifolium Juss. essential oil against a bacterial consortium associated with dental caries.

Material and Methods

The antibacterial activity of the essential oil was evaluated by the disk diffusion and microdilution tests against Streptococcus mutans, Streptococcus sanguinis and Streptococcus salivarius. Petri dishes were incubated at 37°C for 24 h. An experimental toothpaste was prepared at a concentration of 201.76 mg/mL. The antibacterial activity of the experimental and six commercial toothpastes were evaluated by agar well-diffusion method. Petri dishes were inoculated with a bacterial consortium prepared with the three strains. 80 mg of the toothpastes were placed in the wells and the Petri dishes were incubated at 37°C for 24 h. The inhibition zones were measured with a digital compass. The differences between the pastas were evaluated with the one-way ANOVA test, with a 5% level of significance.

Results

The essential oil was more effective than 0.12% chlorhexidine in inhibiting the growth of S. mutans (29.02±1.74 mm) and S. sanguinis (21.92±3.43 mm), being more moderate for S. salivarius (17.66±1.11 mm) . In MBC tests, the EO showed complete inhibition of the growth of S. mutans at a concentration of 5% (50.44 mg/mL), 10% (100.88 mg/mL) for S. sanguinis and 2.5% (25.22 mg/mL) for S. salivarius. The experimental toothpaste was effective in inhibiting the growth of the bacterial consortium (31.88±66 mm), having a similar performance to Total Dent, Colgate Total 12, Kolynos® Herbal and Colgate® Herbal (p> 0.05).

Conclusions

The development of an experimental paste based on H. laricifolium Juss. essential oil (0.28% v/v) showed an important antibacterial activity similar to commercial toothpastes against a bacterial consortium of S. mutans, S. sanguinis and S. salivarius. Key words:Antibacterial agents, toothpastes, medicinal plants, Streptococcus mutans, Streptococcus sanguinis, Streptococcus salivarius.

Exploring Novel Antimalarial Compounds Targeting Plasmodium falciparum Enoyl-ACP Reductase: Computational and Experimental Insights

Malaria, caused by Plasmodium protozoa with Plasmodium falciparum as the most virulent species, continues to pose significant health challenges. Despite the availability of effective antimalarial drugs, the emergence of resistance has heightened the urgency for developing novel therapeutic compounds. In this study, we investigated the enoyl-ACP reductase enzyme of P. falciparum (PfENR) as a promising target for antimalarial drug discovery. Through a comprehensive analysis, we conducted a comparative evaluation of two lead compounds, LD1 (CID: 44405336, lead compounds 1) and LD2 (CID: 72703246, lead compounds 2), obtained from the PubChem/NCBI ligand database, to serve as reference molecules in the identification of potential derivatives using virtual screening assays. Among the newly identified candidates, Ligand 1 (LG1) and Ligand 2 (LG2) exhibited intriguing characteristics and underwent further investigation through docking and molecular dynamics simulations. Ligand 1 (LG1) demonstrated interactions similar to LD1, including hydrogen bonding with Asp218, while Ligand 2 (LG2) displayed superior binding energy comparable to LD1 and LD2, despite lacking hydrogen bonding interactions observed in the control compounds triclosan and its derivative 7-(4-chloro-2-hydroxyphenoxy)-4-methyl-2H-chromen-2-one (CHJ). Following computational validation using the MM/GBSA method to estimate binding free energy, commercially acquired LG1 and LG2 ligands were subjected to in vitro testing. Inhibition assays were performed to evaluate their potential as PfENR inhibitors alongside triclosan as a control compound. LG1 exhibited no inhibitory effects, while LG2 demonstrated inhibitory effects like triclosan. In conclusion, this study contributes valuable insights into developing novel antimalarial drugs by identifying LG2 as a potential ligand and employing a comprehensive approach integrating computational and experimental methodologies.

Dynamic alterations in physiological and biochemical indicators of Cirrhinus mrigala hatchlings: A sublethal exposure of triclosan

Triclosan (TCS), a biocide used in various day-to-day products, has been associated with several toxic effects in aquatic organisms. In the present study, biochemical and hematological alterations were evaluated after 14 d (sublethal) exposure of tap water (control), acetone (solvent control), 5, 10, 20, and 50 μg/L (environmentally relevant concentrations) TCS to the embryos/hatchlings of Cirrhinus mrigala, a major freshwater carp distributed in tropic and sub-tropical areas of Asia. A concentration-dependent increase in the content of urea and protein carbonyl, while a decrease in the total protein, glucose, cholesterol, triglycerides, uric acid, and bilirubin was observed after the exposure. Hematological analysis revealed a decrease in the total erythrocyte count, hemoglobin, and partial pressure of oxygen, while there was an increase in the total leucocyte count, carbon dioxide, and partial pressure of carbon dioxide and serum electrolytes. Comet assay demonstrates a concentration-dependent increase in tail length, tail moment, olive tail moment, and percent tail DNA. An amino acid analyzer showed a TCS-dose-dependent increase in various amino acids. Sodium dodecyl sulphate polyacrylamide gel electrophoresis analysis revealed different proteins ranging from 6.5 to 200 kDa, demonstrating TCS-induced upregulation. Fourier transform infrared spectra analysis exhibited a decline in peak area percents with an increase in the concentration of TCS in water. Curve fitting of amide I (1,700-1600 cm-1) showed a decline in α-helix and turns and an increase in β-sheets. Nuclear magnetic resonance study also revealed concentration-dependent alterations in the metabolites after 14 d exposure. TCS caused alterations in the biomolecules and heamatological parameters of fish, raising the possibility that small amounts of TCS may change the species richness in natural aquatic habitats. In addition, consuming TCS-contaminated fish may have detrimental effects on human health. Consequently, there is a need for the proper utilisation and disposal of this hazardous compound in legitimate quantities.

Triclosan, an antimicrobial drug, induced reproductive impairment in the freshwater fish, Anabas testudineus (Bloch, 1792)

Triclosan (TCS), an antimicrobial drug, is known to occupy different compartments in aquatic ecosystems. The present study focused to evaluate the reproductive toxicity of triclosan, at environmentally relevant (0.009 and 9 μg L-1) and sublethal (176.7 μg L-1) concentrations for 90 days in the pre-spawning phase of the fish, Anabas testudineus. The reproductive biomarkers, namely, gonadal steroidogenic enzymes, expression of aromatic genes, levels of serum gonadotropins, sex hormones, and histology of gonads were analyzed. The weight of the animal, brain weights along with gonadosomatic index decreased while mucus deposition increased significantly at all concentrations of triclosan as the primary defensive mechanism to prevent the entry of toxicants. Triclosan disrupted gonadal steroidogenesis as evidenced by a reduction in the activities of gonadal steroidogenic enzymes. The expressions of cyp19a1a and cyp19a1b genes were up-regulated in the brain of both sexes and testis, while down-regulated in the ovary indicating estrogenic effects of the compound. The endocrine-disrupting effects of triclosan were confirmed. The current results suggest that chronic exposure to triclosan altered reproductive endpoints thereby impairing normal reproductive functions in fish.

Temporal trends in exposure to parabens, benzophenones, triclosan, and triclocarban in adult females in Kyoto, Japan, from 1993 to 2016

Products used in daily life can contain chemicals such as parabens, benzophenones, triclosan, and triclocarban that have potential endocrine-disrupting effects. Little is known about the temporal trends of exposure levels to some of these chemicals in Japan. Our study assessed the intake and risk associated with exposure to commonly used chemicals. We measured the concentrations of five parabens, four benzophenones, and triclosan and triclocarban in 133 single spot urine samples. The urine samples were collected in 1993, 2000, 2003, 2009, 2011, and 2016 from healthy female residents in Kyoto, Japan. With the exception of methylparaben, ethylparaben, and butylparaben, there were no significant fluctuations in the concentrations of target chemicals over the study period; however, methylparaben, ethylparaben, and butylparaben showed temporal changes in concentrations. Methylparaben concentrations peaked in 2003 with a median value of 309 μg/g creatinine, ethylparaben concentrations peaked in 1993 with a median value of 17.3 μg/g creatinine, and butylparaben showed a decline, with the median values becoming non-detectable in 2009 and 2016. We calculated estimated daily intakes and hazard quotients for each chemical. In the analysis of total samples, 2.3% (3 samples) for butylparaben and 0.8% (1 sample) for propylparaben were found to surpass a hazard quotient of 1. Overall, 3% (n = 4) of the study participants exceeded a hazard index of 1. The potential health risks associated with exposure to butylparaben and propylparaben emphasize the need for further monitoring and research.

Reproductive endocrine disruption effect and mechanism in male zebrafish after life cycle exposure to environmental relevant triclosan

Triclosan (TCS) is a wide-spectrum antibacterial agent that is found in various water environments. It has been reported to have estrogenic effects. However, the impact of TCS exposure on the reproductive system of zebrafish (Danio rerio) throughout their life cycle is not well understood. In this study, zebrafish fertilized eggs were exposed to 0, 10, and 50 μg/L TCS for 120 days. The study investigated the effects of TCS exposure on brain and testis coefficients, the expression of genes related to the hypothalamus-pituitary-gonadal (HPG) axis, hormone levels, vitellogenin (VTG) content, histopathological sections, and performed RNA sequencing of male zebrafish. The results revealed that life cycle TCS exposure had significant effects on zebrafish reproductive parameters. It increased the testis coefficient, while decreasing the brain coefficient. TCS exposure also led to a decrease in mature spermatozoa and altered the expression of genes related to the HPG axis. Furthermore, TCS disrupted the balance of sex hormone levels and increased VTG content of male zebrafish. Transcriptome sequencing analysis indicated that TCS affected reproductive endocrine related pathways, including PPAR signaling pathway, cell cycle, GnRH signaling pathway, steroid biosynthesis, cytokine-cytokine receptor interaction, and steroid hormone biosynthesis. Protein-protein interaction (PPI) network analysis confirmed the enrichment of hub genes in these pathways, including bub1bb, ccnb1, cdc20, cdk1, mcm2, mcm5, mcm6, plk1, and ttk in the brain, as well as fabp1b.1, fabp2, fabp6, ccr7, cxcl11.8, hsd11b2, and hsd3b1 in the testis. This study sheds light on the reproductive endocrine-disrupting mechanisms of life cycle exposure to TCS.

Utility of zebrafish-based models in understanding molecular mechanisms of neurotoxicity mediated by the gut-brain axis

The gut microbes perform several beneficial functions which impact the periphery and central nervous systems of the host. Gut microbiota dysbiosis is acknowledged as a major contributor to the development of several neuropsychiatric and neurological disorders including bipolar disorder, depression, anxiety, Parkinson's disease, Alzheimer's disease, attention deficit hyperactivity disorder, and autism spectrum disorder. Thus, elucidation of how the gut microbiota-brain axis plays a role in health and disease conditions is a potential novel approach to prevent and treat brain disorders. The zebrafish (Danio rerio) is an invaluable vertebrate model that possesses conserved brain and intestinal features with those of humans, thus making zebrafish a valued model to investigate the interplay between the gut microbiota and host health. This chapter describes current findings on the utility of zebrafish in understanding molecular mechanisms of neurotoxicity mediated via the gut microbiota-brain axis. Specifically, it highlights the utility of zebrafish as a model organism for understanding how anthropogenic chemicals, pharmaceuticals and bacteria exposure affect animals and human health via the gut-brain axis.

Evolution of triclosan resistance modulates bacterial permissiveness to multidrug resistance plasmids and phages

The horizontal transfer of plasmids has been recognized as one of the key drivers for the worldwide spread of antimicrobial resistance (AMR) across bacterial pathogens. However, knowledge remain limited about the contribution made by environmental stress on the evolution of bacterial AMR by modulating horizontal acquisition of AMR plasmids and other mobile genetic elements. Here we combined experimental evolution, whole genome sequencing, reverse genetic engineering, and transcriptomics to examine if the evolution of chromosomal AMR to triclosan (TCS) disinfectant has correlated effects on modulating bacterial pathogen (Klebsiella pneumoniae) permissiveness to AMR plasmids and phage susceptibility. Herein, we show that TCS exposure increases the evolvability of K. pneumoniae to evolve TCS-resistant mutants (TRMs) by acquiring mutations and altered expression of several genes previously associated with TCS and antibiotic resistance. Notably, nsrR deletion increases conjugation permissiveness of K. pneumoniae to four AMR plasmids, and enhances susceptibility to various Klebsiella-specific phages through the downregulation of several bacterial defense systems and changes in membrane potential with altered reactive oxygen species response. Our findings suggest that unrestricted use of TCS disinfectant imposes a dual impact on bacterial antibiotic resistance by augmenting both chromosomally and horizontally acquired AMR mechanisms.

Uptake, tissue distribution, and biotransformation pattern of triclosan in tilapia exposed to environmentally-relevant concentrations

Although triclosan has been ubiquitously detected in aquatic environment and is known to have various adverse effects to fish, details on its uptake, bioconcentration, and elimination in fish tissues are still limited. This study investigated the uptake and elimination toxicokinetics, bioconcentration, and biotransformation potential of triclosan in Nile tilapia (Oreochromis niloticus) exposed to environmentally-relevant concentrations under semi-static regimes for 7 days. For toxicokinetics, triclosan reached a plateau concentration within 5-days of exposure, and decreased to stable concentration within 5 days of elimination. Approximately 50 % of triclosan was excreted by fish through feces, and up to 29 % of triclosan was excreted through the biliary excretion. For fish exposed to 200 ng·L-1, 2000 ng·L-1, and 20,000 ng·L-1, the bioconcentration factors (log BCFs) of triclosan in fish tissues obeyed similar order: bile ≈ intestine > gonad ≈ stomach > liver > kidney ≈ gill > skin ≈ plasma > brain > muscle. The log BCFs of triclosan in fish tissues are approximately maintained constants, no matter what triclosan concentrations in exposure water. Seven biotransformation products of triclosan, involved in both phase I and phase II metabolism, were identified in this study, which were produced through hydroxylation, bond cleavages, dichlorination, and sulfation pathways. Metabolite of triclosan-O-sulfate was detected in all tissues of tilapia, and more toxic product of 2,4-dichlorophenol was also found in intestine, gonad, and bile of tilapia. Meanwhile, two metabolites of 2,4-dichlorophenol-O-sulfate and monohydroxy-triclosan-O-sulfate were firstly discovered in the skin, liver, gill, intestine, gonad, and bile of tilapia in this study. These findings highlight the importance of considering triclosan biotransformation products in ecological assessment. They also provide a scientific basis for health risk evaluation of triclosan to humans, who are associated with dietary exposure through ingesting fish.

Toxic effects of triclosan in aquatic organisms: A review focusing on single and combined exposure of environmental conditions and pollutants

Triclosan (TCS) is an antibacterial agent commonly used in personal care products. Due to its widespread use and improper disposal, it is also a pervasive contaminant, particularly in aquatic environments. When released into water bodies, TCS can induce deleterious effects on developmental and physiological aspects of aquatic organisms and also interact with environmental stressors such as weather, metals, pharmaceuticals, and microplastics. Multiple studies have described the adverse effects of TCS on aquatic organisms, but few have reported on the interactions between TCS and other environmental conditions and pollutants. Because aquatic environments include a mix of contaminants and natural factors can correlate with contaminants, it is important to understand the toxicological outcomes of combinations of substances. Due to its lipophilic characteristics, TCS can interact with a wide range of substances and environmental stressors in aquatic environments. Here, we identify a need for caution when using TCS by describing not only the effects of exposure to TCS alone on aquatic organisms but also how toxicity changes when it acts in combination with multiple environmental stressors.

Antimicrobial cetylpyridinium chloride causes functional inhibition of mitochondria as potently as canonical mitotoxicants, nanostructural disruption of mitochondria, and mitochondrial Ca2+ efflux in living rodent and primary human cells

People are exposed to high concentrations of antibacterial agent cetylpyridinium chloride (CPC) via food and personal care products, despite little published information regarding CPC effects on eukaryotes. Here, we show that low-micromolar CPC exposure, which does not cause cell death, inhibits mitochondrial ATP production in primary human keratinocytes, mouse NIH-3T3 fibroblasts, and rat RBL-2H3 immune mast cells. ATP inhibition via CPC (EC50 1.7 μM) is nearly as potent as that caused by canonical mitotoxicant CCCP (EC50 1.2 μM). CPC inhibition of oxygen consumption rate (OCR) tracks with that of ATP: OCR is halved due to 1.75 μM CPC in RBL-2H3 cells and 1.25 μM in primary human keratinocytes. Mitochondrial [Ca2+] changes can cause mitochondrial dysfunction. Here we show that CPC causes mitochondrial Ca2+ efflux from mast cells via an ATP-inhibition mechanism. Using super-resolution microscopy (fluorescence photoactivation localization) in live cells, we have discovered that CPC causes mitochondrial nanostructural defects in live cells within 60 min, including the formation of spherical structures with donut-like cross section. This work reveals CPC as a mitotoxicant despite widespread use, highlighting the importance of further research into its toxicological safety.

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.

Toxic effects of triclosan on hepatic and intestinal lipid accumulation in zebrafish via regulation of m6A-RNA methylation

Triclosan (TCS), recognized as an endocrine disruptor, has raised significant concerns due to its widespread use and potential health risks. To explore the impact of TCS on lipid metabolism, both larval and adult zebrafish were subjected to acute and chronic exposure to TCS. Through analyzes of biochemical and physiological markers, as well as Oil Red O (ORO) and hematoxylin and eosin (H&E) staining, our investigation revealed that TCS exposure induced hepatic and intestinal lipid accumulation in larval and adult zebrafish, leading to structural damage and inflammatory responses in these tissues. The strong affinity of TCS with PPARγ and subsequent pathway activation indicate that PPARγ pathway plays a crucial role in TCS-induced lipid buildup. Furthermore, we observed a decrease in m6A-RNA methylation levels in the TCS-treated group, which attributed to the increased activity of the demethylase FTO and concurrent suppression of the methyltransferase METTL3 gene expression by TCS. The alteration in methylation dynamics is identified as a potential underlying mechanism behind TCS-induced lipid accumulation. To address this concern, we explored the impact of folic acid-a methyl donor for m6A-RNA methylation-on lipid accumulation in zebrafish. Remarkably, folic acid administration partially alleviated lipid accumulation by restoring m6A-RNA methylation. This restoration, in turn, contributed to a reduction in inflammatory damage observed in both the liver and intestines. Additionally, folic acid partially mitigates the up-regulation of PPARγ and related genes induced by TCS. These findings carry substantial implications for understanding the adverse effects of environmental pollutants such as TCS. They also emphasize the promising potential of folic acid as a therapeutic intervention to alleviate disturbances in lipid metabolism induced by environmental pollutants.

What Approaches Should be Used to Prioritize Pharmaceuticals and Personal Care Products for Research on Environmental and Human Health Exposure and Effects?

Pharmaceuticals and personal care products (PPCPs) are released from multiple anthropogenic sources and thus have a ubiquitous presence in the environment. The environmental exposure and potential effects of PPCPs on biota and humans has aroused concern within the scientific community and the public. Risk assessments are commonly conducted to evaluate the likelihood of chemicals including PPCPs that pose health threats to organisms inhabiting various environmental compartments and humans. Because thousands of PPCPs are currently used, it is impractical to assess the environmental risk of all of them due to data limitations; in addition, new PPCPs are continually being produced. Prioritization approaches, based either on exposure, hazard, or risk, provide a possible means by which those PPCPs that are likely to pose the greatest risk to the environment are identified, thereby enabling more effective allocation of resources in environmental monitoring programs in specific geographical locations and ecotoxicological investigations. In the present review, the importance and current knowledge concerning PPCP occurrence and risk are discussed and priorities for future research are proposed, in terms of PPCP exposure (e.g., optimization of exposure modeling in freshwater ecosystems and more monitoring of PPCPs in the marine environment) or hazard (e.g., differential risk of PPCPs to lower vs. higher trophic level species and risks to human health). Recommended research questions for the next 10 years are also provided, which can be answered by future studies on prioritization of PPCPs. Environ Toxicol Chem 2024;43:488-501. © 2022 SETAC.

Personal care products: an emerging threat to the marine bivalve Ruditapes philippinarum

In the last few decades, there has been a growing interest in understanding the behavior of personal care products (PCPs) in the aquatic environment. In this regard, the aim of this study is to estimate the accumulation and effects of four PCPs within the clam Ruditapes philippinarum. The PCPs selected were triclosan, OTNE, benzophenone-3, and octocrylene. A progressive uptake was observed and maximum concentrations in tissues were reached at the end of the exposure phase, up to levels of 0.68 µg g-1, 24 µg g-1, 0.81 µg g-1, and 1.52 µg g-1 for OTNE, BP-3, OC, and TCS, respectively. After the PCP post-exposure period, the removal percentages were higher than 65%. The estimated logarithm bioconcentration factor ranged from 3.34 to 2.93, in concordance with the lipophobicity of each substance. No lethal effects were found although significant changes were observed for ethoxyresorufin O-demethylase activity, glutathione S-transferase activity, lipid peroxidation, and DNA damage.

Interleukin 1β and interleukin 6 production in human immune cells is stimulated by the antibacterial compound Triclosan

Triclosan (TCS) is an antimicrobial compound widely used in personal hygiene products such as mouthwash and toothpaste; and has been found in human blood, breast milk, and urine. Interleukin (IL)-6 and IL-1 beta (IL-1β) are pro-inflammatory cytokines regulating cell growth, tissue repair, and immune function; increased levels of each have been associated with many diseases, including cancer. Previous studies showed that TCS at concentrations between 0.05 and 5 µM consistently increased the secretion of IL-1β and IL-6 from human immune cells within 24 h of exposure. The current study demonstrates that this increase in secretion was not due simply to release of existing stores but was due to an increase in cellular production/levels (both secreted and intracellular levels) of each of these cytokines. Production of IL-1β and IL-6 was increased by exposure to one or more concentration of TCS at each length of exposure (10 min, 30 min, 6 h, and 24 h). TCS-induced stimulation of cytokine production was shown to be dependent on the mitogen-activated protein kinase (MAPK) p44/42 (ERK 1/2). It was also shown that these TCS-induced increases in IL-1β and IL6 production were accompanied by increased mRNA for IL-1β and IL-6. The ability of TCS to increase production indicates that rather than activating a self-limiting process of depleting cells of already existing stores of IL-1β or IL-6, TCS can stimulate a process that has the capacity to provide sustained production of these cytokines and thus may lead to chronic inflammation and its pathological consequences.

Chronic administration of triclosan leads to liver fibrosis through hepcidin-ferroportin axis-mediated iron overload

Triclosan (TCS) has been manufactured as an antibacterial compound for half a century. Currently, it is widely used in various personal care products; however, its potential adverse effects raise a lot of attention. Here, we create a long-term oral administration mouse model and identify the corresponding hepatotoxicity of TCS. We discover that daily intragastric administration of 10 mg/kg TCS to mice for 12 weeks results in severe hepatic fibrosis. Further study displays that hepatic iron increased 18%, 23% and 29% upon oral TCS treatment for 4, 8 and 12 weeks, respectively. Accompanied by hepatic iron variation, splenic and duodenal iron are increased, which indicates systemic iron disorder. Not only excessive iron accumulated in the liver, abnormal hepatic malondialdehyde, prostaglandin synthase 2 and glutathione peroxidase 4 are pointed to ferroptosis. Additional study uncovers that hepcidin expression increases 7%, 10%, 4% in serum and 2.4-, 4.8-, and 2.3-fold on transcriptional levels upon TCS exposure for 4, 8 and 12 weeks, individually. Taken together, the mice in the TCS-treated group show disordered systemic iron homeostasis via the upregulated hepatic hepcidin-ferroportin axis. Meanwhile, both hepatic iron overload (systemic level) and hepatocyte ferroptosis (cellular level) are accused of TCS-induced liver fibrosis. Ferriprox®, an iron scavenger, significantly ameliorates TCS-induced liver fibrosis. In summary, this study confirms the impact of TCS on liver fibrosis; a critical signal pathway is also displayed. The significance of the current study is to prompt us to reevaluate the "pros and cons" of TCS applications.

Acute/chronic triclosan exposure induces downregulation of m6A-RNA methylation modification via mettl3 suppression and elicits developmental and immune toxicity to zebrafish

Triclosan (TCS), a prevalent contaminant in aquatic ecosystems, has been identified as a potential threat to both aquatic biota and human health. Despite its widespread presence, research into the immunotoxic effects of TCS on aquatic organisms is limited, and the underlying mechanisms driving these effects remain largely unexplored. Herein, we investigated the developmental and immune toxicities of environmentally relevant concentrations of TCS in zebrafish, characterized by morphological anomalies, histopathological impairments, and fluctuations in cytological differentiation and biomarkers following both acute (from 6 to 72/120 hpf) and chronic exposure periods (from 30 to 100 dpf). Specifically, acute exposure to TCS resulted in a significant increase in innate immune cells, contrasted by a marked decrease in T cells. Furthermore, we observed that TCS exposure elicited oxidative stress and a reduction in global m6A levels, alongside abnormal expressions within the m6A modification enzyme system in zebrafish larvae. Molecular docking studies suggested that mettl3 might be a target molecule for TCS interaction. Intriguingly, the knock-down of mettl3 mirrored the effects of TCS exposure, adversely impacting the growth and development of zebrafish, as well as the differentiation of innate immune cells. These results provide insights into the molecular basis of TCS-induced immunotoxicity through m6A-RNA epigenetic modification and aid in assessing its ecological risks, informing strategies for disease prevention linked to environmental contaminants.

Copper-zinc nanoparticle-decorated nitrogen-doped carbon composite for electrochemical determination of triclosan

A new sensor based on copper-zinc bimetal embedded and nitrogen-doped carbon-based composites (CuZn@NC) was prepared for triclosan (TCS) detection by pyrolyzing the precursor of Cu-Zn binuclear metal-organic framework (MOF). The performance for detecting TCS was evaluated using linear scanning voltammetry (LSV) and differential pulse voltammetry (DPV), and the proton and electron numbers during TCS oxidation have been proved to be one-to-one. The results indicated that CuZn@NC can present a satisfactory analysis performance for TCS detection. Under the optimized conditions, the linear response range was 0.2-600 µM and the detection limit was 47.9 nM. The sensor presented good stability (signal current dropped only 2.5% after 21 days) and good anti-interference of inorganic salts and small molecular organic acids. The good recovery (97.5-104.1%) for detecting spiked TCS in commercial products (toothpaste and hand sanitizer) suggested its potential for routine determination of TCS in real samples.

Deciphering the molecular mediators of triclosan-induced lipid accumulation: Intervention via short-chain fatty acids and miR-101a

As a potential environmental obesogen, triclosan (TCS) carries inherent risks of inducing obesity and metabolic disorders. However, the underlying molecular mechanisms behind the lipid metabolism disorder induced by TCS have remained elusive. Through a fusion of transcriptomics and microRNA target prediction, we hypothesize that miR-101a as a responsive miRNA to TCS exposure in zebrafish, playing a central role in disturbing lipid homeostasis. As an evidence, TCS exposure triggers a reduction in miR-10a expression that accompanied by elevation of genes linked to regulation of lipid homeostasis. Through precision-controlled interventions involving miRNA expression modulation, we discovered that inhibition of miR-101a enhanced expression of its target genes implicated in lipid homeostasis, subsequently triggering excessive fat accumulation. Meanwhile, the overexpression of miR-101a acts as a protective mechanism, counteracting the lipid metabolism disorder induced by TCS in the larvae. Notably, the combination of short-chain fatty acids (SCFAs) emerged as a potential remedy to alleviate TCS-induced lipid accumulation partially by counteracting the decline in miR-101a expression induced by TCS. These revelations provide insight into a prospective molecular framework underlying TCS-triggered lipid metabolism disorders, thereby paving the way for pre-emptive strategies in combating the ramifications of TCS pollution.

Early Developmental Exposure to Triclosan Impacts Fecal Microbial Populations, IgA and Functional Activities of the Rat Microbiome

Triclosan (TCS), a broad-spectrum antibacterial chemical, is detected in human urine, breast milk, amniotic fluid, and feces; however, little is known about its impact on the intestinal microbiome and host mucosal immunity during pregnancy and early development. Pregnant female rats were orally gavaged with TCS from gestation day (GD) 6 to postpartum (PP) day 28. Offspring were administered TCS from postnatal day (PND) 12 to 28. Studies were conducted to assess changes in the intestinal microbial population (16S-rRNA sequencing) and functional analysis of microbial genes in animals exposed to TCS during pregnancy (GD18), and at PP7, PP28 and PND28. Microbial abundance was compared with the amounts of TCS excreted in feces and IgA levels in feces. The results reveal that TCS decreases the abundance of Bacteroidetes and Firmicutes with a significant increase in Proteobacteria. At PND28, total Operational Taxonomic Units (OTUs) were higher in females and showed correlation with the levels of TCS and unbound IgA in feces. The significant increase in Proteobacteria in all TCS-treated rats along with the increased abundance in OTUs that belong to pathogenic bacterial communities could serve as a signature of TCS-induced dysbiosis. In conclusion, TCS can perturb the microbiome, the functional activities of the microbiome, and activate mucosal immunity during pregnancy and early development.

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.

Inhibitory Effects of Shikonin Dispersion, an Extract of Lithospermum erythrorhizon Encapsulated in β-1,3-1,6 Glucan, on Streptococcus mutans and Non-Mutans Streptococci

Shikonin is extracted from the roots of Lithospermum erythrorhizon, and shikonin extracts have been shown to have inhibitory effects on several bacteria. However, shikonin extracts are difficult to formulate because of their poor water solubility. In the present study, we prepared a shikonin dispersion, which was solubilized by the inclusion of β-1,3-1,6 glucan, and analysed the inhibitory effects of this dispersion on Streptococcus mutans and non-mutans streptococci. The shikonin dispersion showed pronounced anti-S. mutans activity, and inhibited growth of and biofilm formation by this bacterium. The shikonin dispersion also showed antimicrobial and antiproliferative effects against non-mutans streptococci. In addition, a clinical trial was conducted in which 20 subjects were asked to brush their teeth for 1 week using either shikonin dispersion-containing or non-containing toothpaste, respectively. The shikonin-containing toothpaste decreased the number of S. mutans in the oral cavity, while no such effect was observed after the use of the shikonin-free toothpaste. These results suggest that shikonin dispersion has an inhibitory effect on S. mutans and non-mutans streptococci, and toothpaste containing shikonin dispersion may be effective in preventing dental caries.

Endocrine disruptors: Unravelling the link between chemical exposure and Women's reproductive health

An Endocrine Disrupting Chemical (EDC) is any compound that disrupts the function of the endocrine system in humans and is ubiquitous in the environment either as a result of natural events or through anthropogenic activities. Bisphenol A, phthalates, parabens, pesticides, triclosan, polychlorinated biphenyls, and heavy metals, which are frequently found in the pharmaceutical, cosmetic, and packaging sectors, are some of the major sources of EDC pollutants. EDCs have been identified to have a deteriorating effect on the female reproductive system, as evidenced by the increasing number of reproductive disorders such as endometriosis, uterine fibroids, polycystic ovary syndrome, premature ovarian failure, menstrual irregularity, menarche, and infertility. Studying EDCs in relation to women's health is essential for understanding the complex interactions between environmental factors and health outcomes. It enables the development of strategies to mitigate risks, protect reproductive and overall health, and inform public policy decisions to safeguard women's well-being. Healthcare professionals must know the possible dangers of EDC exposure and ask about environmental exposures while evaluating patients. This may result in more precise diagnosis and personalized treatment regimens. This review summarises the existing understanding of prevalent EDCs that impact women's health and involvement in female reproductive dysfunction and underscores the need for more research. Further insights on potential mechanisms of action of EDCs on female has been emphasized in the article. We also discuss the role of nutritional intervention in reducing the effect of EDCs on women's reproductive health. EDC pollution can be further reduced by adhering to strict regulations prohibiting the release of estrogenic substances into the environment.

Exposure to biocides and its association with atopic dermatitis among children and adolescents: A population-based cross-sectional study in South Korea

BACKGROUND

Biocides have emerged as a contributor to the rising cases of atopic dermatitis among children and adolescents. Previous animal studies suggested that phenols, parabens, and pyrethroid insecticides present in these products might play a role in atopic dermatitis. However, there's limited epidemiological evidence confirming the individual or combined effects of exposure to these chemicals on atopic dermatitis in young populations. This study aimed to investigate the association between phenol, paraben, and pyrethroid metabolite levels in urine and atopic dermatitis among Korean children and adolescents METHODS: We analyzed 556 preschool children (3-5 years), 701 schoolchildren (6-11 years), and 731 adolescents (12-17 years) enrolled in the 4th Korean National Environmental Health Survey (KoNEHS) (2018-2020). We used logistic regression and Bayesian kernel machine regression to evaluate the association between atopic dermatitis and individual or mixed exposure to urinary triclosan (TCS), parabens (methylparaben, ethylparaben, propylparaben, and butylparaben), and 3-phenoxybenzoic acid (3-PBA) levels.

RESULTS

Urinary TCS levels were positively associated with atopic dermatitis in schoolchildren. When stratified by sex, male schoolchildren exhibited an increasing prevalence of atopic dermatitis as their urinary TCS and 3-PBA levels increased. The combined effect of biocide mixtures on atopic dermatitis was also significantly increased in male schoolchildren, with TCS as the main contributor.

CONCLUSIONS

These study findings suggest that biocides at levels found in Korean children and adolescents affect atopic dermatitis.

Triclosan induces earlier puberty onset in female mice via interfering with L-type calcium channels and activating Pik3cd

Triclosan (TCS) is a broad-spectrum antibacterial chemical widely presents in people's daily lives. Epidemiological studies have revealed that TCS exposure may affect female puberty development. However, the developmental toxicity after low-dose TCS continuous exposure remains to be confirmed. In our study, 8-week-old ICR female mice were continuously exposed to TCS (30, 300, 3000 μg/kg/day) or vehicle (corn oil) from 2 weeks before mating to postnatal day 21 (PND 21) of F1 female mice, while F1 female mice were treated with TCS intragastric administration from PND 22 until PND 56. Vaginal opening (VO) observation, hypothalamic-pituitary-ovarian (HPO) axis related hormones and genes detection, and ovarian transcriptome analysis were carried out to investigate the effects of TCS exposure on puberty onset. Meanwhile, human granulosa-like tumor cell lines (KGN cells) were exposed to TCS to further explore the biological mechanism of the ovary in vitro. The results showed that long-term exposure to low-dose TCS led to approximately a 3-day earlier puberty onset in F1 female mice. Moreover, TCS up-regulated the secretion of estradiol (E2) and the expression of ovarian steroidogenesis genes. Notably, ovarian transcriptomes analysis as well as bidirectional validation in KGN cells suggested that L-type calcium channels and Pik3cd were involved in TCS-induced up-regulation of ovarian-related hormones and genes. In conclusion, our study demonstrated that TCS interfered with L-type calcium channels and activated Pik3cd to up-regulate the expression of ovarian steroidogenesis and related genes, thereby inducing the earlier puberty onset in F1 female mice.

Chronic triclosan exposure induce impaired glucose tolerance by altering the gut microbiota

Triclosan (TCS) is an antimicrobial compound incorporated into more than 2000 consumer products. This compound is frequently detected in the human body and causes ubiquitous contamination in the environment, thereby raising concerns about its impact on human health and environmental pollution. Here, we demonstrated that 20 weeks' exposure of TCS drove the development of glucose intolerance by inducing compositional and functional alterations in intestinal microbiota in rats. Fecal-transplantation experiments corroborated the involvement of gut microbiota in TCS-induced glucose-tolerance impairment. 16S rRNA gene-sequencing analysis of cecal contents showed that TCS disrupted the gut microbiota composition in rats and increased the ratio of Firmicutes to Bacteroidetes. Cecal metabolomic analyses detected that TCS altered host metabolic pathways that are linked to host glucose and amino acid metabolism, particularly branched-chain amino acid (BCAA) biosynthesis. BCAA measurement confirmed the increase in serum BCAAs in rats exposed to TCS. Western blot and immunostaining results further confirmed that elevated BCAAs stimulated mTOR, a nutrient-sensing complex, and following IRS-1 serine phosphorylation, resulted in insulin resistance and glucose intolerance. These results suggested that TCS may induce glucose metabolism imbalance by regulating BCAA concentration by remodeling the gut microbiota.

Effects of triclosan exposure on stem cells from human exfoliated deciduous teeth (SHED) fate

Triclosan (TCS), a widely used broad-spectrum antibacterial agent and preservative, is commonly found in products and environments. Widespread human exposure to TCS has drawn increasing attention from researchers concerning its toxicological effect. However, minimal studies have focused on the impact of TCS exposure on human stem cells. Therefore, the aim of the present study was to evaluate the effects of TCS exposure on stem cells from human exfoliated deciduous teeth (SHED) and its molecular mechanisms. A series of experimental methods were conducted to assess cell viability, morphology, proliferation, differentiation, senescence, apoptosis, mitochondrial function, and oxidative stress after SHED exposure to TCS. Furthermore, transcriptome analysis was applied to investigate the response of SHED to different concentrations of TCS exposure and to explore the molecular mechanisms. We demonstrated that TCS has a dose-dependent proliferation and differentiation inhibition of SHED, while promoting cellular senescence, mitochondrial dysfunction, endoplasmic reticulum (ER) stress, and oxidative stress, as well as significantly induces apoptosis and autophagy flux inhibition at high concentrations. Interestingly, no significant morphological changes in SHED were observed after TCS exposure. Transcriptome analysis of normal and TCS-induced SHED suggested that SHED may use different strategies to counteract stress from different concentrations of TCS and showed significant differences. We discovered that TCS mediates cellular injury of SHED by enhancing the expression of PTEN, thereby inhibiting the phosphorylation levels of PI3K and AKT as well as mTOR expression. Collectively, our findings provide a new understanding of the toxic effects of TCS on human stem cell fate, which is important for determining the risk posed by TCS to human health.

Endocrine-disrupting chemicals and male reproductive health

Modifiable factors, such as environmental exposures, can impact human fertility. The objective of this review is to summarize the potential effects of exposure to important endocrine-disrupting chemicals on male reproductive health. Most experimental and animal data demonstrate strong evidence for the negative effects of exposure to phenols, phthalates, pesticides, and perfluoroalkyl and polyfluoroalkyl substances on male reproductive health. Although evidence of negative associations in humans was overall strong for phthalates and pesticides, limited and inconclusive relationships were found for the other examined chemical biomarkers. Reasons for the discrepancies in results include but are not limited to, differences in study populations, exposure concentrations, number of samples collected, sample sizes, study design, and residual confounding. Additional studies are needed, particularly for newer phenols and perfluoroalkyl and polyfluoroalkyl substances, given the scarce literature on the topic and increasing exposures over time.

Successive exposure to traditional disinfectants and quaternary ammonium compounds enhances resistance genes expression and co-selection in biofilm-based partial nitrification-anammox systems

Quaternary ammonium compounds (QACs) are recommended disinfectants with surfactant properties, surpassing triclosan (TCS) and chloroxylenol (PCMX). Given the transition from traditional disinfectants, it is essential to investigate their impacts on biological nitrogen removal systems and the fate of resistance genes (RGs). In this study, three biofilm-based partial nitrification-anammox (PN/A) systems were established. A reactor named PD was successively exposed to 1 mg/L PCMX and 3 mg/L dioctadecyldimethylammonium chloride (DODMAC, a common QACs). A reactor named TD was successively exposed to 1 mg/L TCS and 3 mg/L DODMAC. A reactor named CD served as a control with only 3 mg/L DODMAC exposure. Results indicated that the total nitrogen removal performance of CD deteriorated markedly with DODMAC exposure compared to that of PD and TD. This phenomenon correlated closely with variations in RGs and their co-selection patterns. Pre-exposure to PCMX or TCS increased the abundance of RGs in the extracellular DNA of the PN/A biofilm, but reduced RGs abundances in the extracellular DNA of water. The tolerance of the PN/A system to successive exposure to the two disinfectants may be strengthened through co-selection of QACs RGs (qacEdelta1-01, qacEdelta1-02, qacH-01 and qacH-02) and mobile genetic elements (intI1 and tnpA-04). Furthermore, potential hosts of RGs are crucial for maintaining PN/A performance. Accumulation of extracellular polymeric substances, reactive oxygen species, and lactate dehydrogenase plays vital roles in the accumulation and transmission of RGs within the PN/A system.

Toxicity of chemical-based hand sanitizers on children and the development of natural alternatives: a computational approach

The unintended exposure of children to hand sanitizers poses a high risk of potentially fatal complications. Skin irritation, dryness, cracking, peeling, hypoglycemia, apnea, and acidosis are examples of unintended consequences of hand sanitizer. The sanitizer reportedly kills normal microbial flora on hands, which usually promotes innate immunity among children under 12. Children are more susceptible to the toxicity associated with the chemical constituents of marketed chemical-based hand sanitizers; however, the studies to develop sanitizer formulations for children are rudimentary. The adverse events limit the use of hand sanitizers specifically in children because of their sensitive and delicate skin. Additionally, it is reported that many chemical-based hand sanitizer formulations, especially alcohol-based ones may also contain contaminants like methanol, acetaldehyde, benzene, isopropanol, and ethyl-acetate. These contaminants are found to be hazardous to human health exhibiting toxicity on ingestion, inhalation, or dermal exposure, especially in children. Therefore, it is important to design novel, innovative, safer sanitizer formulations for children. The study aims to discuss the toxic contaminants in chemical-based sanitizer formulations and propose a design for novel herbal formulations with minimal toxicity and adverse effects, especially for children. The review focuses on ADMET analysis of the common contaminants in hand sanitizers, molecular docking, Lipinski's rule of five analysis, and molecular simulation studies to analyze the efficacy of interaction with the receptor leading to anti-microbial activity and drug-likeness of the compound. The in silico methods can effectively validate the potential efficacy of novel formulations of hand sanitizers designed for children as an efficient alternative to chemical-based sanitizers with greater efficacy and the absence of toxic contaminants.