Effect of triclosan (TRN) on energy-linked functions of rat liver mitochondria

Triclocarban and triclosan promote breast cancer progression in vitro and in vivo via activating G protein-coupled estrogen receptor signaling pathways

Triclocarban (TCC) and triclosan (TCS) have been detected ubiquitously in human body and evoked increasing concerns. This study aimed to reveal the induction risks of TCC and TCS on triple negative breast cancer through non-genomic GPER-mediated signaling pathways. Molecular simulation indicated that TCC exhibited higher GPER binding affinity than TCS theoretically. Calcium mobilization assay displayed that TCC/TCS activated GPER signaling pathway with the lowest observed effective concentrations (LOEC) of 10 nM/100 nM. TCC and TCS also upregulated MMP-2/9, EGFR, MAPK3 but downregulated MAPK8 via GPER-mediated signaling pathway. Proliferation assay showed that TCC/TCS induced 4 T1 breast cancer cells proliferation with the LOEC of 100 nM/1000 nM. Wound-healing and transwell assays showed that TCC/TCS promoted 4 T1 cells migration in a concentration-dependent manner with the LOEC of 10 nM. The effects of TCC on breast cancer cells proliferation and migration were stronger than TCS and both were regulated by GPER. TCC/TCS induced migratory effects were more significantly than proliferative effect. Mechanism study showed that TCC/TCS downregulated the expression of epithelial marker (E-cadherin) but upregulated mesenchymal markers (snail and N-cadherin), which was reversed by GPER inhibitor G15. These biomarkers results indicated that TCC/TCS-induced 4 T1 cells migration was a classic epithelial to mesenchymal transition mechanism regulated by GPER signaling pathway. Orthotopic tumor model verified that TCC promoted breast cancer in-situ tumor growth and distal tissue metastasis via GPER-mediated signaling pathway at human-exposure level of 10 mg/kg/d. TCC-induced tissue metastasis of breast cancer was more significantly than in-situ tumor growth. Overall, we demonstrated for the first time that TCC/TCS could activate the GPER signaling pathways to induce breast cancer progression.

The potential ecological risk of veterinary pharmaceuticals from swine wastewater on freshwater aquatic environment

The impact of pharmaceutical residue transport in the aquatic ecosystem has become an increasing subject of environmental interest due to the inherent bioactivity of trace levels of antibiotics and the negative environmental and public health impact. In this study, three veterinary pharmaceuticals including tetracycline, ivermectin, and salicylic acid were investigated in a piggery effluent from Western Cape, South Africa. Three freshwater organisms' taxonomic groups (Pseudokirchneriella subcapitata, Daphnia magna, and Tetrahymena thermophila) were used to determine the ecological risk of different treated piggery effluent concentration range of 1%, 10%, and 20% and a cocktail mixture of veterinary pharmaceuticals of environmental concerns. The average concentration of veterinary pharmaceuticals was in the range of 47.35, 7.19, and 1.46 μg L^-1 for salicylic acid, chloro-tetracycline, and ivermectin, respectively. P. subcapitata exposed to 20% piggery wastewater effluent at 24- and 48-h EC₅₀ showed a toxicity value of 14.2% and 13.6% (v/v), respectively. The study established the ecological risk of the test compounds as low to medium risk for low-level dose and low concentrations of piggery effluent. The relative sensitivity ranking of the taxa drawn is microalgae > protozoa > Cladocera. The study results demonstrated that a high dose of piggery effluent and mixtures of veterinary pharmaceutical can pose a high risk in freshwater ecosystems. PRACTITIONER POINTS: Transport processes of veterinary antibiotics into the environment were investigated. Dilution effect of the veterinary pharmaceutical on the antibiotic levels exists. High dose of piggery effluent presented an ecological risk.

Antibiotic resistance in the aquatic environment: Analytical techniques and interactive impact of emerging contaminants

Antibiotic pollution is becoming an increasingly severe threat globally. Antibiotics have emerged as a new class of environmental pollutants due to their expanding usage and indiscriminate application in animal husbandry as growth boosters. Contamination of aquatic ecosystems by antibiotics can have a variety of negative impacts on the microbial flora of these water bodies, as well as lead to the development and spread of antibiotic-resistant genes. Various strategies for removing antibiotics from aqueous systems and environments have been developed. Many of these approaches, however, are constrained by their high operating costs and the generation of secondary pollutants. This review aims to summarize research on the distribution and effects of antibiotics in aquatic environments, their interaction with other emerging contaminants, and their remediation strategy. The ecological risks associated with antibiotics in aquatic ecosystems and the need for more effective monitoring and detection system are also highlighted.

Comparative Histological Study on the Effect of Tramadol Abuse on the Testis of Juvenile and Adult Male Albino Mice

As a synthetic analog of codeine, tramadol is often prescribed to treat mild to moderate pains. This study was designed to estimate and compare the histological effect of tramadol on testes of both juvenile and adult male albino mice. A total number of 40 healthy male albino mice were classified into two main groups as follows: group I (juvenile group, includes 20 mice aged three weeks) subdivided equally into group Ia (control group received isotonic saline) and group Ib (tramadol-treated group received 40 mg/kg/d tramadol orally for 30 days); group II (adult group, includes 20 mice aged two months) subdivided equally into group IIa (control group received isotonic saline) and group IIb (tramadol-treated group). Juvenile and adult tramadol-treated groups showed numerous testicular changes, including blood vessels congestion, widening of intercellular spaces, vacuolization in interstitial tissues, luminal germ cells exfoliation, and increased expression of caspase-3 that indicated cellular apoptosis. In the ultrastructural examination, spermatogenic cells degenerated with the frequent appearance of apoptotic cells. Sertoli cells showed vacuolations, large lipid droplets, and disrupted intercellular cell junctions. These observed testicular changes were markedly observed in the juvenile group. Testicular abnormalities and apoptotic changes can be caused by tramadol administration. These abnormalities are more common in juvenile mice.

An in vivo study of the toxic effects of triclosan on Xenopus laevis (Daudin, 1802) frog: Assessment of viability, tissue damage and mitochondrial dysfunction

The present study describes the in vivo effect of triclosan on the frog Xenopus laevis (Daudin, 1802). We have found a dose-dependence of the effect of triclosan on the survival of frogs. At a dose of 2 mg/L, the death of frogs was observed already on the 4th day of the experiment, while at a concentration of 0.5 mg/L, the frogs remained viable for 11 days. Triclosan caused damage to the liver tissue, which was expressed in an increase in the area of hemorrhage and the number of melanomacrophage centers. 0.5 mg/L of this agent did not affect the number of frog red blood cells, but reduced their osmotic resistance. Keeping animals in water containing triclosan (0.5 mg/L for 96 h) led to the suppression of the state 3 respiration rate of frog liver mitochondria. This effect was accompanied by suppression of the combined activity of complexes II and III of the mitochondrial respiratory chain. In parallel with this, we observed a reduction in the Ca²⁺ retention capacity of frog liver mitochondria, indicating a decrease in the resistance of organelles to mitochondrial permeability transition pore opening. The paper discusses the effects of triclosan on aquatic organisms.

Non-destructive biomarkers can reveal effects of the association of microplastics and pharmaceuticals or personal care products

Methods to assess the effects of contaminants on marine organisms typically involve euthanasia to obtain samples, but less invasive techniques may be more appropriate for working with threatened species. In this study, were assessed the biological responses of crabs exposed to microplastics and contaminants of emerging concern. Biochemical and cellular effects (lipid peroxidation, DNA damage, cholinesterase activity, and lysosomal membrane stability) in hemolymph were analyzed in a kinetic study, at 3 and 7 days, in U. cordatus exposed to microplastics spiked with Triclosan (TCS) or 17α-Ethynylestradiol (EE2). The results showed that the contaminants were produced toxic effects in the crabs exposed either to the microplastics alone (oxidative stress, genotoxicity, and neurotoxicity), or to microplastics with TCS or EE2 adsorbed (neurotoxic and cytotoxic). The present study showed the responsiveness of non-lethal analyzes to understanding the biological effects of combined exposure to microplastics and chemical pollution.

Mitochondria-affecting small molecules ameliorate proteostasis defects associated with neurodegenerative diseases

Macroautophagic recycling of dysfunctional mitochondria, known as mitophagy, is essential for mitochondrial homeostasis and cell viability. Accumulation of defective mitochondria and impaired mitophagy have been widely implicated in many neurodegenerative diseases, and loss-of-function mutations of PINK1 and Parkin, two key regulators of mitophagy, are amongst the most common causes of heritable parkinsonism. This has led to the hypothesis that pharmacological stimulation of mitophagy may be a feasible approach to combat neurodegeneration. Toward this end, we screened ~ 45,000 small molecules using a high-throughput, whole-organism, phenotypic screen that monitored accumulation of PINK-1 protein, a key event in mitophagic activation, in a Caenorhabditis elegans strain carrying a Ppink-1::PINK-1::GFP reporter. We obtained eight hits that increased mitochondrial fragmentation and autophagosome formation. Several of the compounds also reduced ATP production, oxygen consumption, mitochondrial mass, and/or mitochondrial membrane potential. Importantly, we found that treatment with two compounds, which we named PS83 and PS106 (more commonly known as sertraline) reduced neurodegenerative disease phenotypes, including delaying paralysis in a C. elegans β-amyloid aggregation model in a PINK-1-dependent manner. This report presents a promising step toward the identification of compounds that will stimulate mitochondrial turnover.

Ecotoxicogenomic analysis of zebrafish embryos exposed to triclosan and mixture triclosan and methyl triclosan using suppression subtractive hybridization and next-generation sequencing

Triclosan (TCS) and methyl-triclosan (MTCS), an environmental transformation product of biocide of TCS, have been detected in water, sediment, fish, and invertebrates. In this study, the key pathway perturbation in zebrafish (Danio rerio) embryos exposed to TCS (300 μg/L) and TCS/MTCS mixture (300 μg/L TCS + 30 μg/L MTCS) was assessed by integrating the metabolomic and transcriptomic dysregulation. The differential expressed genes (DEGs) were obtained from the subtracted cDNA libraries by using the suppression subtractive hybridization and next-generation sequencing approach. The dysregulation of twenty-eight GO terms and four KEGG pathways, including oxidative phosphorylation and cardiac muscle contraction, were shown in the TCS treatment group, indicating that TCS could disrupt the mitochondrial inner membrane function by downshifting the electrochemical gradient. Meanwhile, the addition of MTCS in the exposure would cause fourteen additional significant KEGG pathway changes, demonstrating the different effects between two exposure. A pathway-based analysis using the identified DEGs and the altered metabolites in zebrafish embryos treated with TCS and TCS/MTCS mixture, collectively, has been applied. This study demonstrated that the integration of SSH-NGS and metabolomics could reveal toxic effects and potential diseases associated with the exposures of TCS and MTCS in aquatic environments.

ABC proteins activity and cytotoxicity in zebrafish hepatocytes exposed to triclosan

Chemicals such as triclosan are a concern because of their presence on daily products (soap, deodorant, hand sanitizers …), consequently this compound has an ubiquitous presence in the environment. Little is known about the effect of this bactericide on aquatic life. The aim of this study is to analyze triclosan exposure (24 h) to an in vitro model, zebrafish hepatocytes cell line (ZF-L), if it can be cytotoxic (mitochondrial activity, membrane stability and apoptosis) and if can activate ATP-binding cassette (ABC) proteins (activity, expression and protein/compound affinity). Triclosan was cytotoxic to hepatocytes when exposed to concentrations (1-4 mg/L). The results showed impaired mitochondria function, as well, plasma membrane rupture and an increase of apoptotic cells. We observed an ABC proteins activity inhibition in cells exposed to 0.5 and 1 mg/L. When ABCBs and ABCC2 proteins expression were analyzed, there was an increase of protein expression in both ABC proteins families on cells exposed to 1 mg/L of triclosan. On molecular docking results, triclosan and the fluorescent used as substrate (rhodamine) presented high affinity with all ABC proteins family tested, showing a greater affinity with ABCC2. In conclusion, this study showed that triclosan can be cytotoxic to ZF-L. Molecular docking indicated high affinity between triclosan and the tested pumps.

Increased apoptosis, reduced Wnt/β-catenin signaling, and altered tail development in zebrafish embryos exposed to a human-relevant chemical mixture

A wide variety of anthropogenic chemicals is detected in humans and wildlife and the health effects of various chemical exposures are not well understood. Early life stages are generally the most susceptible to chemical disruption and developmental exposure can cause disease in adulthood, but the mechanistic understanding of such effects is poor. Within the EU project EDC-MixRisk, a chemical mixture (Mixture G) was identified in the Swedish pregnancy cohort SELMA by the inverse association between levels in women at around gestational week ten with birth weight of their children. This mixture was composed of mono-ethyl phthalate, mono-butyl phthalate, mono-benzyl phthalate, mono-ethylhexyl phthalate, mono-isononyl phthalate, triclosan, perfluorohexane sulfonate, perfluorooctanoic acid, and perfluorooctane sulfonate. In a series of experimental studies, we characterized effects of Mixture G on early development in zebrafish models. Here, we studied apoptosis and Wnt/β-catenin signaling which are two evolutionarily conserved signaling pathways of crucial importance during development. We determined effects on apoptosis by measuring TUNEL staining, caspase-3 activity, and acridine orange staining in wildtype zebrafish embryos, while Wnt/β-catenin signaling was assayed using a transgenic line expressing an EGFP reporter at β-catenin-regulated promoters. We found that Mixture G increased apoptosis, suppressed Wnt/β-catenin signaling in the caudal fin, and altered the shape of the caudal fin at water concentrations only 20-100 times higher than the geometric mean serum concentration in the human cohort. These findings call for awareness that pollutant mixtures like mixture G may interfere with a variety of developmental processes, possibly resulting in adverse health effects.

Exploring the biophysicochemical alteration of green alga Asterococcus superbus interactively affected by nanoparticles, triclosan and illumination

Toxic effects on Asterococcus superbus were studied based on different combinations of P25-TiO₂, nano-ZnO and triclosan under multiple illumination conditions. A full factorial design (2 × 2×2 × 3) was implemented to explore interactive effects, and to identify significant factors. The results showed illumination is the most important factor with significance and becomes one of the main reasons to affect chlorophyll pigments, photosynthesis activity, unsaturated fatty acids, mitochondria function, and cause oxidative stress. Triclosan considerably affects cell viability, photosynthesis activity, lipid peroxidation and protein structure, for which triclosan is more significant than nano-ZnO. P25 is significant for oxidative stress, antioxidant enzyme, and lipid peroxidation. P25 * nano-ZnO is the only significant interaction of pollutants, affecting macromolecules, lipid peroxidation, and photosynthesis activity. High-order interactions play significant roles in affecting multiple molecular components. Two groups of endpoints are best to reflect alga responses to interactively effects from P25, nano-ZnO, and triclosan. One is ROS, chlorophyll pigments, TBARS, area, MTT, and MMP, and the other one is chlorophyll pigments, ROS, TBARS, CAT, MTT and SOD. Our findings can be instructive for a comprehensive comparison among interactions of multiple pollutants and environmental factors in natural waters, such that more robust environmental toxicity analyses can be performed.

Triclosan changes community composition and selects for specific bacterial taxa in marine periphyton biofilms in low nanomolar concentrations

The antibacterial agent Triclosan (TCS) is a ubiquitous environmental contaminant due to its widespread use. Sensitivity to TCS varies substantially among eu- and pro-karyotic species and its risk for the marine environment remains to be better elucidated. In particular, the effects that TCS causes on marine microbial communities are largely unknown. In this study we therefore used 16S amplicon rDNA sequencing to investigate TCS effects on the bacterial composition in marine periphyton communities that developed under long-term exposure to different TCS concentrations. Exposure to TCS resulted in clear changes in bacterial composition already at concentrations of 1 to 3.16 nM. We conclude that TCS affects the structure of the bacterial part of periphyton communities at concentrations that actually occur in the marine environment. Sensitive taxa, whose abundance decreased significantly with increasing TCS concentrations, include the Rhodobiaceae and Rhodobacteraceae families of Alphaproteobacteria, and unidentified members of the Candidate division Parcubacteria. Tolerant taxa, whose abundance increased significantly with higher TCS concentrations, include the families Erythrobacteraceae (Alphaproteobacteria), Flavobacteriaceae (Bacteroidetes), Bdellovibrionaceae (Deltaproteobacteria), several families of Gammaproteobacteria, and members of the Candidate phylum Gracilibacteria. Our results demonstrate the variability of TCS sensitivity among bacteria, and that TCS can change marine bacterial composition at concentrations that have been detected in the marine environment.

Effects of Microplastics Associated with Triclosan on the Oyster Crassostrea brasiliana: An Integrated Biomarker Approach

Urban waste is a complex mixture of different substances, including microplastics and pharmaceuticals and personal care products. Microplastics have a high affinity for hydrophobic substances. One of these substances is triclosan, a bactericide used in a variety of hygiene products. Therefore, microplastics (MPs) may serve as a vector between triclosan and aquatic organisms. The current study sought to evaluate the effects of the interaction between microplastics and triclosan based on a mechanistic approach in which the oyster Crassostrea brasiliana was used as a model. The organisms were exposed to three conditions: the control, microplastic (MP), and microplastic contaminated with triclosan (MPT). The organisms were exposed for 3 or 7 days. After the exposure time, hemolymph was sampled for performing the neutral red retention time assay and, subsequently, the gills, digestive glands, and adductor muscles were dissected for measuring biomarkers responses (EROD, DBF, GST, GPx, GSH, lipid peroxidation, DNA strand breaks, and AChE). Our results demonstrate combined effects of MPs associated with triclosan on oyster physiology and biochemistry, as well as on lysosomal membrane stability. These results contribute to understanding the effects of contaminants of emerging concern and microplastics on aquatic organisms.

Industrial, Biocide, and Cosmetic Chemical Inducers of Cholestasis

A frequent side effect of many drugs includes the occurrence of cholestatic liver toxicity. Over the past couple of decades, drug-induced cholestasis has gained considerable attention, resulting in a plethora of data regarding its prevalence and mechanistic basis. Likewise, several food additives and dietary supplements have been reported to cause cholestatic liver insults in the past few years. The induction of cholestatic hepatotoxicity by other types of chemicals, in particular synthetic compounds, such as industrial chemicals, biocides, and cosmetic ingredients, has been much less documented. Such information can be found in occasional clinical case reports of accidental intake or suicide attempts as well as in basic and translational study reports on mechanisms or testing of new therapeutics in cholestatic animal models. This paper focuses on such nonpharmaceutical and nondietary synthetic chemical inducers of cholestatic liver injury, in particular alpha-naphthylisocyanate, 3,5-diethoxycarbonyl-1,4-dihydrocollidine, methylenedianiline, paraquat, tartrazine, triclosan, 2-octynoic acid, and 2-nonynoic acid. Most of these cholestatic compounds act by similar mechanisms. This could open perspectives for the prediction of cholestatic potential of chemicals.

Integration of Metabolomics and Lipidomics Reveals Metabolic Mechanisms of Triclosan-Induced Toxicity in Human Hepatocytes

Triclosan (TCS), an extensively used antimicrobial agent, has raised considerable concern due to its hepatocarcinogenic potential. However, previous hepatotoxicity studies primarily focused on the activation of specific intracellular receptors, the underlying mechanisms still warrant further investigation at the metabolic level. Herein, we applied metabolomics in combination with lipidomics to unveil TCS-related metabolic responses in human normal and cancerous hepatocytes. Endogenous and exogenous metabolites were analyzed for the identification of metabolic biomarkers and biotransformation products. In L02 normal cells, TCS exposure induced the up-regulation of purine metabolism and amino acid metabolism, caused lipid accumulation, and disturbed energy metabolism. These metabolic disorders in turn enhanced the overproduction of reactive oxygen species (ROS), leading to the alteration of antioxidant enzyme activities, down-regulation of endogenous antioxidants, and peroxidation of lipids. TCS-induced oxidative stress is thus considered to be one crucial factor for hepatotoxicity. However, in HepG2 cancer cells, TCS underwent fast detoxification through phase II metabolism, accompanied by the enhancement of energy metabolism and elevation of antioxidant defense system, which contributed to the potential effects of TCS on human hepatocellular carcinoma development. These different responses of metabolism between normal and cancerous hepatocytes provide novel and robust perspectives for revealing the mechanisms of TCS-triggered hepatotoxicity.

QSAR for baseline toxicity and classification of specific modes of action of ionizable organic chemicals in the zebrafish embryo toxicity test

The fish embryo toxicity (FET) test with the zebrafish Danio rerio is widely used to assess the acute toxicity of chemicals thereby serving as animal alternative to the acute fish toxicity test. The minimal toxicity of neutral chemicals in the FET can be predicted with a previously published Quantitative Structure-Activity Relationship (QSAR) based on the liposome-water partition coefficient K_lipw. Such a QSAR may serve to plan toxicity testing and to evaluate whether an observed effect is caused by a specific mode of action (MoA). The applicability domain of this QSAR was extended to ionizable organic chemicals (IOC) without any modification of slope and intercept simply by replacing the K_lipw with the speciation-corrected liposome-water distribution ratio (D_lipw(pH)) as descriptor for the uptake into the embryo. FET LC₅₀ values of IOCs were extracted from an existing FET database and published literature. IOCs were selected that are present concomitantly as neutral and charged, species, i.e., acids with an acidity constant pK_a <10 and bases with pK_a>5. IOCs were grouped according to their putative MoA of acute aquatic toxicity. The toxic ratios (TR) in the FET were derived by of the experimental FET-LC₅₀ in comparison with the baseline toxicity QSAR. Baseline toxicants were confirmed to align well with the FET baseline toxicity QSAR (TR < 10). Chemicals identified to act as specific or reactive chemicals with the toxic ratio analysis in the FET test (TR > 10) were generally consistent with MoA classification for acute fish toxicity with a few exceptions that were suspected to have had issues with the stability of the pH during testing. One critical aspect for the effect analysis of ionizable chemicals is the pH, since the difference between pH and pK_a determines the speciation and thereby the D_lipw(pH).

Biocide triclosan impairs byssus formation in marine mussels Mytilus galloprovincialis

The effects of the biocide Triclosan, used in personal care products and known as a common environmental contaminant, on byssal apparatus were studied in the marine mussel Mytilus galloprovincialis. Experimental evidences indicated that an exposure for 7 days at a concentration of 10 μg/L induced marked alterations in the byssus gland resulting in a significant delay in byssus regrowth and in a decrease in threads resistance to traction. Such alterations in animals exposed to tidal and waves action would cause a significant loss in ecological fitness and severely impact on mussel survival. Triclosan release in coastal environments therefore should be more carefully monitored to prevent drastic consequences.

Antimicrobial agent triclosan disrupts mitochondrial structure, revealed by super-resolution microscopy, and inhibits mast cell signaling via calcium modulation

The antimicrobial agent triclosan (TCS) is used in products such as toothpaste and surgical soaps and is readily absorbed into oral mucosa and human skin. These and many other tissues contain mast cells, which are involved in numerous physiologies and diseases. Mast cells release chemical mediators through a process termed degranulation, which is inhibited by TCS. Investigation into the underlying mechanisms led to the finding that TCS is a mitochondrial uncoupler at non-cytotoxic, low-micromolar doses in several cell types and live zebrafish. Our aim was to determine the mechanisms underlying TCS disruption of mitochondrial function and of mast cell signaling. We combined super-resolution (fluorescence photoactivation localization) microscopy and multiple fluorescence-based assays to detail triclosan's effects in living mast cells, fibroblasts, and primary human keratinocytes. TCS disrupts mitochondrial nanostructure, causing mitochondria to undergo fission and to form a toroidal, "donut" shape. TCS increases reactive oxygen species production, decreases mitochondrial membrane potential, and disrupts ER and mitochondrial Ca²⁺ levels, processes that cause mitochondrial fission. TCS is 60 × more potent than the banned uncoupler 2,4-dinitrophenol. TCS inhibits mast cell degranulation by decreasing mitochondrial membrane potential, disrupting microtubule polymerization, and inhibiting mitochondrial translocation, which reduces Ca²⁺ influx into the cell. Our findings provide mechanisms for both triclosan's inhibition of mast cell signaling and its universal disruption of mitochondria. These mechanisms provide partial explanations for triclosan's adverse effects on human reproduction, immunology, and development. This study is the first to utilize super-resolution microscopy in the field of toxicology.

In Vitro Evaluation of Mitochondrial Function and Estrogen Signaling in Cell Lines Exposed to the Antiseptic Cetylpyridinium Chloride

BACKGROUND

Quaternary ammonium salts (QUATS), such as cetylpyridinium chloride (CPC) and benzalkonium chloride (BAK), are frequently used in antiseptic formulations, including toothpastes, mouthwashes, lozenges, throat and nasal sprays, and as biocides. Although in a recent ruling, the U.S. Food and Drug Administration (FDA) banned CPC from certain products and requested more data on BAK's efficacy and safety profile, QUATS, in general, and CPC and BAK, in particular, continue to be used in personal health care, food, and pharmaceutical and cleaning industries.

OBJECTIVES

We aimed to assess CPC's effects on mitochondrial toxicity and endocrine disruption in vitro.

METHOD

Mitochondrial O₂ consumption and adenosine triphosphate (ATP) synthesis rates of osteosarcoma cybrid cells were measured before and after CPC and BAK treatment. Antiestrogenic effects of the compounds were measured by a luciferase-based assay using recombinant human breast carcinoma cells (VM7Luc4E2, ERalpha-positive).

RESULTS

CPC inhibited both mitochondrial O₂ consumption [half maximal inhibitory concentration (IC₅₀): 3.8μM] and ATP synthesis (IC₅₀: 0.9μM), and additional findings supported inhibition of mitochondrial complex 1 as the underlying mechanism for these effects. In addition, CPC showed concentration-dependent antiestrogenic activity half maximal effective concentration [(EC₅₀): 4.5μM)]. BAK, another antimicrobial QUATS that is structurally similar to CPC, and the pesticide rotenone, a known complex 1 inhibitor, also showed mitochondrial inhibitory and antiestrogenic effects. In all three cases, there was overlap of the antiestrogenic activity with the mitochondrial inhibitory activity.

CONCLUSIONS

Mitochondrial inhibition in vitro occurred at a CPC concentration that may be relevant to human exposures. The antiestrogenic activity of CPC, BAK, rotenone, and triclosan may be related to their mitochondrial inhibitory activity. Our findings support the need for additional research on the mitochondrial inhibitory and antiestrogenic effects of QUATS, including CPC and BAK. https://doi.org/10.1289/EHP1404.

Effects of triclosan (TCS) on fecundity, the antioxidant system, and oxidative stress-mediated gene expression in the copepod Tigriopus japonicus

Triclosan (TCS) is an antimicrobial agent that has been widely dispersed and detected in the marine environment. However, the effects of TCS in marine invertebrates are poorly understood. In this study, the effects of TCS on life cycle history (e.g. mortality and fecundity) along with cellular reactive oxygen species (ROS) levels, GSH content, antioxidant enzymatic activities, and mRNA expression levels of oxidative stress-mediated genes were measured in the copepod Tigriopus japonicus. The no observed effect concentration (NOEC) and median lethal concentration (LC50) of TCS in the adult stage were determined to be 300μg/L and 437.476μg/L, respectively, while in the nauplius stages the corresponding values were 20μg/L, and 51.76μg/L, respectively. Fecundity was significantly reduced (P<0.05) in response to TCS at 100μg/L. Concentration- and time-dependent analysis of ROS, GSH content (%), and antioxidant enzymatic activities (e.g. GST, GPx, and SOD) were significantly increased (P<0.05) in response to TCS exposure. Additionally, mRNA expression of detoxification (e.g., CYPs) and antioxidant (e.g., glutathione S-transferase-sigma isoforms, Cu/Zn superoxide dismutase, catalase) genes was modulated in response to TCS exposure at different concentrations over a 24h period. Our results revealed that TCS can induce reduced fecundity and oxidative stress with transcriptional regulation of oxidative stress-mediated genes with activation of the antioxidant system in the copepod T. japonicus.

Baseline toxicity and ion-trapping models to describe the pH-dependence of bacterial toxicity of pharmaceuticals

In numerous studies on the toxicity of ionisable organic chemicals, it has been shown that the toxicity was typically higher, when larger fractions of the neutral species were present. This observation was explained in some cases by slower uptake of charged species. In other cases it was suggested that the neutral species has intrinsically higher toxicity than the charged species or is alone responsible for the toxicity. However, even permanently charged and organic chemicals with multiple acid and base functional groups and zwitterions are toxic. We set out to reconcile the divergent views and to compare the various existing models for describing the pH-dependence of toxicity with the goal to derive one model that is valid independent of the type and number of charges on the molecule. To achieve this goal we measured the cytotoxicity of 18 acidic, 15 basic and 9 multiprotic/zwitterionic pharmaceuticals at pH 5.5 to pH 9 with the bioluminescence inhibition test using Aliivibrio fischeri (Microtox assay). This assay is useful for an evaluation of various models to describe pH-dependent toxicity because the majority of chemicals act as baseline toxicants in this 30 min cytotoxicity assay. Therefore baseline toxicity with constant membrane concentrations of the sum of all chemical species of approximately 200 mmol kg_lip^-1 served for the validation of the suitability of the various tested models. We confirmed that most tested pharmaceuticals acted as baseline toxicants in this assay at all examined pH values, when toxicity was modeled with a mixture model of concentration addition between the neutral species and all charged species. An ion trapping model, that assumes that the membrane permeability of charged species is kinetically limited, improved model predictions for some pharmaceuticals and pH values. However, neither unhindered uptake nor no uptake of the charged species were ideal models; the reality lies presumably between the two limiting cases with a slower uptake of the charged species than the neutral species. For practical applications a previously developed QSAR model with the ionisation-corrected liposome-water distribution ratio as the sole physicochemical descriptor proved to be generally applicable for all ionisable organic chemicals including those with multiple charges and zwitterions.

Triclosan alterations of estuarine phytoplankton community structure

Antimicrobial additives in pharmaceutical and personal care products are a major environmental concern due to their potential ecological impacts on aquatic ecosystems. Triclosan (TCS) has been used as an antiseptic, disinfectant, and preservative in various media. The sublethal and lethal effects of TCS on estuarine phytoplankton community composition were investigated using bioassays of natural phytoplankton communities to measure phytoplankton responses to different concentrations of TCS ranging from 1 to 200μgl^-1. The EC₅₀ (the concentration of an inhibitor where the growth is reduced by half) for phytoplankton groups (diatoms, chlorophytes, cryptophytes) examined in this ranged from 10.7 to 113.8μg TCS l^-1. Exposures resulted in major shifts in phytoplankton community composition at concentrations as low as 1.0μg TCS l^-1. This study demonstrates estuarine ecosystem sensitivity to TCS exposure and highlights potential alterations in phytoplankton community composition at what are typically environmental concentrations of TCS in urbanized estuaries.

Pulmonary apoptotic and oxidative damaging effects of Triclosan alone or in combination with Fluoride in Sprague Dawley rats

This study aimed to assess the potential apoptotic and oxidative damaging impacts of Triclosan (TCS) and Sodium Fluoride (NaF) administered separately or in combination, in rats for thirty days. For this purpose, forty immature female Sprague-Dawley rats were equally allocated into five groups. TCS group administered 185mg TCS/kg Bw dissolved in distilled water (DW), while its control group received only DW. NaF group was given 50mg/kg NaF in corn oil BW and its respective control had corn oil alone. The co-treated group was administered TCS and NaF. The oxidative stress biomarkers were evaluated in lung tissue homogenate and apoptotic proteins (BcL-2 and Caspase-3) expression were quantified in lung tissues. The results of TCS or NaF treated groups revealed a prominent depletion of super oxide dismutase (SOD), Catalase (CAT) and Glutathione (GSH) in lung tissue homogenate. On contrary, a marked increase in the tissue levels of Malondialdehyde (MDA) and lactate dehydrogenase (LDH) enzymatic assay levels. The co-exposed group evoked less severity in the oxidative stress biomarkers concentration than individually exposed groups. The apoptotic genes protein expression was significantly higher in TCS or NaF treated rats when compared to the control with intense to moderate immunolabeling of the bronchiolar lining epithelium and surrounding mononuclear inflammatory cells. On the contrary, no significant differences were detected in the expression of the investigated apoptotic biomarkers between the control and the combined exposed group. We concluded that the exposure to either TCS or NaF resulted in significant perturbations in lung tissue after short term oral administration at variable instances but the co-exposure resulted in less severe toxicological consequences.

Triclosan exposure, transformation, and human health effects

Triclosan (TCS) is an antimicrobial used so ubiquitously that 75% of the US population is likely exposed to this compound via consumer goods and personal care products. In September 2016, TCS was banned from soap products following the risk assessment by the US Food and Drug Administration (FDA). However, TCS still remains, at high concentrations, in other personal care products such as toothpaste, mouthwash, hand sanitizer, and surgical soaps. TCS is readily absorbed into human skin and oral mucosa and found in various human tissues and fluids. The aim of this review was to describe TCS exposure routes and levels as well as metabolism and transformation processes. The burgeoning literature on human health effects associated with TCS exposure, such as reproductive problems, was also summarized.

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.

Chronic effects of triclosan on embryonic development of Chinese toad, Bufo gargarizans

Triclosan (TCS) is commonly used worldwide in a range of personal care and sanitizing products. The aim of this study was to evaluate potential effects of TCS exposure on embryonic development of Bufo gargarizans, an endemic frog species in China. Standard Gosner stage 3 B. gargarizans embryos were exposed to 10 ~ 150 μg/L TCS during embryogenesis. Survival, total length, weight, developmental stage, duration of different embryo stages, malformation, and type II and III deiodinase (D2 and D3) expression were measured. Inhibitory effects on embryo developmental stage, total length and weight were found at 30 ~ 150 μg/L TCS. Moreover, the duration of embryonic development was increased at gastrula, neural, circulation, and operculum development stage in TCS-treated groups. In addition, TCS exposure induced morphological malformations in B. gargarizans embryos, which are characterized by hyperplasia, abdominal edema, and axial flexures. Furthermore, our results showed that the expression of D2 in embryos was probably down-regulated at 60 and 150 μg/L TCS, but its spatial expression patterns was not affected by TCS. In summary, our study suggested that TCS exposure not only resulted in delayed growth and development but also caused teratogenic effects in B. gargarizans embryos, and the developmental effects of TCS at high concentrations may be associated with disruption of THs homeostasis. Although further studies are necessary, the present findings could provide a basis for understanding on harmful effects and the potential mechanisms of TCS in amphibian embryos.

Antimicrobial agent triclosan is a proton ionophore uncoupler of mitochondria in living rat and human mast cells and in primary human keratinocytes

Triclosan (TCS) is an antimicrobial used widely in hospitals and personal care products, at ~10 mm. Human skin efficiently absorbs TCS. Mast cells are ubiquitous key players both in physiological processes and in disease, including asthma, cancer and autism. We previously showed that non-cytotoxic levels of TCS inhibit degranulation, the release of histamine and other mediators, from rat basophilic leukemia mast cells (RBL-2H3), and in this study, we replicate this finding in human mast cells (HMC-1.2). Our investigation into the molecular mechanisms underlying this effect led to the discovery that TCS disrupts adenosine triphosphate (ATP) production in RBL-2H3 cells in glucose-free, galactose-containing media (95% confidence interval EC50 = 7.5-9.7 µm), without causing cytotoxicity. Using these same glucose-free conditions, 15 µm TCS dampens RBL-2H3 degranulation by 40%. The same ATP disruption was found with human HMC-1.2 cells (EC50 4.2-13.7 µm), NIH-3 T3 mouse fibroblasts (EC50 4.8-7.4 µm) and primary human keratinocytes (EC50 3.0-4.1 µm) all with no cytotoxicity. TCS increases oxygen consumption rate in RBL-2H3 cells. Known mitochondrial uncouplers (e.g., carbonyl cyanide 3-chlorophenylhydrazone) previously were found to inhibit mast cell function. TCS-methyl, which has a methyl group in place of the TCS ionizable proton, affects neither degranulation nor ATP production at non-cytotoxic doses. Thus, the effects of TCS on mast cell function are due to its proton ionophore structure. In addition, 5 µm TCS inhibits thapsigargin-stimulated degranulation of RBL-2H3 cells: further evidence that TCS disrupts mast cell signaling. Our data indicate that TCS is a mitochondrial uncoupler, and TCS may affect numerous cell types and functions via this mechanism. Copyright © 2015 John Wiley & Sons, Ltd.

Triclosan is a mitochondrial uncoupler in live zebrafish

Triclosan (TCS) is a synthetic antimicrobial agent used in many consumer goods at millimolar concentrations. As a result of exposure, TCS has been detected widely in humans. We have recently discovered that TCS is a proton ionophore mitochondrial uncoupler in multiple types of living cells. Here, we present novel data indicating that TCS is also a mitochondrial uncoupler in a living organism: 24-hour post-fertilization (hpf) zebrafish embryos. These experiments were conducted using a Seahorse Bioscience XF^e 96 Extracellular Flux Analyzer modified for bidirectional temperature control, using the XF96 spheroid plate to position and measure one zebrafish embryo per well. Using this method, after acute exposure to TCS, the basal oxygen consumption rate (OCR) increases, without a decrease in survival or heartbeat rate. TCS also decreases ATP-linked respiration and spare respiratory capacity and increases proton leak: all indicators of mitochondrial uncoupling. Our data indicate, that TCS is a mitochondrial uncoupler in vivo, which should be taken into consideration when assessing the toxicity and/or pharmaceutical uses of TCS. This is the first example of usage of a Seahorse Extracellular Flux Analyzer to measure bioenergetic flux of a single zebrafish embryo per well in a 96-well assay format. The method developed in this study provides a high-throughput tool to identify previously unknown mitochondrial uncouplers in a living organism. Copyright © 2016 John Wiley & Sons, Ltd.

Accumulation of triclosan from diet and its neuroendocrine effects in Atlantic croaker (Micropogonias undulatus) under two temperature Regimes

Rising water temperatures due to climate change may increase the uptake and effects of triclosan in aquatic organisms. Our objectives were to investigate the accumulation of dietary triclosan and its neuroendocrine effects in Atlantic croaker, an estuarine fish, under two temperatures and during depuration. A pilot study was used to select a dietary exposure of 50 mg/kg. For 10 days, fish were exposed to one of four diet/temperature treatments (n = 16/treatment): normal diet at 26 °C and 29 °C and triclosan-treated diet at 26 °C and 29 °C. Fish exposed to triclosan at 26 °C accumulated 2.6 mg/kg wet weight on average versus 5.6 mg/kg wet weight at 29 °C. Triclosan exposure significantly impacted reflexes, resulting in the loss of the dorsal fin reflex (DS) in 53% of fish, while temperature and triclosan-temperature interactions were not significant. Triclosan body burden did not significantly predict DS loss. There were no significant differences in thyroid hormone levels among groups. Triclosan-treated fish at 26 °C were fed untreated pellets for 5 additional weeks. Two fish lost the DS during the first depuration week, and no affected fish recovered the reflex. These results have important implications for fish and their predators, as the DS may be important for swimming performance and social patterning.

The Effect of Perfluorooctane Sulfonate, Exposure Time, and Chemical Mixtures on Methanogenic Community Structure and Function

A plethora of organic micropollutant mixtures are found in untreated municipal wastewater. Anaerobic digesters receive large loadings of hydrophobic micropollutants that sorb to wastewater biosolids. Despite micropollutants being pervasive as mixtures, little research is available to explain the impact that mixtures of compounds, as well as exposure time, have on microbial communities in anaerobic digesters. Perfluorooctane sulfonate (PFOS) was added to anaerobic enrichment cultures in both short-term (14 days) and long-term (140 days) studies to determine the impact of exposure time. Additionally, triclosan was added during the experiments to investigate the impact of mixtures on community structure and function. PFOS did not alter methane production in short-term studies, but in long-term studies, methane production increased, consistent with our hypothesis that PFOS may act as a metabolic uncoupler. The impact of triclosan on methane production was exacerbated when PFOS was already present in the anaerobic enrichment cultures. Triclosan also had greater impacts on microbial community structures in the bottles that had been exposed to PFOS long-term. These results demonstrate that both chemical mixtures and exposure time are important parameters to address when trying to define the impacts of micropollutants on anaerobic microbial communities.

Mitochondrial toxicity of triclosan on mammalian cells

Effects of triclosan (5-chloro-2'-(2,4-dichlorophenoxy)phenol) on mammalian cells were investigated using human peripheral blood mono nuclear cells (PBMC), keratinocytes (HaCaT), porcine spermatozoa and kidney tubular epithelial cells (PK-15), murine pancreatic islets (MIN-6) and neuroblastoma cells (MNA) as targets. We show that triclosan (1-10 μg ml-1) depolarised the mitochondria, upshifted the rate of glucose consumption in PMBC, HaCaT, PK-15 and MNA, and subsequently induced metabolic acidosis. Triclosan induced a regression of insulin producing pancreatic islets into tiny pycnotic cells and necrotic death. Short exposure to low concentrations of triclosan (30 min, ≤1 μg/ml) paralyzed the high amplitude tail beating and progressive motility of spermatozoa, within 30 min exposure, depolarized the spermatozoan mitochondria and hyperpolarised the acrosome region of the sperm head and the flagellar fibrous sheath (distal part of the flagellum). Experiments with isolated rat liver mitochondria showed that triclosan impaired oxidative phosphorylation, downshifted ATP synthesis, uncoupled respiration and provoked excessive oxygen uptake. These exposure concentrations are 100-1000 fold lower that those permitted in consumer goods. The mitochondriotoxic mechanism of triclosan differs from that of valinomycin, cereulide and the enniatins by not involving potassium ionophoric activity.

Triclosan causes toxic effects to algae in marine biofilms, but does not inhibit the metabolic activity of marine biofilm bacteria

Effects of the antimicrobial agent triclosan to natural periphyton communities (biofilms, comprising primarily microalgae and bacteria) were assessed in two independent experiments during spring and summer. For that purpose a semi-static test system was used in which periphyton was exposed to a concentration range of 5-9054 nmol/L triclosan. Effects on algae were analyzed as content and composition of photosynthetic pigments. The corresponding EC50 values were 39.25 and 302.45 nmol/L for the spring and summer experiment, respectively. Effects on periphytic bacteria were assessed as effects on carbon utilization patterns, using Biolog Ecoplates. No inhibition of either total carbon utilization or functional diversity was observed, indicating a pronounced triclosan tolerance of the marine bacteria. In contrast, a small stimulation of the total carbon utilization was observed at triclosan concentrations exceeding 100 nmol/L.

Toxic effects of triclosan on the detoxification system and breeding of Daphnia magna

The toxic effects of different concentrations of Triclosan (TCS) (1-128 μg/L) on Daphnia magna (D. magna) were investigated by acute (48 h) and chronic (21-day) toxicity tests. The response of antioxidase system and Phase I metabolism process of D. magna exposed to TCS were investigated by measuring a series of biomarkers including glutathione S-transferase (GST), catalase (CAT), superoxide dismutase (SOD), malondialdehyde (MDA), 7-ethoxyresorufin O-deethylase (EROD), Erythromycin N-demethylase (ERND) and Aminopyrine N-demethylase (APND). The 48 h LC50 of TCS was 330 μg/L for D. magna. In the chronic test, total number of neonates per female, body length and the intrinsic rate of natural increase (r) of D. magna increased at the low exposure concentrations (1-16 μg/L) and decreased at the high concentrations (64-128 μg/L), while the total number of molting per adult decreased continually. The GST and CAT activities showed no significant increase in all treatments, and SOD activities were induced after 24-h exposure and inhibited after 48-h exposure at 4-128 μg/L of concentrations. The MDA content increased after 6-h exposure but decreased after 48-h exposure at 4-128 μg/L. EROD activities initially increased after 6-h exposure, but decreased after 24 and 48-h exposure, ERND and APND activities showed a similar temporal pattern among different treatments groups. SOD, MDA and APND were sensitive to TCS, thus they are suitable as potential biomarkers for the exposure to TCS.

Development of aquatic life criteria for triclosan and comparison of the sensitivity between native and non-native species

Triclosan (TCS) is an antimicrobial agent which is used as a broad-spectrum bacteriostatic and found in personal care products, and due to this it is widely spread in the aquatic environment. However, there is no paper dealing with the aquatic life criteria of TCS, mainly result from the shortage of toxicity data of different taxonomic levels. In the present study, toxicity data were obtained from 9 acute toxicity tests and 3 chronic toxicity tests using 9 Chinese native aquatic species from different taxonomic levels, and the aquatic life criteria was derived using 3 methods. Furthermore, differences of species sensitivity distributions (SSD) between native and non-native species were compared. Among the tested species, demersal fish Misgurnus anguillicaudatus was the most sensitive species, and the fishes were more sensitive than the aquatic invertebrates of Annelid and insect, and the insect was the least sensitive species. The comparison showed that there was no significant difference between SSDs constructed from native and non-native taxa. Finally, a criterion maximum concentration of 0.009 mg/L and a criterion continuous concentration of 0.002 mg/L were developed based on different taxa, according to the U.S. Environmental Protection Agency guidelines.

Allergic diseases and air pollution

The prevalence of allergic diseases has been increasing rapidly, especially in developing countries. Various adverse health outcomes such as allergic disease can be attributed to rapidly increasing air pollution levels. Rapid urbanization and increased energy consumption worldwide have exposed the human body to not only increased quantities of ambient air pollution, but also a greater variety of pollutants. Many studies clearly demonstrate that air pollutants potently trigger asthma exacerbation. Evidence that transportation-related pollutants contribute to the development of allergies is also emerging. Moreover, exposure to particulate matter, ozone, and nitrogen dioxide contributes to the increased susceptibility to respiratory infections. This article focuses on the current understanding of the detrimental effects of air pollutants on allergic disease including exacerbation to the development of asthma, allergic rhinitis, and eczema as well as epigenetic regulation.

Triclosan inhibits arbuscular mycorrhizal colonization in three wetland plants

In terrestrial ecosystems, plant growth, plant community structure, and ultimately the ecosystem services provided by plants are dependent on the presence and composition of below ground arbuscular mycorrhizal (AM) fungal communities. AM fungi form obligate symbioses with plants providing nutrients to their host plants in exchange for photosynthates. While AM have been found in most wetland ecosystems, the effects of urban contaminants on AM associations are largely unknown. Triclosan (5-chloro-2-[2,4-dichlorophenoxy]phenol; TCS) is a widespread contaminant found in surface waters throughout North America and in addition to antimicrobial properties is purported to have antifungal properties. To determine the effects of TCS on arbuscular mycorrhizal associations, we exposed AM inoculated wetland plant species (Eclipta prostrata, Hibiscus laevis, and Sesbania herbacea) to TCS at concentrations of 0.0, 0.4 and 4.0 μg/L in a continuous flow-through exposure system. TCS exposure caused significant reductions in hyphal and arbuscular colonization while no significant effect was detected for vesicular colonization. Across all species, hyphal colonization was significantly higher in controls (18.58 ± 1.84%) compared to 0.4 and 4.0 μg/L (10.20 ± 1.34% and 9.86 ± 1.32% respectively) TCS treatments. Similarly, arbuscular colonization was significantly higher in the controls (4.58 ± 0.75%) compared to 0.4 μg/L (2.20 ± 0.38%) and 4.0 μg/L (1.22 ± 0.24%) TCS exposures. Since our lowest effect concentration, 0.4 μg/L, lies within the range of concentrations found in North American streams it is plausible that AM colonization has been impacted in streams receiving WWTP effluent. Further studies are required to understand the mechanism of TCS inhibition of mycorrhizal colonization in wetland plant species as well as the potential ecological consequences that a decline in the AM colonization levels may represent.

Biological effects of environmentally relevant concentrations of the pharmaceutical Triclosan in the marine mussel Perna perna (Linnaeus, 1758)

Triclosan (5-Chloro-2-(2,4-dichlorophenoxy) phenol) is an antibacterial compound widely employed in pharmaceuticals and personal care products. Although this emerging compound has been detected in aquatic environments, scarce information is found on the effects of Triclosan to marine organisms. The aim of this study was to evaluate the toxicity of a concentration range of Triclosan through fertilization assay (reproductive success), embryo-larval development assay (early life stage) and physiological stress (Neutral Red Retention Time assay - NRRT) (adult stage) in the marine sentinel organism Perna perna. The mean inhibition concentrations for fertilization (IC(50) = 0.490 mg L(-1)) and embryo-larval development (IC(50) = 0.135 mg L(-1)) tests were above environmental relevant concentrations (ng L(-1)) given by previous studies. Differently, significant reduction on NRRT results was found at 12 ng L(-1), demonstrating the current risk of the continuous introduction of Triclosan into aquatic environments, and the need of ecotoxicological studies oriented by the mechanism of action of the compound.

Effects of triclosan in the freshwater mussel Dreissena polymorpha: a proteomic investigation

Triclosan (TCS, 5-chloro-2-(2,4-dichlorophenoxy)phenol) is commonly used in several personal care products, textiles, and children's toys. Because the removal of TCS by wastewater treatment plants is incomplete, its environmental fate is to be discharged into freshwater ecosystems, where its ecotoxicological impact is still largely unexplored. Previously, we began a structured multi-tiered approach in order to evaluate TCS toxicity in the freshwater mussel Dreissena polymorpha. The results of our previous studies, based on in vitro and in vivo experiments, highlighted a pronounced cytogenotoxic effect exerted by TCS, and showed that an increase in oxidative stress was likely to be one of its main toxic mechanisms. In this work, in order to investigate TCS toxicity mechanisms in aquatic non-target species in greater depth, we decided to use a proteomic approach, analysing changes in protein expression profiles in gills of D. polymorpha exposed for seven days to TCS. Moreover, thiobarbituric acid reactive substances (TBARS) were measured to investigate further the role played by TCS in inducing oxidative stress. Finally, TCS bioaccumulation in mussel tissues was also assessed, to ensure an effective accumulation of the toxicant. Our results not only confirmed the role played by TCS in inducing oxidative stress, but furthered knowledge about the mechanism exerted by TCS in inducing toxicity in an aquatic non-target organisms. TCS induced significant alterations in protein expression profiles in gills of D. polymorpha. The wide range of proteins affected suggested that this chemical has marked effects on various biological processes, especially those involved in calcium binding or stress response. We also confirmed that the proteomic analysis, using 2-DE and de novo sequencing, is a reliable and powerful approach to investigate cellular responses to pollutants in a non-model organism with few genomic sequences available in databases.

Anti-bacterial treatment of polyethylene by cold plasma for medical purposes

Polyethylene (PE) is one of the most widely used polymers in many industrial applications. Biomedical uses seem to be attractive, with increasing interest. However, PE it prone to infections and its additional surface treatment is indispensable. An increase in resistance to infections can be achieved by treating PE surfaces with substances containing antibacterial groups such as triclosan (5-Chloro-2-(2,4-dichlorophenoxy)phenol) and chlorhexidine (1,1'-Hexamethylenebis[5-(4-chlorophenyl)biguanide]). This work has examined the impact of selected antibacterial substances immobilized on low-density polyethylene (LDPE) via polyacrylic acid (PAA) grafted on LDPE by low-temperature barrier discharge plasma. This LDPE surface treatment led to inhibition of Escherichia coli and Staphylococcus aureus adhesion; the first causes intestinal disease, peritonitis, mastitis, pneumonia, septicemia, the latter is the reason for wound and urinary tract infections.

Triclosan: environmental exposure, toxicity and mechanisms of action

Triclosan [5-chloro-2-(2,4-dichlorophenoxy)phenol; TCS] is a broad spectrum antibacterial agent used in personal care, veterinary, industrial and household products. TCS is commonly detected in aquatic ecosystems, as it is only partially removed during the wastewater treatment process. Sorption, biodegradation and photolytic degradation mitigate the availability of TCS to aquatic biota; however the by-products such as methyltriclosan and other chlorinated phenols may be more resistant to degradation and have higher toxicity than the parent compound. The continuous exposure of aquatic organisms to TCS, coupled with its bioaccumulation potential, have led to detectable levels of the antimicrobial in a number of aquatic species. TCS has been also detected in breast milk, urine and plasma, with levels of TCS in the blood correlating with consumer use patterns of the antimicrobial. Mammalian systemic toxicity studies indicate that TCS is neither acutely toxic, mutagenic, carcinogenic, nor a developmental toxicant. Recently, however, concern has been raised over TCS's potential for endocrine disruption, as the antimicrobial has been shown to disrupt thyroid hormone homeostasis and possibly the reproductive axis. Moreover, there is strong evidence that aquatic species such as algae, invertebrates and certain types of fish are much more sensitive to TCS than mammals. TCS is highly toxic to algae and exerts reproductive and developmental effects in some fish. The potential for endocrine disruption and antibiotic cross-resistance highlights the importance of the judicious use of TCS, whereby the use of TCS should be limited to applications where it has been shown to be effective.

A review of personal care products in the aquatic environment: environmental concentrations and toxicity

Considerable research has been conducted examining occurrence and effects of human use pharmaceuticals in the aquatic environment; however, relatively little research has been conducted examining personal care products although they are found more often and in higher concentrations than pharmaceuticals. Personal care products are continually released into the aquatic environment and are biologically active and persistent. This article examines the acute and chronic toxicity data available for personal care products and highlights areas of concern. Toxicity and environmental data were synergized to develop a preliminary hazard assessment in which only triclosan and triclocarban presented any hazard. However, numerous PCPs including triclosan, paraben preservatives, and UV filters have evidence suggesting endocrine effects in aquatic organisms and thus need to be investigated and incorporated in definitive risk assessments. Additional data pertaining to environmental concentrations of UV filters and parabens, in vivo toxicity data for parabens, and potential for bioaccumulation of PCPs needs to obtained to develop definitive aquatic risk assessments.

Physiological effects and bioconcentration of triclosan on amphibian larvae

We examined the acute effects of triclosan (TCS) exposure, a common antimicrobial found as a contaminant in the field, on survival and physiology of amphibian larvae. LC50 values were determined after 96h for North American larval species: Acris crepitans blanchardii, Bufo woodhousii woodhousii, Rana sphenocephala, and for a developmental model: Xenopus laevis. Amphibian larvae were most sensitive to TCS exposure during early development based upon 96-h LC50 values. Heart rates for X. laevis and North American larvae exposed to TCS were variable throughout development. Metabolic rates of X. laevis and R. sphenocephala larvae exposed to TCS were significantly affected in larvae exposed to [50% LC50] and [LC50]. Tissue uptake and tissue bioconcentration factor (BCF) of TCS were investigated in X. laevis, B. woodhousii woodhousii, and R. sphenocephala. In general, a significant increase was observed as exposure concentration increased. Tissue BCF values were dependent upon stage and species. While TCS concentrations used here are higher than environmental concentrations, exposure to TCS was dependent upon species and developmental stage, with early developmental stages being most sensitive to TCS exposure.