Long-term Toxicity Tests Research Articles

Comparative Analysis of the Effect of Dietary Supplementation with Fermented and Water-Extracted Leaf Extracts of Eucommia ulmoides on Egg Production and Egg Nutrition.

Although the water extract of Eucommia ulmoides leaf (WEE) promotes egg laying in hens, its palatability is poor. To improve the palatability of E. ulmoides leaf, probiotic fermentation was used, and fermented extract E. ulmoides leaf (FEE) was prepared using Lactiplantibacillus plantarum. The safety of FEE was investigated using a long-term toxicity test, and no oxidative damage, inflammatory reactions, or histological lesions were observed in the experimental rats receiving dietary supplementation of FEE at 200 mg/kg, suggesting that FEE is suitable for long-term feeding. Subsequently, dietary supplementation of FEE (group C) in comparison with dietary supplementation of WEE (group B), as well as a control (group A), was applied in the hen industry. Laying performance, egg quality, egg nutrition, egg flavor, and the gut microbiome were analyzed comparatively. Interestingly, the laying rate was observed to be four percentage points higher with dietary supplementation of FEE at 200 mg/kg compared with the control and two percentage points higher compared with the dietary addition of WEE at the same dosage. Simultaneously, a slight upregulation in daily feed consumption was determined in the FEE-supplemented group compared with the blank control and the WEE-supplemented group, indicating that the inclusion of FEE stimulated the hens' appetite. Moreover, variations in egg amino acids, fatty acids, and volatile components were obtained with either dietary addition, FEE or WEE, implying that dietary supplementation of the fermented and water-extracted E. ulmoides leaf extracts contributed to egg flavor change. Furthermore, variations in the gut microbiota were mediated by FEE, increasing the relative abundance of the genus Lactobacillus. These alterations in gut microbiota were tightly related to improved laying performance and egg flavor changes. Our results indicate that FEE is a better alternative feed additive in the hen industry than WEE.

Layer-by-layer self-assembly method improves the performance and cytocompatibility of 3D printing ODMA-GelMA hydrogel

The GelMA hydrogels are biomaterials with excellent biocompatibility and cellular activity. However, their application is limited due to their poor mechanical properties. To enhance the mechanical properties of GelMA, we incorporated ODMA into GelMA for the sequential assembly of RSF (raw silk fiber protein) and CHI (chitosan) through electrostatic interactions, constructing a multi-layer composite membrane on the hydrogel surface. We conducted microscopic morphology analysis, evaluated mechanical properties, assessed cytocompatibility, and performed short-term and long-term material toxicity testing. Our results showed that mechanical properties were significantly enhanced when the 10-layer (RSF/CHI) composite film was assembled on the surface of ODMA-GelMA hydrogel. And they also exhibited excellent cytocompatibility. The improved GelMA hydrogel has the potential for biomedical applications in 3D printing as a substitute for artificial organs.

Chronic toxicity of pharmaceuticals to the benthic green alga Closterium ehrenbergii

Pharmaceuticals in the environment have emerged to a topic of global concern. Since these substances are designed to be biologically active, hazardous effects on non-target organisms are frequently reported. Here, the effects of five pharmaceuticals, one radiocontrast agent, and one degradation product on the freshwater green alga Closterium ehrenbergii were evaluated after chronic exposure of 168 h. Growth and maximum quantum yield (FV/FM) were used as endpoints and complemented by the assessment of morphology and chlorophyll fluorescence. We found that the tested antibiotics Ciprofloxacin and Ofloxacin impaired chloroplast integrity, resulting in a reduction of FV/FM from 0.1 mg/L. The disintegration of chloroplasts at higher concentrations (c = 0.3 and 0.8 mg/L, respectively) was visualized by brightfield and fluorescence microscopy. In contrast, Sulfamethoxazole interfered with cell division, leading to malformation of cells from 0.8 mg/L. Furthermore, the antibiotics exhibited a latency period of 72 h after which they started to reveal their true effects. Therefore, the importance of long-term toxicity testing is outlined in order to avoid underestimation of toxic effects of pharmaceuticals. Based on the EC10 values obtained, the antibiotics were considered to meet the criteria for classification as toxic to aquatic life with long lasting effects. The other test substances were found to exert no effects on C. ehrenbergii or only at very high concentrations and were classified as nontoxic.

Adequate nutrient intake mitigate the toxic effects of bromate on the rotifer Brachionus calyciflorus.

Bromate is receiving increased attention as a typical disinfection by-product in aquatic environments, but bromate toxicity tests on invertebrate such as Brachionus calyciflorus rotifer are inadequate. In the present study, the long-term toxicity tests on B. calyciflorus were performed during 21 days under the exposure of different bromate concentrations and two algal density conditions. Furthermore, we evaluated the feeding behaviors of the rotifers under the impact of bromate. The maximum population density of rotifers was significantly reduced at 100 and 200 mg/L bromate exposure at the two algal density conditions. However, we observed that the maximum population density and population growth rate of rotifers were higher at 3.0 × 106 cells/mL algal density than those at 1.0 × 106 cells/mL under the same conditions of bromate exposure. These results suggest that higher food density may have alleviated the negative effects of bromate on rotifers. Meanwhile, the ingestion rate at an algal density of 3.0 × 106 cells/mL was higher than that at 1.0 × 106 cells/mL. The present study provides a basic reference to comprehensively evaluate the toxic effects of bromate on aquatic organisms.

Effects of grafting on chemical constituents, toxicological properties, antithrombotic activity, and myocardial infarction protection of styrax secreted from the trunk of Liquidambar orientalis Mill.

Styrax, the balsam refined from the trunk of Liquidambar orientalis Mill. has a variety of applications in the perfumery and medical industry, especially for use in traditional Chinese medicine. However, the resources of styrax are in shortage due to being endangered of this plant. Grafting can improve the adaptability of plants to unfavorable environmental conditions. We tried to graft the L. orientalis Mill. on L. formosana Hance which was widely distributed in Jiangsu and Zhejiang provinces of China in an attempt to obtain styrax from grafted L. orientalis Mill. (grafted styrax, SG). Whether SG can become an alternative application of commercially available styrax (SC) need be further investigated. The components of SG were analyzed by GC-MS, and the results showed that the chromatograms of SG, SC, and styrax standard (SS) were consistent. The ration of 12 major chemical components based peak area in SG, SC, and SS were 93.95%, 94.24%, and 95.86% respectively. The assessment of toxicity, antithrombotic activity, and myocardial infarction protection of SG and SC was evaluated by using the zebrafish model, the results showed that SG and SC have the similar toxicological properties as evidenced by acute toxicity test, developmental toxicity and teratogenicity, and long-term toxicity test. Both SG and SC significantly decreased the thrombosis and increased blood flow velocity of zebrafish induced by adrenaline hydrochloride, inhibited myocardial apoptosis, myocardial infarction and myocardial inflammation in zebrafish induced by isoproterenol hydrochloride. Moreover, SG had an obvious improvement effect on cardiac output, while SC has no effect. Collectively, SG is similar to SC in chemical composition, toxicological properties, antithrombotic activity, and myocardial infarction protection effects, and may be used as a substitute for styrax to reduce the collection for wild L. orientalis Mill. and increase the available styrax resources.

Chronic toxicity testing including transcriptomics-based molecular profiling in Cloeon dipterum

The so-called EPT taxa have been shown to be highly sensitive to various environmental pollutants. However, there are only few published studies on toxicity testing with EPT representatives and there is a particular lack of protocols for chronic toxicity testing, e.g., for integration into species sensitivity distribution (SSD) approaches. To address this gap, we performed a long-term 38-day semi-static toxicity test with the European mayfly species Cloeon dipterum using the insecticide fipronil as model substance. The functionality of the test system was confirmed by the high emergence rate of 85% in the control condition. We found a high sensitivity with regard to larval development with an EC50 of 180 ng/L and a NOEC of 38.0 ng/L after 7 days exposure. After 38 days, an LC50 value of 185 ng/L and an EC50 value of 160 ng/L for emergence (both: NOEC = 38.0 ng/L) were calculated. In a short-term 7-day toxicity test, we found a similar effect on larval development. In addition to the physiological endpoints, we examined fipronil-induced gene expression changes at the transcriptome level in this test. Our results revealed a concentration-dependent increase in the number of differentially expressed genes, as well as observed effects on larval development. Notably, we identified marker gene candidates involved in nervous system development, mirroring the known mode-of-action of fipronil in C. dipterum. The affected genes primarily play crucial roles in neurological processes. Concluding, within this two-step approach we were able to identify fipronil effects on the sublethal physiological endpoint larval development and to complement these effects at the molecular level by gene expression changes in the transcriptome. Thus, this assay proved to be suitable to assess sublethal effects as well as the mode-of-action of substances in the non-standard organism C. dipterum already after a short-term exposure of 7 days. However, further testing is required to validate the procedure.

Exposure protocol for ecotoxicity testing of microplastics and nanoplastics.

Despite the increasing concern about the harmful effects of micro- and nanoplastics (MNPs), there are no harmonized guidelines or protocols yet available for MNP ecotoxicity testing. Current ecotoxicity studies often use commercial spherical particles as models for MNPs, but in nature, MNPs occur in variable shapes, sizes and chemical compositions. Moreover, protocols developed for chemicals that dissolve or form stable dispersions are currently used for assessing the ecotoxicity of MNPs. Plastic particles, however, do not dissolve and also show dynamic behavior in the exposure medium, depending on, for example, MNP physicochemical properties and the medium's conditions such as pH and ionic strength. Here we describe an exposure protocol that considers the particle-specific properties of MNPs and their dynamic behavior in exposure systems. Procedure 1 describes the top-down production of more realistic MNPs as representative of MNPs in nature and particle characterization (e.g., using thermal extraction desorption-gas chromatography/mass spectrometry). Then, we describe exposure system development for short- and long-term toxicity tests for soil (Procedure 2) and aquatic (Procedure 3) organisms. Procedures 2 and 3 explain how to modify existing ecotoxicity guidelines for chemicals to target testing MNPs in selected exposure systems. We show some examples that were used to develop the protocol to test, for example, MNP toxicity in marine rotifers, freshwater mussels, daphnids and earthworms. The present protocol takes between 24 h and 2 months, depending on the test of interest and can be applied by students, academics, environmental risk assessors and industries.

PEG2000-PLA-based nanoscale polymeric micelles reduce paclitaxel-related toxicity in beagle dogs

Nanoplatform-based drug delivery plays an important role in clinical practice. Polymeric micellar (Pm) nanocarriers have been demonstrated to reduce the toxicity of paclitaxel in rats and non-small cell lung cancer (NSCLC) patients. However, the underlying toxicological profile needs to be further illustrated. Here, we used beagles as study subjects and sought to further observe the toxicological profile of polymeric micellar paclitaxel (Pm-Pac) via acute toxicity tests and short-term and long-term toxicity tests. The results from the acute toxicity test indicated that the lethal dose of Pm-Pac in beagles was 20–30 mg/kg, and the acute toxicity-targeted organs were the digestive system and immuno-haematopoietic system. The short-term toxicity test suggested that paclitaxel-induced toxicity (peripheral neuropathy toxicity, haemopoietic toxicity, heart system toxicity, and so on) in beagles can be reduced when paclitaxel is delivered via the Pm delivery system. The long-term toxicity test suggested that Pm-Pac can reduce haemopoietic toxicity in beagles. Collectively, this study provides novel insight into the toxicological profile of Pm-Pac in healthy beagles and provides a potential basis for promising clinical combination strategies in the future.

Preclinical Short-term and Long-term Safety of Human Bone Marrow Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) have become a promising therapeutic method. More safety data are needed to support clinical studies in more diseases. The aim of this study was to investigate the short- and long-term safety of human bone marrow–derived MSCs (hBMMSCs) in mice. In the present study, we injected control (saline infusion only), low (1.0 × 106/kg), medium (1.0 × 107/kg), and high (1.0 × 108/kg) concentrations of hBMMSCs into BALB/c mice. The safety of the treatment was evaluated by observing changes in the general condition, hematology, biochemical indices, pathology of vital organs, lymphocyte subsets, and immune factor levels on days 14 and 150. In the short-term toxicity test, no significant abnormalities were observed in the hematological and biochemical parameters between the groups injected with hBMMSCs, and no significant damage was observed in the major organs, such as the liver and lung. In addition, no significant differences were observed in the toxicity-related parameters among the groups in the long-term toxicity test. Our study also demonstrates that mice infused with different doses of hBMMSCs do not show abnormal immune responses in either short-term or long-term experiments. We confirmed that hBMMSCs are safe through a 150-day study, demonstrating that this is a safe and promising therapy and offering preliminary safety evidence to promote future clinical applications of hBMMSCs in different diseases.

Efficiency of ant-control agents in colony-level oral toxicity tests using Tetramorium tsushimae (Hymenoptera: Formicidae) for post-establishment control of the red imported fire ant, Solenopsis invicta (Hymenoptera: Formicidae)

The red imported fire ant Solenopsis invicta Buren (Hymenoptera: Formicidae) causes serious damage worldwide as an invasive alien species. The species has expanded its range to the Pacific Rim since 2000s and Japan has faced its multiple introductions since 2017. While colony-level control methods are urgently needed, testing living colonies of the unestablished species is challenging especially due to various restrictions under the COVID-19 pandemic. Here, we proposed alternative long-term toxicity assays using artificial colonies of Tetramorium tsushimae Emery (Hymenoptera: Formicidae), a Japanese native species belonging to the same subfamily (Myrmicinae) as S. invicta. We conducted an acute toxicity test to determine if T. tsushimae is a suitable substitute for S. invicta using fipronil and found the LD50 value in T. tsushimae was close to that in S. invicta. Then, we conducted the long-term toxicity test with fipronil and two insect growth regulators (pyriproxyfen and etoxazole) using artificial colonies of T. tsushimae. All workers and larvae in the fipronil-treated colonies died within 3 days of treatment initiation. Emergence of new workers was observed after 18 days in the etoxazole-treated and control colonies, but not in the pyriproxyfen-treated colonies. We concluded that fipronil was the most promising insecticide for post-establishment control, and pyriproxyfen was effective as a toxic-bait agent for colony-level control.

A Rational Approach to Drug Repositioning in β-thalassemia: Induction of Fetal Hemoglobin by Established Drugs.

Drug repositioning and the relevance of orphan drug designation for β-thalassemia is reviewed. Drug repositioning and similar terms ('drug repurposing', 'drug reprofiling', 'drug redirecting', 'drug rescue', 'drug re-tasking' and/or 'drug rediscovery') have gained great attention, especially in the field or rare diseases (RDs), and represent relevant novel drug development strategies to be considered together with the "off-label" use of pharmaceutical products under clinical trial regimen. The most significant advantage of drug repositioning over traditional drug development is that the repositioned drug has already passed a significant number of short- and long-term toxicity tests, as well as it has already undergone pharmacokinetic and pharmacodynamic (PK/PD) studies. The established safety of repositioned drugs is known to significantly reduce the probability of project failure. Furthermore, development of repurposed drugs can shorten much of the time needed to bring a drug to market. Finally, patent filing of repurposed drugs is expected to catch the attention of pharmaceutical industries interested in the development of therapeutic protocols for RDs. Repurposed molecules that could be proposed as potential drugs for β-thalassemia, will be reported, with some of the most solid examples, including sirolimus (rapamycin) that recently has been tested in a pilot clinical trial.

A Rational Approach to Drug Repositioning in β-thalassemia: Induction of Fetal Hemoglobin by Established Drugs.

Drug repositioning and the relevance of orphan drug designation for β-thalassemia is reviewed. Drug repositioning and similar terms ('drug repurposing', 'drug reprofiling', 'drug redirecting', 'drug rescue', 'drug re-tasking' and/or 'drug rediscovery') have gained great attention, especially in the field or rare diseases (RDs), and represent relevant novel drug development strategies to be considered together with the "off-label" use of pharmaceutical products under clinical trial regimen. The most significant advantage of drug repositioning over traditional drug development is that the repositioned drug has already passed a significant number of short- and long-term toxicity tests, as well as it has already undergone pharmacokinetic and pharmacodynamic (PK/PD) studies. The established safety of repositioned drugs is known to significantly reduce the probability of project failure. Furthermore, development of repurposed drugs can shorten much of the time needed to bring a drug to market. Finally, patent filing of repurposed drugs is expected to catch the attention of pharmaceutical industries interested in the development of therapeutic protocols for RDs. Repurposed molecules that could be proposed as potential drugs for β-thalassemia, will be reported, with some of the most solid examples, including sirolimus (rapamycin) that recently has been tested in a pilot clinical trial.

Co-exposure of Monensin Increased the Risks of Atrazine to Earthworms.

Antibiotics could enter farmlands through sewage irrigation or manure application, causing combined pollution with pesticides. Antibiotics may affect the environmental fate of pesticides and even increase their bioavailability. In this study, the influence of monensin on the degradation, toxicity, and availability of atrazine in soil-earthworm microcosms was investigated. Monensin inhibited the degradation of atrazine, changed the metabolite patterns in soil, and increased the bioavailability of atrazine in earthworms. Atrazine and monensin had a significant synergistic effect on earthworms in the acute toxic test. In long-term toxicity tests, co-exposure of atrazine and monensin also led to worse effects on earthworms including oxidative stress, energy metabolism disruption, and cocoon production compared to single exposure. The expression of tight junction proteins was down-regulated significantly by monensin, indicating that the intestinal barrier of earthworms was weakened, possibly causing the increased bioavailability of atrazine. The expressions of heat shock protein 70 (Hsp70) and reproductive and ontogenetic factors (ANN, TCTP) were all downregulated in binary exposure, indicating that the resilience and cocoon production of earthworms were further weakened under combined pollution. Monensin disturbed the energy metabolism and weakened the intestinal barrier of earthworms. These results showed that monensin increased the risks of atrazine in agricultural areas.

A Rational Approach to Drug Repositioning in β-thalassemia: Induction of Fetal Hemoglobin by Established Drugs

Drug repositioning and the relevance of orphan drug designation for β-thalassemia is reviewed. Drug repositioning and similar terms ('drug repurposing', 'drug reprofiling', 'drug redirecting', 'drug rescue', 'drug re-tasking' and/or 'drug rediscovery') have gained great attention, especially in the field or rare diseases (RDs), and represent relevant novel drug development strategies to be considered together with the "off-label" use of pharmaceutical products under clinical trial regimen. The most significant advantage of drug repositioning over traditional drug development is that the repositioned drug has already passed a significant number of short- and long-term toxicity tests, as well as it has already undergone pharmacokinetic and pharmacodynamic (PK/PD) studies. The established safety of repositioned drugs is known to significantly reduce the probability of project failure. Furthermore, development of repurposed drugs can shorten much of the time needed to bring a drug to market. Finally, patent filing of repurposed drugs is expected to catch the attention of pharmaceutical industries interested in the development of therapeutic protocols for RDs. Repurposed molecules that could be proposed as potential drugs for β-thalassemia, will be reported, with some of the most solid examples, including sirolimus (rapamycin) that recently has been tested in a pilot clinical trial.

Clinical comprehensive evaluation of Huangkui Capsules in treatment of chronic kidney diseases

Based on Guidelines for the Management of Clinical Comprehensive Evaluation of Drugs(trial version 2021), this study aims to sort out the clinical evidence of Huangkui Capsules(HC) in the treatment of chronic kidney diseases in aspects of safety, effectiveness, economy, innovation, suitability, accessibility, and characteristics of traditional Chinese medicine( "6+1" dimensions) from real-world data, secondary literature evaluations, questionnaires, and public data, with the methods in evidence-based medicine, epidemiology, pharmacoeconomics, and health technology. Furthermore, with multi-criteria decision analysis(MCDA) model and CSC v2.0, the clinical value of the medicine is comprehensively assessed. All the above are to highlight the advantages and characteristics of HC and lay a basis for scientific decision-making by the medical management department. The dimensions are graded A, B, C, or D. According to the conclusions from phase Ⅳ clinical trial, spontaneous reporting system(SRS), systematic review and Meta-analysis, acute toxicity and long-term toxicity tests, it mainly results in the adverse reactions of nausea, abdominal distension, vomiting, pruritus, rash, and good prognosis in patients. According to the available research, the safety evidence is sufficient and the risk is controllable, so the safety of this medicine is grade B. According to Meta-analysis, HC in combination with conventional drugs in the treatment of chronic kidney disease is superior to conventional drugs alone in reducing urinary protein, serum creatinine concentration, and blood urea nitrogen. In addition, HC combined angiotensin receptor blocker(ARB) or angiotensin converting enzyme inhibitor(ACEI) is outstanding in improving total clinical effective rate, reducing 24 h urinary protein quantity, urinary albumin excretion rate, serum creatinine concentration, triglyceride, and total cholesterol in the treatment of diabetic nephropathy as compared with ARB or ACEI alone. As for chronic nephritis, the application together with ARB or ACEI can raise the total effective rate, reduce 24 h urinary protein content, serum creatinine concentration, and blood urea nitrogen, and delay the progress of the disease. HC boasts high-quality evidence in treating chronic kidney disease, diabetic nephropathy, and chronic nephritis. It has obvious clinical significance in treating chronic kidney disease and thus its efficacy in this aspect is grade B. It has outstanding clinical significance for diabetic nephropathy and chronic nephritis and corresponding and the effectiveness is grade A. As for the pharmacoeconomic value, HC combined with ARB or ACEI is more economical in the treatment of chronic kidney disease than Bailing Capsules combined with ARB or ACEI, with high-quality evidence, and thus the economy of the formula is grade B. HC is a key solution to the high urinary protein in patients with hypotension and chronic kidney disease. The innovation is evidenced by the methods to ensuring drug supply, community-level supply, drug safety, effectiveness, and reasonable price, as wells as the aspects of enterprise philosophy, equipment management, research and development in process and technology, enterprise management and marketing. Thus, the prescription is grade A in innovation. The suitability, as evidenced in drug administration, technical management, drug storage, information service, and medication, is grade B. The course of the medicine is affordable, and it is accessible in a wide range of areas and hospitals. Thus, the accessibility is grade A. HC was developed from an in-hospital preparation, with application in numerous patients and thus large-scale real-world data. As a result, HC is grade B in terms of characteristics of traditional Chinese medicine. After comprehensive evaluation, the clinical value of HC in treating chronic kidney disease is class B, and that for diabetic nephropathy and chronic nephritis is class A. The result is of great reference value for the basic clinical medication management.

HUC-MSCs: evaluation of acute and long-term routine toxicity testing in mice and rats.

Human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) are present in human umbilical connective tissue and can differentiate into various cell types. Our previous studies have proved that hUC-MSCs do not lead to allergies and tumorigenesis. In the present study, the acute and long-term toxicity of hUC-MSCs inmice and rats was evaluated. The acute toxicity of hUC-MSCs was assessed in 8-week-old mice receiving two caudal intravenous (i.v.) injections of hUC-MSCs at the maximum tolerated dose of 1.5 × 107 cells/kg with an interval of 8h and the observation period sustained for 14days. For the long-term toxicity evaluation, rats were randomly divided into control, low-dose (3.0 × 105 cells/kg), mid-dose (1.5 × 106 cells/kg), and high-dose (7.5 × 106 cells/kg) groups, which were treated with hUC-MSCs via a caudal i.v. injection every 3days for 90days. Weight and food intake evaluation was performed for all rats for 2weeks after the hUC-MSC administration. The animals were then sacrificed for hematological, blood biochemical, and pathological analyses, as well as organ index determination. We observed no obvious acute toxicity of hUC-MSCs in mice at the maximum tolerated dose. Long-term toxicity tests in rats showed no significant differences between HUC-MSC-treated and control groups in the following parameters: body weight, hematological and blood biochemical parameters, and histopathologic changes in the heart, liver, kidneys, and lungs. This study provides evidence of the safety of i.v. hUC-MSCs infusion for future clinical therapies.

Ecotoxicity and biodegradation of the bacteriostatic 3,3′,4′,5-tetrachlorosalicylanilide (TSCA) compared to the structurally similar bactericide triclosan

This article studies the ecotoxicity of 3,3′,4′,5-tetrachlorosalicylanilide (TCSA) using different bioassays and examines its fate in activated sludge batch experiments. Despite of the common use of TCSA as chemical uncoupler in wastewater treatment systems and as preservative in several products, limited data has been published for its ecotoxicity, while no information is available for its biodegradation. Among different bioassays, the highest toxicity of TSCA was noticed for Daphna magna (48-h LC50: 0.054 mg L−1), followed by Vibrio fischeri (15-min EC50: 0.392 mg L−1), Lemna minor, (7-d EC50: 5.74 mg L−1) and activated sludge respiration rate (3-h EC50: 31.1 mg L−1). The half-life of TSCA was equal to 7.3 h in biodegradation experiments with activated sludge, while use of mass balances showed that 90% of this compound is expected to be removed in an aerobic activated sludge system, mainly due to biodegradation. A preliminary risk assessment of TSCA using the Risk Quotient methodology showed possible ecological threat in rivers where wastewater is diluted up to 100-fold. Comparison with the structurally similar 5-chloro-2-(2,4-dichlorophenoxy)phenol (triclosan, TCS) showed that both compounds have similar biodegradation potential and seem to cause analogous toxicity to Vibrio fischeri and activated sludge. Specifically, TCS was biodegraded quite rapidly by activated sludge (half-life: 6.2 h), while EC50 values equal to 0.134 mg L−1 and 39.9 mg L−1 were calculated for Vibrio fischeri, and activated sludge respiration rate. Future research should focus on monitoring of TSCA concentrations in the environment and study its effects in long-term toxicity and bioaccumulation tests.

Rethinking toxicity testing: Influence of aging on the outcome of long-term toxicity testing and possible remediation

Traditionally, toxicity testing is conducted at fixed dose rates (i.e., mg/kg/day) without considering life-changing events, e.g., stress, sickness, aging- and/or pregnancy-related changes in physical, physiological and biochemical parameters. In humans, life-changing events may cause systemic dose non-proportionality requiring modulation of drug dosage; similar changes occur in animals altering systemic dose during chronic/carcinogenic testing leading to “late-occurring” effects in some studies. For example, propylene monomethyl ether, an industrial chemical, initially induced sedation in rats and mice with recovery upon induction of hepatic CYPs after ~1 week. Sedation reappeared in rats but not in mice after ~12 months of exposure due to decreased CYP activity in rats, elderly mice were able to maintain slightly higher CYP activity avoiding recurrence of sedation. The systemic dose of two pharmaceuticals (doxazosin and brimonidine tartrate) increased up to 6-fold in ≥12-month old rats with no toxicity. In a rat reproductive toxicity study, systemic dose of 2,4-D, an herbicide, rapidly increased due to increased consumption of 2,4-D-fortified diet during pregnancy, lactation and neonatal growth, requiring adjustment to maintain the targeted systemic dose. Ideally, toxicological studies should be based on systemic dose with the option of modulating external dose rates to maintain the targeted systemic dose. Systemic dose can easily be monitored in selected core study animals at desired intervals considering recent developments in sampling and analysis at a fraction of the overall cost of a study.

Influence of remediation on sediment toxicity within the Grand Calumet River, Indiana, USA

The Grand Calumet River (GCR), located in northern Indiana, is contaminated due to a wide range of historical industrial activities. This study was conducted to determine the influence of sediment remediation within the GCR on concentrations of chemical contaminants and toxicity to sediment-dwelling organisms. Between 2005 and 2016, sediments with high concentrations of metals and toxic organic compounds were remediated through a combination of removal, addition of activated carbon and organoclay amendments, and capping with sand or relatively uncontaminated sediment. Short-term and long-term sediment toxicity tests with the amphipod Hyalella azteca, the midge Chironomus dilutus, and the mussel Lampsilis siliquoidea were conducted with samples collected in 2013, 2015, and 2017, from 29 sites, including both remediated and non-remediated sites. Sediment chemistry and toxicity data for three groups of remediated sites (US Steel, West Branch, and East Branch) were compared to samples from contaminated but unremediated sites and to relatively uncontaminated reference sites. In general, remediated sediments had lower levels of PAHs, PCBs and metals, although sediments from the US Steel area still had elevated levels of PAH, PCB and chromium. Sediments from the three remediated sites and from reference sites showed significantly reduced toxic effects in short-term sediment bioassays, compared to unremediated sites. Variation in the long-term success of remediation may reflect site-specific factors such as the type of remediation and the potential for recontamination from uncontrolled sources.

A novel evaluation method for determining drug-induced hepatotoxicity using 3D bio-printed human liver tissue

Predicting drug-induced liver injury is important in early stage drug discovery; however, an accurate prediction with existing hepatotoxicity evaluation tools is difficult. Conventional monolayer (2D) cultures have short viabilities and are therefore inappropriate for performing long-term toxicity tests. Conventionally used 200-μm spheroids also have toxicity detection limits. The goal of this study was to develop a humanized liver tissue capable of evaluating long-term toxicity with high sensitivity. Spheroids consisting of co-cultured cryopreserved primary human hepatocytes and human hepatic stellate cells were developed using a 3D bio-printer. The “3D bio-printed liver tissue”, of ∼1 mm, was then used for long-term viability assessments (over 25 days) based on ATP, albumin, and urea levels. Hepatotoxicity evaluation was performed by analyzing the expression of genes involved in drug metabolism and transport over a 2-week drug exposure period. The 3D bio-printed liver tissue showed improved viability and enhanced gene expression of enzymes related to drug metabolism and transport, as compared to the controls. Additionally, the 3D bio-printed liver tissue demonstrated a high sensitivity for hepatotoxicity evaluation when combined with pathological evaluation and measurements for ATP production, and secretion of albumin and urea. In conclusion, the 3D bio-printed liver tissue was able to detect the toxicity of compounds that was, otherwise, undetected by 2D culture and conventionally used spheroids. These findings demonstrate a 3D bio-printed liver tissue with increased accuracy of hepatotoxicity prediction in the early stages of drug discovery, as compared to currently available methods.