The oxidative stress-dependent pulmonary inflammation of inhalable multi-walled carbon nanotube-containing nano-concrete dust and its comparison with conventional concrete dust and DQ12.

Nano-concrete, which is an admixture of nanomaterials in concrete recipes, has been investigated to overcome the limitations of existing concrete, such as its stability and strength. However, there is no information on the human health effects of broken-down dust released during the construction and demolition efforts. In this study, we prepared an inhalable fraction of multi-walled carbon nanotube-containing nano-concrete dust and performed comparative toxicity studies with conventional concrete dust and DQ12 using a rat intratracheal instillation model. Although the recipes for concrete and nano-concrete are entirely different, the pulverized dust samples showed similar physicochemical properties, such as 0.46-0.48 µm diameter and chemical composition. Both concrete and nano-concrete dust exhibited similar patterns and magnitudes, representing acute neutrophilic inflammation and chronic active inflammation with lymphocyte infiltration. The toxicity endpoints of the tested particles at both time points showed an excellent correlation with the reactive oxygen species levels released from the alveolar macrophages, highlighting that alveolar macrophages are the primary target cells and that the oxidative stress paradigm is the main toxicity mechanism of the tested particles. In addition, the toxicity potentials of both concrete and nano-concrete dust were more than 10 times lower than that of DQ12.

Differential particle and ion kinetics of silver nanoparticles in the lungs and biotransformation to insoluble silver sulfide.

The measurement of nanoparticles (NPs) in a biological matrix is essential in various toxicity studies. However, the current knowledge has limitations in differentiating particulate and ionic forms and further identification of their biotransformation. Herein, we evaluate the biotransformation and differential lung clearance kinetics of particulate and ionic forms using PEGylated silver NPs (AgNP-PEGs; 47.51 nm) and PEGylated gold NPs (AuNP-PEGs; 11.76 nm). At 0, 3, and 6 h and 1, 3, 7, and 14 days after a single pharyngeal aspiration in mice at 25 µg/mouse, half of the lung is digested by proteinase K (PK) to separate particulates and ions, and the other half is subjected to the acid digestion method for comparison. The quantitative and qualitative evaluation of lung clearance kinetics suggests that AgNP-PEGs are quickly dissolved and transformed into insoluble silver sulfide (Ag2S), which shows a fast-clearing early phase (0 -6 h; particle T1/2: 4.8 h) and slow-clearing late phase (1 -14 days; particle T1/2: 13.20 days). In contrast, AuNP-PEGs were scarcely cleared or biotransformed in the lungs for 14 days. The lung clearance kinetics of AgNPs and biotransformation shown in this study can be informed by the PK digestion method and cannot be obtained using the acid digestion method.

Preliminary Study on an Alternative Test Method with MCTT HCETM for Ocular Irritation Test of Ophthalmic Medical Devices.

The sustained growth of the market for ophthalmic medical devices has increased the demand for alternatives to animal testing for the evaluation of eye irritation. The International Organization for Standardization has acknowledged the need to develop novel in vitro tests to replace animal testing. Here, we evaluated the applicability of an alternative method based on a human corneal model to test the safety of ophthalmic medical devices. 2-Hydroxyethyl methacrylate (HEMA) and Polymethyl methacrylate (PMMA), which are used to fabricate contact lenses, were used as base materials. These materials were blended with eye irritant and non-irritant chemicals specified in the OECD Test Guideline (TG) 492 and Globally Harmonized System (GHS) classification. Then, three GLP-certified laboratories performed three replicates using the developed method using 3D reconstructed human cornea epithelium, MCTT HCETM. OECD TG 492 describes the procedure used to evaluate the eye hazard potential of the test chemical based on its ability to induce cytotoxicity in a reconstructed human cornea-like epithelium (RhCE) tissue. Results: The within-laboratory reproducibility (WLR) and between-laboratory reproducibility (BLR) were both 100%. When a polar extraction solvent was used, the sensitivity, specificity, and accuracy were all 100% in each laboratory. When a non-polar extraction solvent was used, the sensitivity was 80%, the specificity was 100%, and the accuracy was 90%. The proposed method exhibited excellent reproducibility and predictive capacity within and between laboratories. Therefore, the proposed method using the MCTT HCETM model could be used to evaluate eye irritation caused by ophthalmic medical devices.

Pharmacokinetics and toxicity evaluation following oral exposure to bisphenol F.

Bisphenol F is a substitute material for bisphenol A and is widely used in household products as a raw material for polycarbonate resin, epoxy resin, and plastic reinforcement. It is known to be mainly used in food containers, thermal paper for receipts, and coatings for water pipes. In some countries, bisphenol F has been detected in drinking water and human urine samples. However, due to the lack of safety evaluation data on bisphenol F, it is difficult to establish appropriate guidelines for the proper use of the substance, and social anxiety is increasing accordingly. This study investigated the use, exposure route, and distribution flow of bisphenol F, a household chemical. To determine the no-observed-adverse-effect level (NOAEL) and target organ of bisphenol F after exposure, a single-dose oral toxicity, dose-range finding (28 day oral), repeated dose toxicity (90 day oral), and genotoxicity (reverse mutation, chromosomal abnormality, in vivo micronucleus test) tests were performed. The pharmacokinetic profile was also obtained. The test results are as follows: in the pharmacokinetic study, it was confirmed that single oral exposure to BPF resulted in systemic exposure; in single oral dose toxicity test, the approximate lethal dose was found to be 4000 mg/kg and confusion and convulsion was shown in the test animals; NOAEL was determined to be 2 mg/kg/day for male and 5 mg/kg/day for female, and the no-observed-effect level (NOEL) was determined to be 2 mg/kg/day for males and 1 mg/kg/day for females, and the target organ was the small intestine; genotoxicity tests confirmed that BPF does not induce genotoxicity.

Evaluation of the acute, sub-chronic and chronic oral toxicity, genetic toxicity, and safety of a Lomens-P0.

Extracts of Hordeum vulgare and Chrysanthemum zawadskii, two traditional herbal medicines, have long been used to treat women's diseases. Our previous studies have confirmed that these extracts could help relieve the symptoms of premenstrual syndrome by inhibiting prolactin release. A mixture of these natural products was named Lomens-P0. In this study, we conducted three genotoxicity tests (bacterial reverse mutation, mammalian chromosome aberration, and mammalian erythrocyte micronucleus studies) and four oral toxicity tests (single-dose, 2-week repeated-dose, and 13-week repeated-dose studies in rodents, and a single-dose dose-escalation toxicity study in a non-rodent model) to confirm the potential toxicity and safety of Lomens-P0. The results of this series of tests indicated Lomens-P0 did not induce genotoxicity, and the NOAEL for the rodent was 2000 mg/kg BW/day. Similarly, no toxic effects were evident in the single-dose-escalation study in the non-rodent model. In conclusion, we confirmed that Lomens-P0 might have potential utility as a raw material for nutraceuticals and natural medicines. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s43188-021-00090-5.

Inhalation toxicity of polystyrene micro(nano)plastics using modified OECD TG 412.

Recently, there have been reports that many microplastics are found in the air, which has raised concerns about their toxicity. To date, however, only limited research has investigated the effects of micro(nano)plastics on human health, and even less the potential for inhalation toxicity. To fill this research gap, we investigated the potential inhalation toxicity of micro(nano)plastics using a modified OECD Guideline for Testing of Chemicals No. 412 '28-Day (subacute) inhalation toxicity study' using a whole-body inhalation system. Sprague-Dawley rats were exposed to three different exposure concentrations of polystyrene micro(nano)plastics (PSMPs), as well as control, for 14 days of inhalation exposure. After 14 days, alterations were observed on sevral endpoints in physiological, serum biochemical, hematological, and respiratory function markers measured on the samples exposed to PSMPs. However, no concentration-response relationships were observed, suggesting that these effects may not be definitively linked to exposure of PSMPs. On the other hand, the expression of inflammatory proteins (TGF-ß and TNF-α) increased in the lung tissue in an exposure concentration-dependent manner. The overall results indicate that 14-day inhalation exposure of PSMPs to rats has a more pronounced effect at the molecular level than at the organismal one. These results suggest that if the exposure sustained, alterations at the molecular level may lead to subsequent alterations at the higher levels, and consequently, the health risks of inhalation exposed micro(nano)plastics should not be neglected.

Toxicity assessment of Gryllus bimaculatus (a type of cricket) glycosaminoglycan.

We performed general toxicity studies of Gryllus bimaculatus (two-spotted cricket) glycosaminoglycan (GbG), including a single, 4-week repeated oral dose toxicity test in ICR mice, and short-term genotoxicity tests. The mutagenic potential of the purified GbG was non-genotoxic when it was evaluated using short-term genotoxicity tests, namely Ames, chromosome aberration (CA), and micronuclei (MN) tests. In Salmonella typhimurium and Escherichia coli assays, GbG did not produce any mutagenic response in the absence or presence of S9 mix with five bacterial strains (TA98, TA100, TA1535, TA1537, and WP2uvrA). Chromosome aberration test showed that GbG had no significant effect on Chinese hamster ovary (CHO) cells. In mouse micronuclei tests after twice oral treatments per day for two days, no significant alteration in the occurrence of micronucleated polychromatic erythrocytes was observed in ICR male mice intraperitoneally administered with GbG at doses of 15.63, 31.25, or 62.50 mg/kg. These results indicate that GbG has no mutagenic potential in these in vitro and in vivo systems. After GbG was orally administered at doses of 20, 40, 80, and 160 mg/kg for a single oral dose toxicity study and at 0, 40, 80, and 160 mg/kg bw/day for 4-week oral dose toxicity study, there were no observed clinical signs or deaths related to treatment in any group tested. Therefore, the approximate lethal oral dose of GbG was considered to be higher than 160 mg/kg in mice. Throughout the administration period, no significant changes in diet consumption, ophthalmologic findings, organ weight, clinical pathology (hematology, clinical chemistry, coagulation, and urinalysis), or gross pathology were detected. Microscopic examination did not identify any treatment-related histopathologic changes in organs of GbG-treated mice in the high dose group. These results indicate that the no-observed adverse effect level (NOAEL) of GbG is higher than 160 mg/kg bw/day in mice.

Carbon nanomaterial-derived lung burden analysis using UV-Vis spectrophotometry and proteinase K digestion.

BACKGROUND: The quantification of nanomaterials accumulated in various organs is crucial in studying their toxicity and toxicokinetics. However, some types of nanomaterials, including carbon nanomaterials (CNMs), are difficult to quantify in a biological matrix. Therefore, developing improved methodologies for quantification of CNMs in vital organs is instrumental in their continued modification and application. RESULTS: In this study, carbon black, nanodiamond, multi-walled carbon nanotube, carbon nanofiber, and graphene nanoplatelet were assembled and used as a panel of CNMs. All CNMs showed significant absorbance at 750 nm, while their bio-components showed minimal absorbance at this wavelength. Quantification of CNMs using their absorbance at 750 nm was shown to have more than 94% accuracy in all of the studied materials. Incubating proteinase K (PK) for 2 days with a mixture of lung tissue homogenates and CNMs showed an average recovery rate over 90%. The utility of this method was confirmed in a murine pharyngeal aspiration model using CNMs at 30 µg/mouse. CONCLUSIONS: We developed an improved lung burden assay for CNMs with an accuracy > 94% and a recovery rate > 90% using PK digestion and UV-Vis spectrophotometry. This method can be applied to any nanomaterial with sufficient absorbance in the near-infrared band and can differentiate nanomaterials from elements in the body, as well as the soluble fraction of the nanomaterial. Furthermore, a combination of PK digestion and other instrumental analysis specific to the nanomaterial can be applied to organ burden analysis.

Oral toxicity of titanium dioxide P25 at repeated dose 28-day and 90-day in rats.

BACKGROUND: Nanotechnology is indispensable to many different applications. Although nanoparticles have been widely used in, for example, cosmetics, sunscreen, food packaging, and medications, they may pose human safety risks associated with nanotoxicity. Thus, toxicity testing of nanoparticles is essential to assess the relative health risks associated with consumer exposure. METHODS: In this study, we identified the NOAEL (no observed adverse effect level) of the agglomerated/aggregated TiO2 P25 (approximately 180 nm) administered at repeated doses to Sprague-Dawley (SD) rats for 28 and 90 days. Ten of the 15 animals were necropsied for toxicity evaluation after the repeated-dose 90-day study, and the remaining five animals were allowed to recover for 28 days. The agglomerated/aggregated TiO2 P25 dose levels used included 250 mg kg- 1 d- 1 (low), 500 mg kg- 1 d- 1 (medium), and 1000 mg kg- 1 d- 1 (high), and their effects were compared with those of the vehicle control. During the treatment period, the animals were observed for mortality, clinical signs (detailed daily and weekly clinical observations), functional observation battery, weekly body weight, and food and water consumption and were also subjected to ophthalmological examination and urinalysis. After termination of the repeated-dose 28-day, 90-day, and recovery studies, clinical pathology (hematology, blood coagulation time, and serum biochemistry), necropsy (organ weights and gross findings), and histopathological examinations were performed. RESULTS: No systemic toxicological effects were associated with the agglomerated/aggregated TiO2 P25 during the repeated-dose 28-day, 90-day, and recovery studies in SD rats. Therefore, the NOAEL of the agglomerated/aggregated TiO2 P25 was identified as 1000 mg kg- 1 d- 1, and the substance was not detected in the target organs. CONCLUSION: Subacute and subchronic oral administration of the agglomerated/aggregated TiO2 P25 was unlikely to cause side effects or toxic reactions in rats.

Potential Role of Soluble Metal Impurities in the Acute Lung Inflammogenicity of Multi-Walled Carbon Nanotubes.

Multi-walled carbon nanotubes (MWCNTs) have variable metal impurities, but little is known about the impact of soluble metal impurities on the toxicity of MWCNTs. Here, we evaluated the role of soluble metal impurities to the acute inflammogenic potential of MWCNTs, using five types of high purity MWCNTs (>95%). MWCNTs and their soluble fractions collected at 24 h after incubation in phosphate-buffered saline showed diverse metal impurities with variable concentrations. The fiber-free soluble fractions produced variable levels of reactive oxygen species (ROS), and the iron level was the key determinant for ROS production. The acute inflammation at 24 h after intratracheal instillation of MWCNTs to rats at 0.19, 0.63, and 1.91 mg MWCNT/kg body weight (bw) or fiber-free supernatants from MWCNT suspensions at 1.91 and 7.64 mg MWCNT/kg bw showed that the number of granulocytes, a marker for acute inflammation, was significantly increased with a good dose-dependency. The correlation study showed that neither the levels of iron nor the ROS generation potential of the soluble fractions showed any correlations with the inflammogenic potential. However, the total concentration of transition metals in the soluble fractions showed a good correlation with the acute lung inflammogenic potential. These results implied that metal impurities, especially transitional metals, can contribute to the acute inflammogenic potential of MWCNTs, although the major parameter for the toxicity of MWCNTs is size and shape.

Toxicological Evaluation of Saposhnikoviae Radix Water Extract and its Antihyperuricemic Potential.

Although the dried root of Saposhnikovia divaricata (Turcz.) Schischk. (Umbelliferae) is a popular medicinal plant in East Asia, there has been no systemic toxicological evaluation of a water extract of Saposhnikoviae Radix (SRE). In this experiment, an oral acute and 13-week subchronic toxicological evaluations of SRE (500-5,000 mg/ kg body weight) were performed in both sexes of Crl:CD(SD) rats. Based on the results from mortality, clinical signs, effects on body weight and organ weight, clinical biochemistry, hematology, urinalysis, and histopathology, significant acute, 4-week repeated dose range finding (DRF) and 13-week subchronic toxicity of SRE was not observed in either sex of rats; thus, the no observed adverse effect level (NOAEL) was 5,000 mg (kg/day). To identify anti-hyperuricemia potential of SRE, the suppressive effect of SRE was determined in mice challenged with potassium oxonate (PO; 250 mg/kg) via intraperitoneal injection for 8 days (each group; n = 7). SRE supplementation suppressed the uric acid level in urine through significant xanthine oxidase (XO) inhibitory activity. Kidney dysfunctions were observed in PO-challenged mice as evidenced by an increase in serum creatinine level. Whereas, SRE supplementation suppressed it in a dose-dependent manner. Collectively, SRE was safe up to 5,000 mg (kg/day) based on NOAEL found from acute and 13-week subchronic toxicological evaluations. SRE had anti-hyperuricemia effect and lowered the excessive level of uric acid, a potential factor for gout and kidney failure.

Derivation of occupational exposure limits for multi-walled carbon nanotubes and graphene using subchronic inhalation toxicity data and a multi-path particle dosimetry model.

In this study, we aimed to provide the recommended occupational exposure limits (OELs) for multi-walled carbon nanotubes (MWCNTs) and graphene nanomaterials based on data from a subchronic inhalation toxicity study using a lung dosimetry model. We used a no observed adverse effect level (NOAEL) of 0.98 mg m-3 and 3.02 mg m-3 in rats for MWCNTs and graphene, respectively. The NOAELs were obtained from a 13-week inhalation study in rats. The deposition fractions of MWCNTs and graphene in the respiratory tract of rats and humans were calculated by using the multi-path particle dosimetry model (MPPD model, v3.04). The deposition fraction in the alveolar region was 0.0527 and 0.0984 for MWCNTs and 0.0569 and 0.1043 for graphene in rats and human lungs, respectively. Then, the human equivalent exposure concentrations (HECs) of MWCNTs and graphene were calculated according to the method by the National Institute for Occupational Safety and Health (NIOSH). The HEC was estimated to be 0.17 mg m-3 for MWCNTs and to be 0.54 mg m-3 for graphene, which was relevant to the rat NOAEL of 0.98 mg m-3 and 3.02 mg m-3 for MWCNTs and graphene, respectively. Finally, we estimated the recommended OELs by applying uncertainty factors (UFs) to the HEC as follows: an UF of 3 for species differences (rats to humans), 2 for an experimental duration (subchronic to chronic), and 5 for inter-individual variations among workers. Thus, the OEL was estimated to be 6 µg m-3 for MWCNTs and 18 µg m-3 for graphene. These values could be useful in preventing the adverse health effects of nanoparticles in workers.

Ginsenosides Rg5 and Rk1 Enriched Cultured Wild Ginseng Root Extract Bioconversion of Pediococcus pentosaceus HLJG0702: Effect on Scopolamine-Induced Memory Dysfunction in Mice.

Wild ginseng is known to contain additional physiologically and pharmacologically active substances than common ginseng. The utilization of this herb can be maximized by altering its composition via tissue culture generating adventitious roots. We enriched the content of specific ginsenosides and investigated their role in ameliorating memory impairment. Cultured wild ginseng root was subjected to extraction, steaming, and fermentation using Pediococcus pentosaceus HLJG0702 to enhance the levels of ginsenosides Rg5 /Rk1. The analysis of product, HLJG0701, confirmed target ginsenosides. We analyzed the inhibitory effect of ginsenoside Rg5/Rk1, HLJG0701 and the raw material on acetylcholinesterase. Further, we performed Morris water maze, Y-maze, and passive avoidance tasks with mice exhibiting memory deficit induced by scopolamine, and we analyzed the concentrations of acetylcholinesterase and acetylcholine in their brains. Studies showed that the levels of ginsenosides Rg5 /Rk1, not found in the raw material, were enhanced in HLJG0701. Ginsenosides and HLJG0701 significantly inhibited acetylcholinesterase unlike the raw material. In all behavioral tasks, HLJG0701 showed memory improvement. It reduced acetylcholinesterase, whereas, it preserved acetylcholine in brain. In conclusion, cultured wild ginseng root extract fermented by P. pentosaceus HLJG0702 contains the distinctive ginsenosides Rg5/Rk1, which may ameliorate memory impairment via inhibition of acetylcholinesterase resulting in increased acetylcholine levels in the brain.

Threshold Rigidity Values for the Asbestos-like Pathogenicity of High-Aspect-Ratio Carbon Nanotubes in a Mouse Pleural Inflammation Model.

The qualitative and quantitative evaluation of the physicochemical parameters associated with the pathogenicity of high-aspect-ratio nanomaterials is important for comprehensive regulation efforts and safety-by-design approaches. Here, we report quantitative data on the correlations between the rigidity of these nanomaterials and toxicity endpoints in vitro and in vivo. As measured by new ISO standards published in 2017, rigidity shows a strong positive correlation with inflammogenic potential, as indicated by inflammatory cell counts and IL-1ß (a biomarker for frustrated phagocytosis) levels in both the acute and chronic phases. In vitro experiments using differentiated THP-1 cells find that only highly rigid multiwalled carbon nanotubes (MWCNTs) and asbestos fibers lead to piercing and frustrated phagocytosis. Thus, this study suggests a bending ratio of 0.97 and a static bending persistence length of 1.08 as threshold rigidity values for asbestos-like pathogenicity. However, additional research using MWCNTs with rigidity values that lie between those of non-inflammogenic ( Db = 0.66 and SBPL = 0.87) and inflammogenic fibers ( Db = 0.97 and SBPL = 1.09) is required to identify more accurate threshold values, which would be useful for comprehensive regulation and safety-by-design approaches based on MWCNTs.

Tissue distribution of gold and silver after subacute intravenous injection of co-administered gold and silver nanoparticles of similar sizes.

Gold (AuNPs, 12.8 nm) and silver nanoparticles (AgNPs, 10 nm), mixed or separate, were injected into the caudal vein of male Sprague-Dawley rats for 4 weeks. The rats were allowed to recover for further 4 weeks to examine the differences in AuNP/AgNP tissue distribution and clearance. The size distribution of injected AuNPs and AgNPs were not statistically different. The dose groups (five males per group for the administration and three males for the recovery) consisted of seven divisions, i.e., control, AgNPs (with a low dose of 10 µg/kg/day, and, a high dose of 100 µg/kg/day), AuNPs (with a low dose of 10 µg/kg/day, and, a high dose of 100 µg/kg/day), as well as mixed AgNPs/AuNPs (with a low dose of 10/10 µg/kg/day, and a high dose of 100/100 µg/kg/day). The AgNPs accumulated in a dose-dependent manner in the liver, spleen, kidneys, lung, brain, testis or blood. Au concentration increased also in a dose-dependent manner in the liver, kidneys, spleen and lungs, but not in the brain, testis and blood. Ag concentration in the tissues increased dose-dependently after 4 weeks of AgNP/AuNP mixed administration, but to a much lower extent than those observed when they were administered separately. Ag concentration in the tissues after 4 weeks of AgNP/AuNP mixed administration cleared dose-dependently after 4 weeks of recovery. Au concentration in the tissues increased dose-dependently after 4 weeks of AgNp/AuNP mixed administration, while Au concentration in the tissues did not clear as seen in Ag after 4 weeks recovery. Au concentration showed biopersistency or accumulation in the liver, kidneys, spleen and brain of the 4 weeks of recovery. In conclusion, AgNPs and AuNPs showed different toxicokinetic properties and the mixed administration of AgNPs with AuNPs resulted in mutual reduction of their tissue distribution which appeared to be due to competitive inhibition. Furthermore, this subacute intravenous injection study has suggested that these nanoparticles were distributed to the organs in particulate instead of ionic forms.

Inhalation toxicity of indoor air pollutants in Drosophila melanogaster using integrated transcriptomics and computational behavior analyses.

We conducted an inhalation toxicity test on the alternative animal model, Drosophila melanogaster, to investigate potential hazards of indoor air pollution. The inhalation toxicity of toluene and formaldehyde was investigated using comprehensive transcriptomics and computational behavior analyses. The ingenuity pathway analysis (IPA) based on microarray data suggests the involvement of pathways related to immune response, stress response, and metabolism in formaldehyde and toluene exposure based on hub molecules. We conducted a toxicity test using mutants of the representative genes in these pathways to explore the toxicological consequences of alterations of these pathways. Furthermore, extensive computational behavior analysis showed that exposure to either toluene or formaldehyde reduced most of the behavioral parameters of both wild-type and mutants. Interestingly, behavioral alteration caused by toluene or formaldehyde exposure was most severe in the p38b mutant, suggesting that the defects in the p38 pathway underlie behavioral alteration. Overall, the results indicate that exposure to toluene and formaldehyde via inhalation causes severe toxicity in Drosophila, by inducing significant alterations in gene expression and behavior, suggesting that Drosophila can be used as a potential alternative model in inhalation toxicity screening.

Oral Toxicity Study and Skin Sensitization Test of a Cricket.

Crickets have been attracting considerable interest in the field of nutrition and toxicology due to the global exhaustion of food resulting from a growing population. The cricket is normally eaten in several countries after roasting, similar to the grasshopper; however, safety evaluation data on cricket powder is limited. Here, we performed general toxicity studies of cricket powder including a single, 2-week repeated dose range evaluation test, a 13-week repeated oral dose toxicity test in Sprague-Dawley rats, a single oral dose toxicity test in Beagle dogs, and a skin sensitization test in guinea pigs following the Organization for Economic Cooperation and Development test guidelines 406 and 408 in addition to Good Laboratory Practice. To investigate the NOAEL and target organs of cricket powder, Sprague-Dawley rats were allocated to 4 groups: vehicle control, 1,250 mg/kg, 2,500 mg/kg, 5,000 mg/kg dose test groups and cricket powder was administered over 13 weeks after single dose and dose range finding studies in rats based on the results of the single oral administration toxicity study in rats and Beagle dogs. The results of the study showed that the NOAEL of cricket powder was over 5,000 mg/kg for both sexes of rats without adverse effects in a 13-week repeated oral toxicity study and there was no skin hypersensitivity reaction. Therefore, our results reveal that crickets can be widely used as a new substitute food or nutrient resource.

Multiwall Carbon Nanotube-Induced DNA Damage and Cytotoxicity in Male Human Peripheral Blood Lymphocytes.

Carbon nanotubes (CNTs) have been introduced recently as a novel carrier system for both small and large therapeutic molecules. Biotin-functionalized single-wall CNTs have been conjugated with the anticancer agent taxoid using a cleavable linker, and multiwall carbon nanotubes (MWCNTs) conjugated with iron nanoparticles have been efficiently loaded with doxorubicin. The MWCNTs are effective transporters for biological macromolecules and drugs to target cells and tissues, thereby attracting the attention of the biomedical industry. Administrating MWCNTs for medical application invariably involves intravenous administration and ultimate contact with human peripheral blood lymphocytes (HPBLs), yet toxicological studies on the effect of MWCNTs on HPBLs are lacking. Accordingly, this study evaluated the cytotoxic and genotoxic effects of MWCNTs on healthy male HPBLs. Healthy male HPBLs were treated with MWCNTs at 3 different concentrations (12.5, 25, and 50 µg/mL) for 48 hours. Under these conditions, the MWCNTs induced significant cell growth retardation, DNA damage, and cytotoxicity. The MWCNT-treated HPBLs also exhibited an increased intracellular reactive oxygen species level during the experimental period, which leads to cell damage and death, proliferation inhibition, DNA damage, and an inflammatory response.

Physicochemical analysis and repeated-dose 90-days oral toxicity study of nanocalcium carbonate in Sprague-Dawley rats.

In our previous studies of nanocalcium carbonate, in which we performed physicochemical analysis, genotoxicity, acute single-dose and repeated-dose 14-day oral toxicity testings in Sprague-Dawley (SD) rats, nanocalcium carbonate did not show a difference in toxicity compared to vehicle control. Here, we provide the first report of a repeated-dose 90-day oral toxicity test of nanocalcium carbonate in Sprague-Dawley rats, with physicochemical comparison of micro and nanocalcium carbonate. We find that the two particles differ in size, hydrodynamic size, and specific surface area, with no differences in components, crystalline structure and radical production. In terms of ionization ability, nanocalcium carbonate was slightly more ionized within 1% than microcalcium carbonate at pH 5 and pH 7. In the repeated-dose 90-day oral toxicity test of nanocalcium carbonate, there was no significant toxicity, and similar blood concentrations of Ca(2+) compared to the vehicle control group. Based on our results, although nanocalcium carbonate has different physicochemical properties, nanocalcium carbonate does not differ from microcalcium carbonate in terms of toxicity. Based on the results, we suggest that the no-observed-adverse-effect level (NOAEL) of nanocalcium carbonate is 1000 mg kg(-1) day(-1) in SD rats according to the maximum dose (OECD guideline 408). However, the NOAEL might be higher than 1000 mg kg(-1) day(-1) because there were no adverse effects revealed by consistent pathological findings or biochemical parameter changes. To justify a safe concentration of nanocalcium carbonate, which is a low toxicity chemical, more data is required on dose levels above 1000 mg kg(-1). Our findings may be useful for creating safety guidelines for the use nanocalcium carbonate.

Evaluation of in vitro and in vivo genotoxicity of single-walled carbon nanotubes.

Single-walled carbon nanotubes (SWCNTs) have extensive potential industrial applications due to their unique physical and chemical properties; yet this also increases the chance of human and environment exposure to SWCNTs. Due to the current lack of hazardous effect information on SWNCTs, a standardized genotoxicity battery test was conducted to clarify the genetic toxicity potential of SWCNTs (diameter: 1-1.2 nm, length: ∼20 µm) according to Organization for Economic Cooperation and Development test guidelines 471 (bacterial reverse mutation test), 473 (in vitro chromosome aberration test), and 474 (in vivo micronuclei test) with a good laboratory practice system. The test results showed that the SWCNTs did not induce significant bacterial reverse mutations at 31.3-500 µg/plate in Salmonella typhimurium strains TA98, TA100, TA1535, and TA1537 or in Escherichia coli strain WP2uvrA, with and without a metabolic activation system. Furthermore, the in vitro chromosome aberration test showed no significant increase in structural or numerical chromosome aberration frequencies at SWCNT dose levels of 12.5-50 µg/ml in the presence and absence of metabolic activation. However, dose-dependent cell growth inhibition was found at all the SWCNT dose levels and statistically significant cytotoxic effects observed at certain concentrations in the presence and absence of metabolic activation. Finally, the SWCNTs did not evoke significant in vivo micronuclei frequencies in the polychromatic erythrocytes of an imprinting control region mice at 25-100 mg/kg. Thus, according to the results of the present study, the SWCNTs were not found to have a genotoxic effect on the in vitro and in vivo test systems.