• Bulletin of the Korean Chemical Society
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• v.34 no.11
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• pp.3301-3306
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• 2013

This paper aims to address the cellular toxicity of ultra-pure titanium dioxide ($TiO_2$) and zinc oxide (ZnO) nanoparticles (NPs) frequently employed in sunscreens as inorganic physical sun blockers to provide protection against adverse effects of ultraviolet (UV) radiation including UVB (290-320 nm) and UVA (320-400 nm). In consideration that the production and the use of inorganic NPs have aroused many concerns and controversies regarding their safety and toxicity and that microsized $TiO_2$ and ZnO have been increasingly replaced by $TiO_2$ and ZnO NPs (< 100 nm), it is very important to directly investigate a main problem related to the intrinsic/inherent toxicity of these NPs and/or their incompatibility with biological objects. In the present study, we took advantage of the laser-assisted method called laser ablation for generation of $TiO_2$ and ZnO NPs. NPs were prepared through a physical process of irradiating solid targets in liquid phase, enabling verification of the toxicity of ultra-pure NPs with nascent surfaces free from any contamination. Our results show that $TiO_2$ NPs are essentially non-poisonous and ZnO NPs are more toxic than $TiO_2$ NPs based on the cell viability assays.

• Journal of the Korean Institute of Gas
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• v.18 no.4
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• pp.1-7
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• 2014

To protect the workers' health, we evaluated the hazards of gasoline which the large amounts of use and lack of information, and perform the risk assessment through the measurement of working environment. It is estimated the reproductive toxicity, and has germ cell mutagenicity class 1B, also IARC 2B, ACGIH A3 with carcinogenicity. With working environment, it is measured as below the TLV-TWA $900mg/m^3$. It is also calculated $0.3mg/m^3$ as carcinogenicity RfC (worker), $2.7mg/m^3$ as chronic inhalation toxicity RfC (worker), $2.7mg/m^3$ as developmental toxicity RfC (worker). From all of these results, it is calculated that the risks are 459, 51 and 51 as carcinogenicity, chronic inhalation toxicity and developmental toxicity, respectively. It is concluded that the risk of gasoline is evaluated over 1.

• Journal of the Korea Safety Management & Science
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• v.14 no.1
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• pp.43-51
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• 2012

This study was carried out to observe the impacts of a mouse's inhalation of toxic gas SO2 generated from combustion on its organs by different concentrations. As for research methods: First, after concentrations of SO2 generation from combustion had been set to three: low (10.4 ppm), middle (24.9 ppm) and high (122 ppm) through Gas Toxicity Testing Method (KS F 2271) and SO2 combustion gas was exposed to eight mice in each concentration. Five mice that were able to move based on LD50, a criterion, which sets the down time of a mouse's average behaviors to over 9 minutes, were randomly selected in each concentration, and they were set up as the subjects of the study on toxicity bio-markers. Second, tissues were taken from heart, liver, lungs, spleen and the thymus gland of the mice selected in each concentration and a pathological examination of them was carried out. As a result, microvascular congestion appeared in the heart, and cell necrosis, cortex congestion and tubule medulla congestion, etc. in each concentration were observed in addition to vascular congestion in liver, lungs, spleen and the thymus gland. Also, it was found that the higher the concentrations of SO2 exposure is, the greater, the changes in the organs get. Through this study, SO2 of various toxic gases generated from fire turned out to affect the tissues of each organ of a mouse, it is expected that the toxic gases may greatly affect human body in case of actual fire, and this study is evaluated as having a significance as a basic data on inhalation toxicity assessment of toxic substances generated in combustion.

• Toxicological Research
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• v.28 no.4
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• pp.217-224
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• 2012

In recent decades, titanium dioxide ($TiO_2$) nanoparticles have been used in various applications, including paints, coatings, and food. However, data are lacking on the toxicological aspects associated with their use. The aim of this study was to assess the inhalation toxicity of $TiO_2$ nanoparticles in rats by using inhalation exposure. Male Wistar rats were exposed to $TiO_2$ nanoparticles for 2 weeks (6 hr/day, 5 days/week) at a mean mass concentration of $11.39{\pm}0.31mg/m^3$. We performed time-course necropsies at 1, 7, and 15 days after exposure. Lung inflammation and injury were assessed on the basis of the total and individual cell counts in bronchoalveolar lavage fluid (BALF), and by biochemical assays, including an assay for lactate dehydrogenase (LDH). Furthermore, histopathological examination was performed to investigate the lungs and nasal cavity of rats. There were no statistically significant changes in the number of BALF cells, results of biochemical assays of BALF and serum, and results of cytokine analysis. However, we did observe histopathological changes in the nasal cavity tissue. Lesions were observed at post-exposure days 1 and 7, which resolved at post-exposure day 15. We also calculated the actual amounts of $TiO_2$ nanoparticles inhaled by the rats. The results showed that the degree of toxicity induced by $TiO_2$ nanoparticles correlated with the delivered quantities. In particular, exposure to small particles with a size of approximately 20 nm resulted in toxicity, even if the total particle number was relatively low.

• Toxicological Research
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• v.33 no.4
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• pp.305-313
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• 2017

Accumulating epidemiological evidence indicates that exposure to fine air pollution particles (APPs) is associated with a variety of adverse health effects. However, the exact physiochemical properties and biological toxicities of fine APPs are still not well characterized. We collected four types of fine particle (FP) (diesel exhaust particles [DEPs], natural organic combustion [NOC] ash, synthetic organic combustion [SOC] ash, and yellow sand dust [YSD]) and investigated their physicochemical properties and in vitro biological toxicity. DEPs were almost entirely composed of ultrafine particles (UFPs), while the NOC, SOC, and YSD particles were a mixture of UFPs and FPs. The main elements in the DEPs, NOC ash, SOC ash, and YSD were black carbon, silicon, black carbon, and silicon, respectively. DEPs exhibited dose-dependent mutagenicity even at a low dose in Salmonella typhimurium TA 98 and 100 strains in an Ames test for genotoxicity. However, NOC, SOC, and YSD particles did not show any mutagenicity at high doses. The neutral red uptake assay to test cell viability revealed that DEPs showed dose-dependent potent cytotoxicity even at a low concentration. The toxicity of DEPs was relatively higher than that of NOC, SOC, and YSD particles. Therefore, these results indicate that among the four FPs, DEPs showed the highest in vitro biological toxicity. Additional comprehensive research studies such as chemical analysis and in vivo acute and chronic inhalation toxicity tests are necessary to determine and clarify the effects of this air contaminant on human health.

• Journal of Environmental Health Sciences
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• v.50 no.3
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• pp.201-211
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• 2024

Background: Organic ultraviolet (UV) filters are widely used in sunscreen products and have been identified as an emerging contaminant. Organic UV filters co-exist with multiple components, but their mixture toxicity remains largely unknown. Objectives: We investigated the toxicity of single and binary mixtures of commonly used UV-filters using the human adrenocarcinoma (H295R) cell line. Methods: After exposure to non-cytotoxic concentrations of avobenzone (AVO), homosalate (HS), octisalate (OS), octinoxate (OMC), and octocrylene (OC), the levels of testosterone (T) and 17β-estradiol (E2) were measured. The median effective concentration (EC₅₀) values for the E2 of the individual substances were used to determine the mixture effect of four binary combinations: OMC+AVB, OMC+HS, OMC+OS, and OMC+OC. The synergistic, additive, and antagonistic effects of the mixture were determined by calculating toxic units (TU). To examine the mechanism of mixture toxicity, eight genes involved in steroidogenesis were analyzed using the real-time polymerase chain reaction. Results: The significant increase in E2 in H295R cells exposed to AVO, HS, OS, OMC, and OC suggest an estrogenic effect of the tested UV-filters. A significant decrease in T was observed in cells exposed to HS and OS. EC₅₀ values for E2 increase were 105 nM for AVO, 110 nM for HS, 120 nM for OS, 55 nM for OMC, and 80 nM for OC. Both binary mixtures consisting of OMC+HS and OMC+OS have synergistic effects. Conclusions: Our results showed that five types of UV-filter substances increase E2 in H295R cells. We examined the mixture toxicity in terms of increased estrogenicity and confirmed that E2 significantly increased when OMC was mixed with a salicylate-based UV-filters. These findings highlight the importance of determining the impact of UV filter mixtures.

• Nutrition Research and Practice
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• v.8 no.6
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• pp.613-617
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• 2014

BACKGROUND/OBJECTIVES: Adipogenesis is part of the cell differentiation process in which undifferentiated fibroblasts (pre-adipocytes) become mature adipocytes with the accumulation of lipid droplets and subsequent cell morphological changes. Several transcription factors and food components have been suggested to be involved in adipogenesis. The aim of this study was to determine whether mulberry leaf ethanol extract (MLEE) affects adipogenesis in 3T3-L1 adipocytes. MATERIALS/METHODS: The 3T3-L1 adipocytes were treated with different doses of MLEE for 8 days starting 2 days post-confluence. Cell viability, fat accumulation, and adipogenesis-related factors including CCAAT-enhancer-binding protein alpha ($C/EBP{\alpha}$), peroxisome proliferator-activated receptor gamma ($PPAR{\gamma}$), $PPAR{\gamma}$ coactivator 1 alpha (PGC-$1{\alpha}$), fatty acid synthase (FAS), and adiponectin were analyzed. RESULTS: Results showed that MLEE treatments at 10, 25, 50, and $100{\mu}g/ml$ had no effect on cell morphology and viability. Without evident toxicity, all MLEE treated cells had lower fat accumulation compared with control as shown by lower absorbances of Oil Red O stain. MLEE at 50 and $100{\mu}g/ml$ significantly reduced protein levels of $PPAR{\gamma}$, PGC-$1{\alpha}$, FAS, and adiponectin in differentiated adipocytes. Furthermore, protein level of $C/EBP{\alpha}$ was significantly decreased by the treatment of $100{\mu}g/ml$ MLEE. CONCLUSION: These results demonstrate that MLEE treatment has an anti-adipogenic effect in differentiated adipocytes without toxicity, suggesting its potential as an anti-obesity therapeutic.

• Journal of Microbiology and Biotechnology
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• v.28 no.5
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• pp.765-775
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• 2018

Using MCF7 breast cancer cells, we tested the anticancer activity of metabolites from 130 strains of myxobacteria newly isolated in South Korea. Of these, three strains whose metabolites had high anticancer activity and low cell toxicity were selected and identified by their fruiting body morphology, cell morphology, and 16S rRNA sequence. Strains KYC4030 and KYC4048 were determined to be Myxococcus fulvus, whereas strain KYC4081 was identified as Corallococcus coralloides. We found that metabolites of M. fulvus KYC4048 demonstrated no toxicity in normal cells but specifically induced cancer cell death by suppressing the expression of WNT2B. This discovery highlights the value of assessing the metabolic and biomedical potential of myxobacteria, even those that are already known but were isolated from new areas, and the possible use of metabolites from M. fulvus KYC4048 in cancer treatment.

• Restorative Dentistry and Endodontics
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• v.38 no.4
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• pp.204-209
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• 2013

Objectives: The objective of this in vitro study was to evaluate and compare the cytotoxicity of four different root canal sealers i.e. Apexit Plus (Ivoclar Vivadent), Endomethasone N (Septodont), AH-26 (Dentsply) and Pulpdent Root Canal Sealer (Pulpdent), on a mouse fibroblast cell line (L929). Materials and Methods: Thirty two discs for each sealer (5 mm in diameter and 2 mm in height) were fabricated in Teflon mould. The sealer extraction was made in cell culture medium (Dulbecco's Modified Eagle's Medium, DMEM) using the ratio 1.25 $cm^2/mL$ between the surface of the sealer samples and the volume of medium in a shaker incubator. Extraction of each sealer was obtained at 24 hr, 7th day, 14th day, and one month of interval. These extracts were incubated with L929 cell line and 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide (MTT) assay was done. Two-way ANOVA for interaction effects between sealer and time and Post-hoc multiple comparison using Tukey's test across all the 16 different groups were used for statistical analysis. Results: Apexit Plus root canal sealer was significantly less toxic than other sealers (p < 0.05) and showed higher cellular growth than control. Endomethasone N showed mild cytotoxicity. AH-26 showed severe toxicity which became mild after one month while Pulpdent Root Canal Sealer showed severe to moderate toxicity. Conclusions: Apexit Plus was relatively biocompatible sealer as compared to other three sealers which were cytotoxic at their initial stages, however, they became biocompatible with time.

• Toxicological Research
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• v.12 no.2
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• pp.203-211
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• 1996

Methanol has been widely used as an industrial solvent and environmental exposure to methanol would be expected to be increasing. In humans, methanol causes metabolic acidosis and damage to ocular system, and can lead to death in severe and untreated case. Clinical symptoms are attributed to accumulation of forrnic acid which is a metabolic product of methanol. In humans and primates, formic acid is accumulated after methanol intake but not in rodents due to the rapid metabolism of methanol. Neverthless, the developmental and reproductive toxicity were reported in rodents. Previous reports showed that perinatal exposure to ethanol produces a variety of damage in human central nervous system by direct neurotoxicity. This suggests that the mechanism of toxic symptoms by methanol in rodents might mimic that of ethanol in human. In the present study I hypothesized that methanol can also induce toxicity in neuronal cells. For the study, primary culture of rat hippocampal neurons and glias were empolyed. Hippocampal cells were prepared from the embryonic day-17 fetuses and maintained up to 7 days. Effect of methanol (10, 100, 500 and 1000 mM) on neurite outgrowth and cell viability was investigated at 0, 18 and 24 hours following methanol treatment. To study the changes in proliferation of glial cells, protein content was measured at 7 days. Neuronal cell viability in culture was not altered during 0-24 hours after methanol treatment. 10 and 100 mM methanol treatment significantly enhanced neurite outgrowth between 18-24 hours. 7-day exposure to 10 or 100 mM methanol significantly increased protein contents but that to 1000 mM methanol decreased in culture. In conclusion, methanol may have a variety of effects on growing and differentiation of neurons and glial cells in hippocampus. Treatment with low concentration of methanol caused that neurite outgrowth was enhanced during 18-24 hours and the numbers of glial cell were increased for 7 days. High concentration of methanol brought about decreased protein contents. At present, the mechanism responsible for the methanol- induced enhancement of neurite outgrowth is not clear. Further studies are required to delineate the mechanism possibly by employing molecular biological techniques.