Mass spectrometry (MS)-based metabolomics of plasma and urine in dry eye disease (DED)-induced rat model.

Dry eye disease (DED) is an ophthalmic disease associated with poor quality and quantity of tears, and the number of patients is steadily increasing. The aim of this study was to determine plasma and urine metabolites obtained from DED scopolamine animal model where dry eye conditions (DRY) are induced. It was also of interest to examine whether DED (scopolamine) rat model was exacerbated by treatment with benzalkonium chloride (BAC). Subsequently, plasma and urine metabolites were analyzed using liquid chromatography (LC) and gas chromatography (GC)-mass spectrometry (MS), respectively. Data demonstrated that DED indicators such as tear volume, tear breakup time (TBUT), and corneal damage in the DED groups (DRY and BAC group) differed from those of control (CON). Similar results were noted in inflammatory factors such as interleukin (IL-1ß), IL-6, and tumor necrosis factor (TNF)-α. In the partial least squares-discriminant analysis (PLS-DA) score plots, the three groups were distinctly separated from each other. In addition, the related metabolites were also associated with these distinct separations as evidenced by 9 and 14 in plasma and urine, respectively. Almost all of the selected metabolites were decreased in the DRY group compared to CON, and the BAC group was lower than the DRY. In plasma and urine, lysophosphatidylcholine/lysophosphatidylethanolamine, organic acids, amino acids, and sugars varied between three groups, and these metabolites were related to inflammation and oxidative stress. Data suggest that treatment with scopolamine with/without BAC-induced DED and affected the level of systemic metabolites involved in inflammation and oxidative stress.

Safety assessment of cocamidopropyl betaine, a cosmetic ingredient.

Cocamidopropyl betaine (CAPB) is a surfactant derived from coconut oil that is widely used in cosmetics and personal products for several purposes, such as a surfactant, foam booster, mildness, and viscosity control. Cocamidopropyl betaine is used at concentrations up to 30% in cosmetics. The acute toxicity, skin irritation, eye irritation, skin sensitization, repeated dose toxicity, genotoxicity, carcinogenicity, and phototoxicity of cocamidopropyl betaine were evaluated. Cocamidopropyl betaine was observed to induce mild skin irritation, eye irritation and skin sensitization. The NOAEL of cocamidopropyl betaine was determined to be 250 mg/kg/day based on the results of a 92-day repeated-dose oral toxicity study in rats. The systemic exposure dose of cocamidopropyl betaine was estimated to range from 0.00120 to 0.93195 mg/kg/day when used in cosmetic products. The margin of safety of cocamidopropyl betaine was calculated to be greater than 100 when used at a maximum concentration of 6% in leave-on products and 30% in rinse-off products, suggesting that its use in cosmetic products is safe under current usage conditions.

Prediction of skin sensitization using machine learning.

As global awareness of animal welfare spreads, the development of alternative animal test models is increasingly necessary. The purpose of this study was to develop a practical machine-learning model for skin sensitization using three physicochemical properties of the chemicals: surface tension, melting point, and molecular weight. In this study, a total of 482 chemicals with local lymph node assay results were collected, and 297 datasets with 6 physico-chemical properties were used to develop Random Forest (RF) model for skin sensitization. The developed model was validated with 45 fragrance allergens announced by European Commission. The validation results showed that RF achieved better or similar classification performance with f1-scores of 54% for penal, 82% for ternary, and 96% for binary compared with Support Vector Machine (SVM) (penal, 41%; ternary, 81%; binary, 93%), QSARs (ChemTunes, 72% for ternary; OECD Toolbox, 89% for binary), and a linear model (Kim et al., 2020) (41% for penal), and we recommend the ternary classification based on Global Harmonized System providing more detailed and precise information. In the further study, the proposed model results were experimentally validated with the Direct Peptide Reactivity Assay (DPRA, OECD TG 442C approved model), and the results showed a similar tendency. We anticipate that this study will help to easily and quickly screen chemical sensitization hazards.

A Metabolomics Approach to Sulforaphane Efficacy in Secondhand Smoking-Induced Pulmonary Damage in Mice.

Sulforaphane is an isocyanate abundantly present in cruciferous vegetables. In the present study, we aimed to investigate the effects of sulforaphane on secondhand smoking (SHS)-induced pulmonary damage in mice. Additionally, a metabolomic study was performed to identify biomarkers associated with pulmonary disease using proton nuclear magnetic resonance (1H-NMR) analysis. Male C57BL6J mice were divided into a control group, an SHS exposure group (positive control group, PC), and a sulforaphane treatment group exposed to secondhand smoke (SS) (n = 5 per group). The PC and SS groups were exposed to secondhand smoke in a chamber twice daily for four weeks. Mice in the SS group were orally administered sulforaphane (50 mg/kg) for four weeks during secondhand smoke exposure. Histopathological examination of the lungs revealed pulmonary damage in PC mice, including loss of bronchial epithelial cells, bronchial wall thickening, and infiltration of macrophages. In contrast, mice in the SS group showed little or no epithelial thickening, thereby exhibiting reduced lung damage. Mouse serum and lung tissues were collected and analyzed to determine changes in endogenous metabolites using 1H-NMR. After target profiling, we identified metabolites showing the same tendency in the serum and lung as biomarkers for SHS-induced pulmonary damage, including taurine, glycerol, creatine, arginine, and leucine. As a result of histopathological examination, sulforaphane might inhibit SHS-induced lung damage, and metabolite analysis results suggest potential biomarkers for SHS-induced pulmonary damage in mice.

Microfluidic system with light intensity filters facilitating the application of photodynamic therapy for high-throughput drug screening.

BACKGROUND: Photodynamic therapy utilizes light energy with a photosensitizer (a light-sensitive drug) to kill cancer cells through creation of singlet oxygen via light activation. When a photosensitizer is injected into the bloodstream and exposed to a specific wavelength of light, it generates oxygen to destroy or damage nearby cancer cells, while minimizing side effects on normal cells. Although photodynamic therapy is effective for treating cancer, various parameters, such as the optimum light intensity and photosensitizer dose, are currently poorly understood due to the complexity of conventional experimental schemes. METHODS: To effectively perform a simultaneous single parallel test for several different light irradiation conditions on each cell, a microfluidic device was developed to generate eight different intensities from a single light-emitting diode source, through eight different color dye concentrations functioning as light intensity filters. To show that this novel high-throughput microfluidic system can analyze the effects of various light intensities during photodynamic therapy, the optimum light intensities and photosensitizer doses were determined for two different cancer cell lines. RESULTS: Optimum light intensities and photosensitizer were determined for all cell lines. The photodynamic therapy effects in response to different irradiated light intensities were characterized by analyzing cell viability after photosensitizer treatment CONCLUSIONS: : The developed platform is capable of being used as a photodynamic therapy screening tool. The proposed platform provides a simple and robust way to optimize the combined parameters of light intensity and dosage for diverse types of cancer cells.

Effects of tobacco compound 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) on the expression of epigenetically regulated genes in lung carcinogenesis.

Cigarette smoking is a major cause of lung cancer. Although tobacco smoking-induced genotoxicity has been well established, there is apparent lack of abundance functional epigenetic effects reported On cigarette smoke-induced lung carcinogenesis. The aim of this study was to determine effects of intratracheal administration of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) utilizing target gene expression DNA methylation patterns in lung tissues of mice following twice weekly for 8 weeks treatment. An unbiased approach where genomic regions was undertaken to assess early methylation changes within mouse pulmonary tissues. A methylated-CpG island recovery assay (MIRA) was performed to map the DNA methylome in lung tissues, with the position of methylated DNA determined using a Genome Analyzer (MIRA-SEQ). Alterations in epigenetic-regulated target genes were confirmed with quantitative reverse transcription-PCR, which revealed 35 differentially hypermethylated genes including Cdkn1C, Hsf4, Hnf1a, Cdx1, and Hoxa5 and 30 differentially hypomethylated genes including Ddx4, Piwi1, Mdm2, and Pce1 in NNK-exposed lung tissue compared with controls. The main pathway of these genes for mediating biological information was analyzed using the Kyoto Encyclopedia of Genes and Genomes database. Among them, Rssf1 and Mdm2 were closely associated with NNK-induced lung carcinogenesis. Taken together, our data provide valuable resources for detecting cigarette smoke-induced lung carcinogenesis.

Exposure to long-term evolution radiofrequency electromagnetic fields decreases neuroblastoma cell proliferation via Akt/mTOR-mediated cellular senescence.

The aim of this study was to examine the potential effects of long-term evolution (LTE) radiofrequency electromagnetic fields (RF-EMF) on cell proliferation using SH-SY5Y neuronal cells. The growth rate and proliferation of SH-SY5Y cells were significantly decreased upon exposure to 1760 MHz RF-EMF at 4 W/kg specific absorption rate (SAR) for 4 hr/day for 4 days. Cell cycle analysis indicated that the cell cycle was delayed in the G0/G1 phase after RF-EMF exposure. However, DNA damage or apoptosis was not involved in the reduced cellular proliferation following RF-EMF exposure because the expression levels of histone H2A.X at Ser139 (γH2AX) were not markedly altered and the apoptotic pathway was not activated. However, SH-SY5Y cells exposed to RF-EMF exhibited a significant elevation in Akt and mTOR phosphorylation levels. In addition, the total amount of p53 and phosphorylated-p53 was significantly increased. Data suggested that Akt/mTOR-mediated cellular senescence led to p53 activation via stimulation of the mTOR pathway in SH-SY5Y cells. The transcriptional activation of p53 led to a rise in expression of cyclin-dependent kinase (CDK) inhibitors p21 and p27. Further, subsequent inhibition of CDK2 and CDK4 produced a fall in phosphorylated retinoblastoma (pRb at Ser807/811), which decreased cell proliferation. Taken together, these data suggest that exposure to RF-EMF might induce Akt/mTOR-mediated cellular senescence, which may delay the cell cycle without triggering DNA damage in SH-SY5Y neuroblastoma cells.

Topical application of celastrol alleviates atopic dermatitis symptoms mediated through the regulation of thymic stromal lymphopoietin and group 2 innate lymphoid cells.

Atopic dermatitis is a chronic inflammatory skin disease, of which incidence is closely related to exposure to environmental pollutants and allergens. Thymic stromal lymphopoietin (TSLP) plays an important role in the early stages of atopic dermatitis development by inducing Th2 immune responses. In addition, TSLP regulates activation of group 2 innate lymphoid cells (ILC2), promoting the pathogenesis of atopic dermatitis. The aim of this study was to investigate whether celastrol alleviated atopic dermatitis symptoms by regulating TSLP expression and ILC2 stimulation. Celastrol suppressed TSLP production in mouse keratinocyte cells by inhibiting NF-ĸB activation. Topical application of celastrol significantly improved atopic dermatitis symptoms induced by house dust mite (HDM) in NC/Nga mice as determined by dermatitis score and histological assessment. Celastrol decreased the levels of TSLP in atopic dermatitis skin lesions of HDM-stimulated NC/Nga mice. Celastrol reduced levels of Th2 cytokines including IL-4, IL-5, and IL-13 in atopic dermatitis skin lesions of NC/Nga mice. Further, celastrol significantly reduced ILC2 population in atopic dermatitis skin lesions of NC/Nga mice. These results indicate that topical application of celastrol improved atopic dermatitis symptoms by lowering TSLP levels and concomitant immune responses. Data demonstrated that reduced TSLP levels and associated lower number of ILC2 cells alleviate atopic dermatitis symptoms induced by house dust mite.

Effects of anti-wrinkle and skin-whitening fermented black ginseng on human subjects and underlying mechanism of action.

The aim of this study was to determine the effects of anti-wrinkle and skin-whitening of fermented black ginseng (FBG) in human subjects and to examine underlying biochemical mechanisms of action. A clinical study was performed to evaluate efficacy and safety using a 1% FBG cream formulation. Twenty-three subjects were recruited and instructed to apply control or FBG creams each on half of their face twice daily for 8 weeks. After 8 weeks, FBG cream significantly reduced the appearance of eye wrinkles compared to prior to exposure and control cream. Skin color was significantly brightened using FBG cream in comparison with a control cream. To determine the mechanism of actions involved in anti-wrinkle and skin-whitening effects various concentrations of FBG were applied to human fibroblast CCD-986sk and mouse melanoma B16F1 cells. Collagen synthesis in CCD-986sk cells was improved significantly at 1, 3, 10, or 30 µg/ml of FBG. At 30 µg/ml, FBG significantly inhibited (73%) collagenase, and matrix metalloproteinase-1 (MMP-1) compared to control. Tyrosinase activity and DOPA (3,4-dihydroxy-L-phenylalanine) oxidation were significantly decreased at all tested concentrations. Melanin production in B16F1 cells was concentration-dependently reduced from 15% to 60% by all concentrations of FBG. These results suggested that a 1% FBG cream exerted anti-wrinkle and skin-whitening effects.

Effects of anti-wrinkle and skin-whitening fermented black ginseng on human subjects and underlying mechanism of action.

The aim of this study was to determine the effects of anti-wrinkle and skin-whitening of fermented black ginseng (FBG) in human subjects and to examine underlying biochemical mechanisms of action. A clinical study was performed to evaluate efficacy and safety using a 1% FBG cream formulation. Twenty-three subjects were recruited and instructed to apply control or FBG creams each on half of their face twice daily for 8 weeks. After 8 weeks FBG cream significantly reduced appearance of eye wrinkles compared to prior to exposure and control cream. Skin color was significantly brightened using FBG cream in comparison with control cream. To determine the mechanism of actions involved in anti-wrinkle and skin-whitening effects various concentrations of FBG were applied to human fibroblast CCD-986sk and mouse melanoma B16F1 cells. Collagen synthesis in CCD-986sk cells was improved significantly at 1, 3, 10, or 30 µg/ml of FBG. At 30 µg/ml, FBG significantly inhibited (73%) collagenase, and matrix metalloproteinase-1 (MMP-1) compared to control. Tyrosinase activity and DOPA (3,4-dihydroxy-L-phenylalanine) oxidation were significantly decreased at all tested concentrations. Melanin production in B16F1 cells was concentration-dependently reduced 15% to 60% by all concentrations of FBG. These results suggested that a 1% FBG cream exerted anti-wrinkle and skin-whitening effects.

Risk assessment of unintentional phthalates contaminants in cosmetics.

A risk assessment was performed for three types of phthalates, benzyl butyl phthalate (BBP), dibutyl phthalate (DBP), and di(2-ethylhexyl)phthalate (DEHP) unintentionally contaminated in cosmetics. A total of 100 products of 8 types of cosmetics were analyzed employing gas chromatography-mass spectrometry (GC-MS). By applying the maximum detected values of phthalates based on the worst exposure cases, their systemic exposure dosage (SED) was calculated. Accordingly, DEHP was identified as the main unintentional phthalates contaminants (0.10-600.00 ppm) in the cosmetics, with an SED of 3.37 × 10-9-3.75 × 10-4 mg/kg/day. In the non-cancer risk assessment, a margin of safety (MOS ≥ 100, safe) of 1.28 × 104-1.42 × 109 was estimated. In the cancer risk assessment, the lifetime cancer risk (LCR ≤ 10-5, safe) was determined to be 8.81 × 10-12-9.79 × 10-7. Based on the results of both risk assessments, the levels of unintentional phthalates contaminants in cosmetics were deemed safe. Some phthalates are widely used as plasticizers and are essential for daily life; however, various toxicities, including endocrine disruption, have been reported. Therefore, even under these "worst case" assumptions, an adequate margin of safety is shown such that this might be a low priority for further work although exposure to unintentional phthalates contaminants through cosmetics should be considered as part of cumulative exposure.

Integration of transcriptomics, proteomics and metabolomics identifies biomarkers for pulmonary injury by polyhexamethylene guanidine phosphate (PHMG-p), a humidifier disinfectant, in rats.

Polyhexamethylene guanidine phosphate (PHMG-p) was used as a humidifier disinfectant in Korea. PHMG induced severe pulmonary fibrosis in Koreans. The objective of this study was to elucidate mechanism of pulmonary toxicity caused by PHMG-p in rats using multi-omics analysis. Wistar rats were intratracheally instilled with PHMG-p by single (1.5 mg/kg) administration or 4-week (0.1 mg/kg, 2 times/week) repeated administration. Histopathologic examination was performed with hematoxylin and eosin staining. Alveolar macrophage aggregation and granulomatous inflammation were observed in rats treated with single dose of PHMG-p. Pulmonary fibrosis, chronic inflammation, bronchiol-alveolar fibrosis, and metaplasia of squamous cell were observed in repeated dose group. Next generation sequencing (NGS) was performed for transcriptome profiling after mRNA isolation from bronchiol-alveoli. Bronchiol-alveoli proteomic profiling was performed using an Orbitrap Q-exactive mass spectrometer. Serum and urinary metabolites were determined using 1H-NMR. Among 418 differentially expressed genes (DEGs) and 67 differentially expressed proteins (DEPs), changes of 16 mRNA levels were significantly correlated with changes of their protein levels in both single and repeated dose groups. Remarkable biological processes represented by both DEGs and DEPs were defense response, inflammatory response, response to stress, and immune response. Arginase 1 (Arg1) and lipocalin 2 (Lcn2) were identified to be major regulators for PHMG-p-induced pulmonary toxicity based on merged analysis using DEGs and DEPs. In metabolomics study, 52 metabolites (VIP > 0.5) were determined in serum and urine of single and repeated-dose groups. Glutamate and choline were selected as major metabolites. They were found to be major factors affecting inflammatory response in association with DEGs and DEPs. Arg1 and Lcn2 were suggested to be major gene and protein related to pulmonary damage by PHMG-p while serum or urinary glutamate and choline were endogenous metabolites related to pulmonary damage by PHMG-p.

Novel functions for 2-phenylbenzimidazole-5-sulphonic acid: Inhibition of ovarian cancer cell responses and tumour angiogenesis.

In this study, we investigated the effects and molecular mechanisms of 2-phenylbenzimidazole-5-sulphonic acid (PBSA), an ultraviolet B protecting agent used in sunscreen lotions and moisturizers, on ovarian cancer cell responses and tumour angiogenesis. PBSA treatment markedly blocked mitogen-induced invasion through down-regulation of matrix metalloproteinase (MMP) expression and activity in ovarian cancer SKOV-3 cells. In addition, PBSA inhibited mitogen-induced cell proliferation by suppression of cyclin-dependent kinases (Cdks), but not cyclins, leading to pRb hypophosphorylation and G1 phase cell cycle arrest. These anti-cancer activities of PBSA in ovarian cancer cell invasion and proliferation were mediated by the inhibition of mitogen-activated protein kinase kinase 3/6-p38 mitogen-activated protein kinase (MKK3/6-p38MAPK ) activity and subsequent down-regulation of MMP-2, MMP-9, Cdk4, Cdk2 and integrin ß1, as evidenced by treatment with p38MAPK inhibitor SB203580. Furthermore, PBSA suppressed the expression and secretion of vascular endothelial growth factor in SKOV-3 cells, leading to inhibition of capillary-like tubular structures in vitro and angiogenic sprouting ex vivo. Taken together, our results demonstrate the pharmacological effects and molecular targets of PBSA on modulating ovarian cancer cell responses and tumour angiogenesis, and suggest further evaluation and development of PBSA as a promising chemotherapeutic agent for the treatment of ovarian cancer.

Estrogen Deficiency Potentiates Thioacetamide-Induced Hepatic Fibrosis in Sprague-Dawley Rats.

Hepatic fibrosis is characterized by persistent deposition of extracellular matrix proteins and occurs in chronic liver diseases. The aim of the present study is to investigate whether estrogen deficiency (ED) potentiates hepatic fibrosis in a thioacetamide (TAA)-treated rat model. Fibrosis was induced via intraperitoneal injection (i.p.) of TAA (150 mg/kg/day) for four weeks in ovariectomized (OVX) female, sham-operated female, or male rats. In TAA-treated OVX rats, the activities of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and γ-glutamyl transferase (GGT) were significantly increased compared to those in TAA-treated sham-operated OVX rats or TAA-treated male rats. Furthermore, α-smooth muscle actin (α-SMA) expression was significantly increased compared to that in TAA-treated sham-operated rats. This was accompanied by the appearance of fibrosis biomarkers including vimentin, collagen-I, and hydroxyproline, in the liver of TAA-treated OVX rats. In addition, ED markedly reduced total glutathione (GSH) levels, as well as catalase (CAT) and superoxide dismutase (SOD) activity in TAA-treated OVX rats. In contrast, hepatic malondialdehyde (MDA) levels were elevated in TAA-treated OVX rats. Apoptosis significantly increased in TAA-treated OVX rats, as reflected by elevated p53, Bcl-2, and cleaved caspase 3 levels. Significant increases in interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) concentrations were exhibited in TAA-treated OVX rats, and this further aggravated fibrosis through the transforming growth factor-ß (TGF-ß)/Smad pathway. Our data suggest that ED potentiates TAA-induced oxidative damage in the liver, suggesting that ED may enhance the severity of hepatic fibrosis in menopausal women.

Risk assessment of volatile organic compounds (VOCs) detected in sanitary pads.

Disposable sanitary pads are a necessity for women's health, but safety concerns regarding the use of these products have created anxiety. The aim of this study was to conduct a risk assessment of 74 volatile organic compounds (VOCs), which were expected to be contained within sanitary pads. Of the 74 VOCs, 50 were found in sanitary pads retailed in Korea at concentrations ranging from 0.025 to 3548.09 µg/pad. In order to undertake a risk assessment of the VOCs, the toxicological database of these compounds in the United States Environmental Protection Agency (USEPA), Agency for Toxic Substances and Disease Registry (ATSDR), National Toxicology Program (NTP) and World Health Organization (WHO) was searched. Ethanol was found to exhibit the highest reference dose (RfD) while 1,2-dibromo-3-chloro-propane displayed the lowest RfD. Consequently, a worst-case exposure scenario was applied in this study. It was assumed that there was the use of 7.5 sanitary napkins/day for 7 days/month. In the case of panty liners or overnight sanitary napkins, the utilization of 90 panty liners/month or 21 overnight sanitary napkins/month was assumed, respectively. In addition, 43 kg, the body weight of 12 to 13-year-old young women, and 100% VOCs skin absorption were employed for risk assessment. The systemic exposure dose (SED) values were calculated ranging from 1.74 (1,1,2-trichloroethane) ng/kg/day to 144.4 (ethanol, absolute) µg/kg/day. Uncertainty factors (UFs) were applied ranging from 10 to 100,000 in accordance with the robustness of animal or human experiments. The margin of exposure (MOE) of 34 VOCs was more than 1 (acceptable MOE > 1). Applicable carcinogenic references reported that the cancer risk of five VOCs was below 10-6. Based on our findings, evidence indicates that the non-cancer and cancer risks associated with VOCs detected in sanitary pads currently used in South Korea do not pose an adverse health risk in women.

Alternative skin sensitization prediction and risk assessment using proinflammatory biomarkers, interleukin-1 beta (IL-1ß) and inducible nitric oxide synthase (iNOS).

As an alternative to animal tests for skin sensitization potency and risk assessment, cell viability and biomarkers related to skin sensitization were analyzed in THP-1 human monocytic leukemia cells. Cell viabilities of 90% (CV90) and 75% (CV75) were determined for 24 selected test chemicals. Further biomarkers related to skin sensitization were also determined under equivalent comparative conditions. In cell viability analyses, potent skin sensitizers exhibited high cytotoxicity, but non-sensitizers did not display this tendency. In biomarker analyses, interleukin-I beta (IL-1ß), inducible nitric oxide synthase (iNOS), IL-1ß+iNOS, and THP-1 IL-1ß+Raw 264.7 IL-1ß were found to be suitable for prediction of skin sensitization potency following classification as either skin sensitizers or non-sensitizers (accuracies of 91.7%, 87.5%, 83.3%, and 82.6%, respectively). A significant positive correlation was found between biomarkers and skin sensitization potency, with a correlation coefficient (R) of 0.7 or more (correlation coefficients of 0.77, 0.72, 0.7, and 0.84, respectively). Finally, the skin sensitization potency effective threefold concentration (EC) 3% was predicted using a biomarker equation, with resulting prediction rates (match rate with actual data) of 58.3%, 54.2%, 62.5%, and 60.9%, respectively. The prediction accuracy for the EC3 value obtained from animal data was calculated as 83.3%, 79.2%, 79.2%, and 73.9%, respectively. Thus, these biomarkers, IL-1ß and iNOS, may be alternatively used to predict skin sensitization potency and risk assessment.

Risk Assessment of Ethylhexyl Dimethyl PABA in Cosmetics.

Ethylhexyl dimethyl para-aminobenzoic acid (PABA) is an oily yellow liquid derivative of water-soluble PABA commonly used in sunscreen. Ethylhexyl dimethyl PABA is widely used as an ingredient in many cosmetics at an average concentration of 1.25% (0.5-2.0%) in Korea. Previous studies, including those involving animals, have demonstrated that ethylhexyl dimethyl PABA is toxic to the following four organs: testis, epididymis, spleen, and liver. In addition, experiments using human keratinocytes found that ethylhexyl dimethyl PABA inhibits cell growth and DNA synthesis at low concentrations, and halted the cell cycle of MM96L cells (human melanoma cell line) at the G1 phase. Despite limited clinical data in humans, many studies have confirmed increased mutagenicity of ethylhexyl dimethyl PABA following exposure to sunlight, which suggests that this molecule is likely to contribute to onset of sun-induced cancer despite protecting the skin through absorption of UVB. For risk assessment, the no observed adverse effect level (NOAEL) chosen was 100 mg/kg bw/day in a 4 weeks oral toxicity study. Systemic exposure dosage (SED) was 0.588 mg/kg bw/day for maximum use of ethylhexyl dimethyl PABA in cosmetics. Based on the risk assessment and exposure scenarios conducted in this study, the margin of safety (MOS) was calculated to be 180.18 for a sunscreen containing 8% ethylhexyl dimethyl PABA, which is the maximum level allowed by the relevant domestic authorities.

Risk Assessment of 5-Chloro-2-Methylisothiazol-3(2H)-One/2-Methylisothiazol-3(2H)-One (CMIT/MIT) Used as a Preservative in Cosmetics.

The mixture of 5-chloro-2-methylisothiazol-3(2H)-one (CMIT) and 2-methylisothiazol-3(2H)-one (MIT), CMIT/MIT, is a preservative in cosmetics. CMIT/MIT is a highly effective preservative; however, it is also a commonly known skin sensitizer. Therefore, in the present study, a risk assessment for safety management of CMIT/MIT was conducted on products containing 0.0015% of CMIT/MIT, which is the maximum MIT level allowed in current products. The no observed adverse effect level (NOAEL) for CMIT/MIT was 2.8 mg/kg bw/day obtained from a two-generation reproductive toxicity test, and the skin sensitization toxicity standard value for CMIT/MIT, or the no expected sensitization induction level (NESIL), was 1.25 µg/cm2/day in humans. According to a calculation of body exposure to cosmetics use, the systemic exposure dosage (SED) was calculated as 0.00423 mg/kg bw/day when leave-on and rinse-off products were considered. Additionally, the consumer exposure level (CEL) amounted to 0.77512 µg/cm2/day for all representative cosmetics and 0.00584 µg/cm2/day for rinse-off products only. As a result, the non-cancer margin of safety (MOS) was calculated as 633, and CMIT/MIT was determined to be safe when all representative cosmetics were evaluated. In addition, the skin sensitization acceptable exposure level (AEL)/CEL was calculated as 0.00538 for all representative cosmetics and 2.14225 for rinse-off products; thus, CMIT/MIT was considered a skin sensitizer when all representative cosmetics were evaluated. Current regulations indicate that CMIT/MIT can only be used at concentrations 0.0015% or less and is prohibited from use in other cosmetics products. According to the results of this risk assessment, the CMIT/MIT regulatory values currently used in cosmetics are evaluated as appropriate.

Risk Assessment of Triclosan, a Cosmetic Preservative.

Triclosan (TCS) is an antimicrobial compound used in consumer products. The purpose of current study was to examine toxicology and risk assessment of TCS based on available data. Acute toxicities of oral, transdermal and inhalation routes were low, and phototoxicity and neurotoxicity were not observed. Topical treatment of TCS to animal caused mild irritation. TCS did not induce reproductive and developmental toxicity in rodents. In addition, genotoxicity was not considered based on in vitro and in vivo tests of TCS. It is not classified as a carcinogen in international authorities such as International Agency for Research on Cancer (IARC). No-observed-adverse-effect level (NOAEL) was determined 12 mg/kg bw/day for TCS, based on haematoxicity and reduction of absolute and relative spleen weights in a 104-week oral toxicity study in rats. Percutaneous absorption rate was set as 14%, which was human skin absorption study reported by National Industrial Chemicals Notification and Assessment Scheme (NICNAS) (2009). The systemic exposure dosage (SED) of TCS has been derived by two scenarios depending on the cosmetics usage of Koreans. The first scenario is the combined use of representative cosmetics and oral care products. The second scenario is the combined use of rinse-off products of cleansing, deodorants, coloring products, and oral care products. SEDs have been calculated as 0.14337 mg/kg bw/day for the first scenario and 0.04733 mg/kg bw/day for the second scenario. As a result, margin of safety (MOS) for the first and second scenarios was estimated to 84 and 253.5, respectively. Based on these results, exposure of TCS contained in rinse-off products, deodorants, and coloring products would not pose a significant health risk when it is used up to 0.3%.

Risk Assessment of Drometrizole, a Cosmetic Ingredient used as an Ultraviolet Light Absorber.

As the use of cosmetics has greatly increased in a daily life, safety issues with cosmetic ingredients have drawn an attention. Drometrizole [2-(2'-hydroxy-5'-methylphenyl)benzotriazole] is categorized as a sunscreen ingredient and is used in cosmetics and non-cosmetics as a UV light absorber. No significant toxicity has been observed in acute oral, inhalation, or dermal toxicity studies. In a 13-week oral toxicity study in beagle dogs, No observed adverse effect level (NOAEL) was determined as 31.75 mg/kg bw/day in males and 34.6 mg/kg bw/day in females, based on increased serum alanine aminotransferase activity. Although drometrizole was negative for skin sensitization in two Magnusson-Kligman maximization tests in guinea pigs, there were two case reports of consumers presenting with allergic contact dermatitis. Drometrizole showed no teratogenicity in reproductive and developmental toxicity studies in which rats and mice were treated for 6 to 15 days of the gestation period. Ames tests showed that drometrizole was not mutagenic. A long-term carcinogenicity study using mice and rats showed no significant carcinogenic effect. A nail product containing 0.03% drometrizole was nonirritating, non-sensitizing and non-photosensitizing in a test with 147 human subjects. For risk assessment, the NOAEL chosen was 31.75 mg/kg bw/day in a 13-week oral toxicity study. Systemic exposure dosages were 0.27228 mg/kg bw/day and 1.90598 mg/kg bw/day for 1% and 7% drometrizole in cosmetics, respectively. Risk characterization studies demonstrated that when cosmetic products contain 1.0% of drometrizole, the margin of safety was greater than 100. Based on the risk assessment data, the MFDS revised the regulatory concentration of drometrizole from 7% to 1% in 2015. Under current regulation, drometrizole is considered to be safe for use in cosmetics. If new toxicological data are obtained in the future, the risk assessment should be carried out to update the appropriate guidelines.