Repeated-dose toxicity and toxicokinetic study of isobutylparaben in rats subcutaneously treated for 13 weeks

Parabens have historically served as antimicrobial preservatives in a range of consumables such as food, beverages, medications, and personal care products due to their broad-spectrum antibacterial and antifungal properties. Traditionally, these compounds were believed to exhibit low toxicity, causing minimal irritation, and possessing limited sensitization potential. However, recent evidence suggests that parabens might function as endocrine-disrupting chemicals (EDCs). Consequently, extensive research is underway to elucidate potential human health implications arising from exposure to these substances. Among these parabens, particular concerns have been raised regarding the potential adverse effects of iso-butylparaben (IBP). Studies have specifically highlighted its potential for inducing hormonal disruption, significant ocular damage, and allergic skin reactions. This study aimed to evaluate the prolonged systemic toxicity, semen quality, and estrus cycle in relation to endocrine disruption endpoints, alongside assessing the toxicokinetic behavior of IBP in Sprague-Dawley rats following a 13-week repeated subcutaneous administration. The rats were administered either the vehicle (4% Tween 80) or IBP at dosage levels of 2, 10, and 50 mg/kg/day for 13 weeks. Blood collection for toxicokinetic study was conducted on three specified days: day 1 (1st), day 30 (2nd), and day 91 (3rd). Systemic toxicity assessment and potential endocrine effects were based on various parameters including mortality rates, clinical signs, body weights, food and water consumption, ophthalmological findings, urinalysis, hematological and clinical biochemistry tests, organ weights, necropsy and histopathological findings, estrus cycle regularity, semen quality, and toxicokinetic behavior. The findings revealed that IBP induced local irritation at the injection site in males at doses ≥ 10 mg/kg/day and in females at 50 mg/kg/day; however, systemic toxicity was not observed. Consequently, the no-observed-adverse-effect level (NOAEL) for IBP was determined to be 50 mg/kg/day in rats of both sexes, indicating no impact on the endocrine system. The toxicokinetics of IBP exhibited dose-dependent systemic exposure, reaching a maximum dose of 50 mg/kg/day, and repeated administration over 13 weeks showed no signs of accumulation.

Biocidal products: Opportunities in risk assessment, management, and communication

In the coronavirus disease 2019 era, biocidal products are increasingly used for controlling harmful organisms, including microorganisms. However, assuring safety against adverse health effects is a critical issue from a public health standpoint. This study aimed to provide an overview of key aspects of risk assessment, management, and communication that ensure the safety of biocidal active ingredients and products. The inherent characteristics of biocidal products make them effective against pests and pathogens; however, they also possess potential toxicities. Therefore, public awareness regarding both the beneficial and potential adverse effects of biocidal products needs to be increased. Biocidal active ingredients and products are regulated under specific laws: the Federal Insecticide, Fungicide, and Rodenticide Act for the United States; the European Union (EU) Biocidal Products Regulation for the EU; and the Consumer Chemical Products and Biocide Safety Management Act for the Republic of Korea. Risk management also needs to consider the evidence of enhanced sensitivity to toxicities in individuals with chronic diseases, given the increased prevalence of these conditions in the population. This is particularly important for post-marketing safety assessments of biocidal products. Risk communication conveys information, including potential risks and risk-reduction measures, aimed at managing or controlling health or environmental risks. Taken together, the collaborative effort of stakeholders in risk assessment, management, and communication strategies is critical to ensuring the safety of biocidal products sold in the market as these strategies are constantly evolving.

Risk Assessment and Risk Reduction of Ptaquiloside in Bracken Fern

This study was conducted to determine the optimal boiling time to reduce ptaquiloside (PTA) and to carry out a risk assessment for PTA, a representative toxic substance found in bracken fern (BF; Pteridium aquilinum), which is frequently consumed as food in East Asian countries. High-performance liquid chromatography showed that the concentration of PTA in BF was reduced by up to 99% after boiling for 20 min. Risk assessment results showed that the cancer margin of exposure (MOE; ≥ 25,000 = safe) to PTA for an average daily exposure scenario after boiling BF for 20 min was considered safe. In addition, the non-cancer MOE (≥ 300 = safe) to PTA under an average daily exposure scenario after BF boiling for 20 min was considered safe. However, human exposure to PTA was considered unsafe under the non-boiled BF exposure and maximum daily exposure scenarios. Therefore, boiling BF for at least 20 min is recommended before consumption, to reduce exposure to PTA as much as possible.

Current trends in read-across applications for chemical risk assessments and chemical registrations in the Republic of Korea

Read-across, an alternative approach for hazard assessment, has been widely adopted when in vivo data are unavailable for chemicals of interest. Read-across is enabled via in silico tools such as quantitative structure activity relationship (QSAR) modeling. In this study, the current status of structure activity relationship (SAR)-based read-across applications in the Republic of Korea (ROK) was examined considering both chemical risk assessments and chemical registrations from different sectors, including regulatory agencies, industry, and academia. From the regulatory perspective, the Ministry of Environment (MOE) established the Act on Registration and Evaluation of Chemicals (AREC) in 2019 to enable registrants to submit alternative data such as information from read-across instead of in vivo data to support hazard assessment and determine chemical-specific risks. Further, the Ministry of Food and Drug Safety (MFDS) began to consider read-across approaches for establishing acceptable intake (AI) limits of impurities occurring during pharmaceutical manufacturing processes under the ICH M7 guideline. Although read-across has its advantages, this approach also has limitations including (1) lack of standardized criteria for regulatory acceptance, (2) inconsistencies in the robustness of scientific evidence, and (3) deficiencies in the objective reliability of read-across data. The application and acceptance rate of read-across may vary among regulatory agencies. Therefore, sufficient data need to be prepared to verify the hypothesis that structural similarities might lead to similarities in properties of substances (between source and target chemicals) prior to adopting a read-across approach. In some cases, additional tests may be required during the registration process to clarify long-term effects on human health or the environment for certain substances that are data deficient. To improve the quality of read-across data for regulatory acceptance, cooperative efforts from regulatory agencies, academia, and industry are needed to minimize limitations of read-across applications.

Read-across approaches: current applications and regulatory acceptance in Korea, Japan, and China

The aim of this paper was to investigate the current status of read-across approaches in the Republic of Korea, Japan, and China in terms of applications and regulatory acceptance. In the Republic of Korea, over the last 6 years, approximately 8% of safety data records used for chemical registrations were based upon read-across, and a guideline published on the use of read-across results in 2017. In Japan, read-across is generally accepted for screening hazard classification of toxicological endpoints according to the Chemical Substances Control Law (CSCL). In China, read-across data, along with data from other animal alternatives are accepted as a data source for chemical registrations, but could be only considered when testing is not technically feasible. At present, read-across is not widely used for chemical registrations and regulatory acceptance of read-across may differ among countries in Asia. With consideration of the advantages and limitations of read-across, it is expected that read-across may soon gradually be employed in Asian countries. Thus, regulatory agencies need to prepare for this progression.

Validation of Quantitative Structure-Activity Relationship (QSAR) and Quantitative Structure-Property Relationship (QSPR) approaches as alternatives to skin sensitization risk assessment

The aim of this study was conducted to validate the physicochemical properties of a total of 362 chemicals [305 skin sensitizers (212 in the previous study + 93 additional new chemicals), 57 non-skin sensitizers (38 in the previous study + 19 additional new chemicals)] for skin sensitization risk assessment using quantitative structure-activity relationship (QSAR)/quantitative structure-property relationship (QSPR) approaches. The average melting point (MP), surface tension (ST), and density (DS) of the 305 skin sensitizers and 57 non-sensitizers were used to determine the cutoff values distinguishing positive and negative sensitization, and correlation coefficients were employed to derive effective 3-fold concentration (EC3 (%)) values. QSAR models were also utilized to assess skin sensitization. The sensitivity, specificity, and accuracy were 80, 15, and 70%, respectively, for the Toxtree QSAR model; 88, 46, and 81%, respectively, for Vega; and 56, 61, and 56%, respectively, for Danish EPA QSAR. Surprisingly, the sensitivity, specificity, and accuracy were 60, 80, and 64%, respectively, when MP, ST, and DS (MP+ST+DS) were used in this study. Further, MP+ST+DS exhibited a sensitivity of 77%, specificity 57%, and accuracy 73% when the derived EC3 values were classified into local lymph node assay (LLNA) skin sensitizer and non-sensitizer categories. Thus, MP, ST, and DS may prove useful in predicting EC3 values as not only an alternative approach to animal testing but also for skin sensitization risk assessment.

Current opinion on risk assessment of cosmetics

Risk assessment of cosmetic ingredients is a useful scientific method to characterize potential adverse effects resulting from using cosmetics. The process of risk assessment consists of four steps: hazard identification, dose-response assessment, exposure assessment, and risk characterization. Hazard identification of chemicals refers to the initial stage of risk assessment and generally utilizes animal studies to evaluate toxicity. Since 2013, however, toxicity studies of cosmetic ingredients using animals have not been permitted in the EU and alternative toxicity test methods for animal studies have momentum to be developed for cosmetic ingredients. In this paper, we briefly review the alternative test methods that are available for cosmetic ingredients including read-across, in silico, in chemico, and invitro methods. In addition, new technologies such as omics and artificial intelligence (AI) have been discussed to expand or improve the knowledge and hazard identification of cosmetic ingredients. Aggregate exposure of cosmetic ingredients is another safety issue and methods for its improvement were reviewed. There have been concerns over the safety of nano-cosmetics for a long time, but the risk of nano-cosmetics remains unclear. Therefore, current issues of cosmetic risk assessment are discussed and expert opinion will be provided for the safety of cosmetics.

Thirteen-week subcutaneous repeated dose toxicity study of butylparaben and its toxicokinetics in rats

Parabens are widely used preservatives in cosmetics and pharmaceutical products and are approved as food additives. These chemicals have been considered safe for many years. However, the literature classifies parabens as endocrine-disrupting chemicals, and an assessment of their influence on the endocrine system and systemic toxicity is important. This study explored long-term systemic toxicity, effects on the endocrine system, and toxicokinetic behavior after repeated subcutaneous administration of butylparaben to Sprague-Dawley rats. Rats were treated with vehicle (4% Tween 80) or butylparaben at dose levels of 2, 10, and 50 mg/kg/day for 13 weeks. Assessment of systemic toxicity and endocrine-disrupting effects was based on mortality; clinical signs; body weight; food and water consumption; ophthalmological findings; urinalysis; hematology and clinical biochemistry; organ weights; necropsy and histopathological findings; regularity and length of the estrous cycle; semen quality; and toxicokinetic behavior. Female uterine weight and estrous cycle, and male semen quality indicated no estrogenic effects. Butylparaben induced local irritation at the injection site in both sexes at a dose of 50 mg/kg/day, but systemic toxicity was not observed. Therefore, the no-observed-adverse-effect level of butylparaben is set at 50 mg/kg/day in rats of both sexes. Butylparaben was without endocrine system effects at this dose. Butylparaben displays dose-dependent systemic exposure up to the maximum dose of 50 mg/kg/day and repeated administration of butylparaben for 13 weeks shows no bioaccumulation.

Risk communication for labeling all ingredients in consumer products

The labeling of all ingredients contained in consumer products has been requested by consumers concerned regarding their safety. Consequently, regulatory agencies have set guidelines for industries on how to provide safety information regarding the ingredients in their products. However, discordant opinions were raised from stakeholders, resulting in the formation of a risk communication forum among industries, regulatory agencies, consumer groups, and academia. There are several methods that might be utilized to provide ingredient information to consumers: (1) listing all ingredients on the label of products, (2) providing major ingredients on the label of products, (3) presenting all ingredients on the websites of each manufacturer, and (4) listing major ingredients on the label of products and the remainder of ingredients (not on the label) on the websites. Each method might have its own advantages and disadvantages with respect to providing the information regarding the names of the ingredients used in consumer products to the consumers. A continuous risk communication forum might be an effective tool to facilitate an improved understanding of chemical information, toxicological science, regulatory guidelines, labeling methods, and consumers' concern. This study suggests that risk communication efforts may be helpful and a good opportunity for stakeholders to exchange opinions and reach a harmonious conclusion on labeling of consumer products ingredients.

Detoxifying effects of optimal hyperoxia (40% oxygenation) exposure on benzo[a]pyrene-induced toxicity in human keratinocytes

Detoxifying effects of hyperoxia, which is widely used in clinical practice, were investigated using HaCat cells (human keratinocytes) treated with benzo[a]pyrene (B[a]P) as a model agent to induce adverse effects in the skin. It is well-established that B[a]P may produce toxicities including cancer, endocrine disruption, and phototoxicity involving DNA damage, free radical generation, and down regulation of nuclear factor erythroid 2-related factor 2 (Nrf2). It is well-known that Nrf2 is associated increase of antioxidant enzyme catalase (CAT) or detoxification enzyme glutathione S-transferase (GST) in HaCat cells treated with B[a]P under optimal condition of hyperoxia (40% oxygenation) conditions. To further examine the underlying basis of this phenomenon, factors affecting the expression of Nrf2 were determined. Nrf2 was upregulated accompanied by a rise in p38 MAPK, sequestosome-1 (also known as p62) and NF-κB. In contrast, Nrf2 was downregulated associated with an elevation in glycogen synthase kinase 3 beta (GSK-3β) and peroxisome proliferator-activated receptor alpha (PPARα). Hyperoxia was also found to diminish DNA damage and generation of free radicals initiated in B[a]P-treated cells which was attributed to an significant rise of Nrf2, leading to elevated antioxidant activities or detoxification proteins including heme oxygenase 1 (HO-1), superoxide dismutase (SOD), glutathione peroxidase-1/2 (GPX-1/2), CAT, GST and glutathione (GSH). In addition, factors related to skin aging were also altered by hyperoxia. Data suggest that optimal hyperoxia exposure of 40% oxygenation may reduce cellular toxicity induced by B[a]P in HaCat cells as evidenced by inhibition of DNA damage, free radical generation, and down-regulation of Nrf2.

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.

Quantitative structure-activity and quantitative structure-property relationship approaches as alternative skin sensitization risk assessment methods

This study aimed to predict skin sensitization potency of selected chemicals by quantitatively analyzing their physicochemical properties by employing quantitative structure-activity relationship (QSAR) and quantitative structure-property relationship (QSPR) approaches as alternative risk assessment methods to animal testing. Correlations between effective concentration for a stimulation index of 3 (EC3) (%), the amount of a chemical required to elicit a threefold increase in lymph node cell proliferative activity (stimulation index, ≥3), were calculated using local lymph node assay (LLNA) and physicochemical properties of 212 skin sensitizers and 38 non-sensitizers were investigated. The correlation coefficients between melting point (MP) and EC3 and between surface tension (ST) and EC3 were 0.65 and 0.69, respectively. The correlation coefficient for MP + ST and EC3 was estimated to be 0.72. Thus, correlation coefficients between EC3 and MP, ST, and MP + ST reliably predicted the skin sensitization potential of the chemicals with sensitivities of 72% (126/175), 70% (122/174), and 73% (116/158); specificities of 77% (27/35), 69% (22/32), and 81% (26/32); and accuracies of 73% (153/210), 70% (144/206), and 75% (142/190), respectively. Our findings suggest that the EC3 value may be more accurately predicted using the ST values of chemicals as opposed to MP values. Thus, information on MP and ST parameters of chemicals might be useful for predicting the EC3 values as not only an alternative approach to animal testing, but as a risk assessment method for skin sensitization.

Alternative skin sensitization prediction and risk assessment using proinflammatory biomarkers, interleukin-1 beta (IL-1β) 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-1β), inducible nitric oxide synthase (iNOS), IL-1β+iNOS, and THP-1 IL-1β+Raw 264.7 IL-1β 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-1β and iNOS, may be alternatively used to predict skin sensitization potency and risk assessment.

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.

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 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 phthalates in pharmaceuticals

Phthalates are used for industrial plasticizers to impart flexibility and durability to polyvinyl chloride. Despite widespread use of phthalates, reported endocrine-disrupting properties raise safety concerns for consumers. Since phthalates are permitted as excipients in controlled-release capsules and enteric coatings, patients taking drugs containing these chemicals may potentially be at some health risk. In this study, 102 distinct pharmaceutical products were analyzed by gas chromatography/mass spectrometry to determine phthalate content and maximal phthalate exposure rate was calculated. In 102 drug samples, di(2-ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP), and diethyl phthalate (DEP) were detected in 9.8, 27.45, and 5.88% of cases, respectively. The highest level of DEP was found in extended-release (ER) capsules with concentrations ranging from 935.5 to 1535.37 ppb. The highest levels of DBP (1.32-7.07 ppb) were detected in tablets, whereas highest level (7.07 ppb) of DEHP was found in suspension preparations. The phthalate hazard index (HI) (human exposure tolerable daily intake) was calculated for each sample, but no sample exhibited an HI value exceeding 1; the minimum value taken to indicate a serious health risk. Thus, no apparent serious health risk from phthalate exposure arises from taking these medications. The low HI values suggest that phthalate contamination in pharmaceuticals may not pose an apparent significant risk to humans. However, the sources of phthalate present in pharmaceutical products still needs to be investigated and verified through on-site inspections in manufacturing processes in order to minimize human exposure. It is recommended that measures be taken to prevent phthalate contamination in pharmaceuticals.

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%.

Perspectives on trace chemical safety and chemophobia: risk communication and risk management

Safety issues regarding consumer products contaminated with trace amounts of chemicals are of great concern to consumers, with the degree of concern occasionally escalating to the psychological syndrome, chemophobia (i.e., the fear of chemicals). Hazardous substances frequently implicated in safety concerns include heavy metals (arsenic, mercury, cadmium, and lead), volatile organic compounds (VOC) such as benzene and o-toluidine, pesticides, carcinogens, radioactive substances, and endocrine disrupting chemicals (EDC) such as bisphenol A and phthalates. To improve communication of risk to society, members of academia, government, consumer organizations, and industry participated in this workshop to discuss and exchange perspectives on trace chemical safety. From the perspective of academia, integrated risk assessments need to be implemented to encompass various exposure sources and routes. The identification and investigation of new exposure-related biomarkers are also recommended to verify direct causal relationships between specific chemical exposure and effects on human health. As for regulation, governments need to establish and maintain acceptable limits for trace chemicals in products. In addition, harmonized efforts need to be undertaken among government agencies to share regulatory limits and effectively control trace chemicals in consumer products. Manufacturers need to faithfully abide by Good Manufacturing Practice (GMP) guidelines, monitor sources of contamination, and minimize these for consumer safety. To effectively resolve safety issues arising from trace chemicals exposure, collaborative efforts are needed involving academia, government, consumer organizations, and industry. Further, scientific evidence-based risk assessment is a critical approach to effectively manage trace chemical safety issues.

Perspectives on trace chemical safety and chemophobia: risk communication and risk management

Safety issues regarding consumer products contaminated with trace amounts of chemicals are of great concern to consumers, with the degree of concern occasionally escalating to the psychological syndrome, chemophobia, i.e., the fear of chemicals. Hazardous substances frequently implicated in safety concerns include heavy metals (arsenic, mercury, cadmium, and lead), volatile organic compounds (VOC) such as benzene and o-toluidine, pesticides, carcinogens, radioactive substances, and endocrine disrupting chemicals (EDC) such as bisphenol A and phthalates. To improve communication of risk to society, members of academia, government, consumer organizations, and industry participated in this workshop to discuss and exchange perspectives on trace chemical safety. From the perspective of academia, integrated risk assessments need to be implemented to encompass various exposure sources and routes. The identification and investigation of new exposure-related biomarkers are also recommended to verify direct causal relationships between specific chemical exposure and effects on human health. As for regulation, governments need to establish and maintain acceptable limits for trace chemicals in products. In addition, harmonized efforts need to be undertaken among government agencies to share regulatory limits and effectively control trace chemicals in consumer products. Manufacturers need to faithfully abide by Good Manufacturing Practice (GMP) guidelines, monitor sources of contamination, and minimize these for consumer safety. To effectively resolve safety issues arising from trace chemicals exposure, collaborative efforts are needed involving academia, government, consumer organizations, and industry. Further, scientific evidence-based risk assessment is a critical approach to effectively manage trace chemical safety issues.

Percutaneous permeability of 1-phenoxy-2-propanol, a preservative in cosmetics

1-Phenoxy-2-propanol (PP) is used as a preservative in cosmetics. PP is currently permitted to be used to up to 1% in cosmetic formulations in Korea and Europe. For risk assessment, percutaneous absorption is a crucial factor, but dermal absorption of PP has not yet been reported. In this study, Franz diffusion method was used to determine the percutaneous penetration of PP using the dorsal skin of rats. Each formulation of shampoo or cream, 113.6 mg/cm², was applied to a donor compartment of Franz diffusion cell for 24 h. Receptor fluid was collected at 0, 1, 2, 4, 8, 12, and 24 h following dermal application. Remaining formulation was removed with a cotton swab after last sampling. Using tape stripping method, stratum corneum was removed. PP in epidermis and dermis was extracted in PBS for 24 h. The concentration of PP from the swab, stratum corneum, and epidermis and dermis samples was determined using high performance liquid chromatography. Total percutaneous absorption rates of PP for shampoo and cream were 50.0 ± 6.0% and 33.0 ± 3.2%, respectively. In vitro skin permeability was calculated as 1,377.2 ± 240.1 mg/cm² for shampoo and 1,038.0 ± 72.2 mg/cm² for cream for 24 h.

Risk assessment of endocrine disrupting phthalates and hormonal alterations in children and adolescents

Risk assessment and hormone evaluation were carried out for di(2-ethylhexyl) phthalate (DEHP) and dibutyl phthalate (DBP), endocrine disrupting chemicals (EDCs), in 302 Korean children (n = 223) and adolescents (n = 79) (< age 19). Urinary and serum concentrations of DEHP, MEHP (mono(2-ethylhexyl) phthalate), DBP, MBP (monobutyl phthalate), and PA (phthalic acid, a common final metabolite of phthalates) were detected in children and adolescents. Daily exposure levels were estimated to be 16.45 ± 36.50 μg/kg b.w./day for DEHP, which is one-third of the tolerable daily intake (TDI) value (50 μg/kg b.w./day), but 14 out of 302 participants had a hazard index (HI = intake/TDI) value >1. The mean daily exposure level of DBP was 1.23 ± 1.45 μg/kg b.w./day, which is one-eighth of the TDI value (10 μg/kg b.w./day), but 1 out of 302 participants had a HI value > 1. Positive correlations were observed between serum DBP or MEHP, and serum estradiol (E2) and/or luteinizing hormone (LH) in prepubescent children. In addition, serum MBP levels were found to be negatively correlated with serum triiodothyronine (T3) or thyroxine (T4) in male participants, and serum DEHP levels with serum thyroid stimulating hormone (TSH) in female adolescents. Low-density lipoprotein (LDL) levels were positively correlated with serum PA levels in children and adolescents. DEHP, DBP or its metabolites may be associated with altered hormone levels in children and adolescents. Data suggest that exposure levels of DEHP and DBP in Korean children need to be reduced to levels below TDI to protect them from EDC-mediated toxicities. Abbreviations: DBP: dibutyl phthalate; DEHP: di(2-ethylhexyl) phthalate; E2: estradiol; EDC: endocrine disrupting chemical; EFSA: European Food Safety Authority; FSH: follicle stimulating hormone; HDL: high density lipoprotein; HI: hazard index; LDL: low density lipoprotein; LH: luteinizing hormone; MEHP: mono(2-ethylhexyl) phthalate; MBP: monobutyl phthalate; PA: phthalic acid; PPAR: peroxisome proliferator-activated receptor gamma; PVC: polyvinyl chloride; T3: triiodothyronine; T4: thyroxine; TDI: tolerable daily intake; TG: triglyceride; TSH: thyroid stimulating hormone; UPLC/MS/MS: Ultra Performance Liquid Chromatography/Tandem Mass Spectrometry; WWF: World Wildlife Fund.

Determination of fragrance allergens and their dermal sensitization quantitative risk assessment (QRA) in 107 spray perfumes

Cutaneous allergy occurs primarily as a result of using cosmetic, household, and laundry products available on the market that contain fragrances. The aim of this study was to develop a rapid and specific high-performance liquid chromatography with ultraviolet detection (HPLC-UV) method for quantification of 25 fragrance allergens (amyl cinnamyl alcohol, benzyl alcohol, benzyl benzoate, benzyl cinnamate, benzyl salicylate, citronellol, cinnamyl alcohol, citral, coumarin, eugenol, farnesol, geraniol, hydroxycitronellal, HICC (4-(4-hydroxy-4-methylpentyl)-3-cyclohexene-1-carboaldehyde), isoeugenol, isoeugenyl acetate, lilial (butyl phenyl methyl propional), limonene, linalool, methyl 2-octynoate, etc.). In addition, an exposure-based quantitative risk assessment (QRA) was performed to determine safe levels of fragrance ingredients in 107 perfumes. In 76 women's and 31 men's fragrances, 25 allergens were identified at concentrations ranging from undetectable (N.D.) to 8,997.68 mg/kg, and from N.D. to 17,352.34 mg/kg, respectively. An exposure-based sensitization QRA revealed that the ratios of acceptable exposure level (AEL) to consumer exposure level (CEL) of fragrance ingredients were greater than 1, suggesting an absence of skin sensitizing potential. However, the maximum level used in the exposure scenario was determined by the product purpose and application type, and AEL/CEL ratios of lilial, HICC, citral, isoeugenol, and methyl 2-octynoate analyzed in women's perfume were 0.53, 0.67 0.19, 0.13, and 0.57, respectively. As the ratios of AEL:CEL of these fragrance ingredients were below 1, the utilization of these potential skin sensitizers is not considered safe. Our findings indicate that the sensitization risk of allergens with AEL:CEL ratios below 1 detected in fragrances needs to be reduced to the appropriate human safety level for risk management.

P-gp Inhibition by the Anti-psychotic Drug Pimozide Increases Apoptosis, as well as Expression of pRb and pH2AX in Highly Drug-resistant KBV20C Cells

BACKGROUND/AIM

The present study was designed to identify drugs that could sensitize P-glycoprotein (P-gp)-overexpressing resistant KBV20C cancer cells to treatment with Halaven (HAL) or vincristine (VIC).

MATERIALS AND METHODS

Using relatively low doses or IC₅₀ concentrations of drugs to sensitize anti-mitotic drug-resistant KBV20C cells, pimozide (PIM) sensitized HAL-resistant KBV20C cancer cells, with higher P-gp inhibitory activity than another anti-psychotic drug, fluphenazine (FLU).

RESULTS

The first-generation P-gp inhibitor verapamil required a dose that was similar to that of PIM for P-gp inhibition, suggesting that PIM has a similar specificity for binding P-gp to prevent efflux of anti-mitotic drugs. Furthermore, co-treatment with PIM and another anti-mitotic drug, VIC, also increased sensitization of KBV20C cells, suggesting that PIM can be combined with other anti-mitotic drugs to sensitize resistant cancer cells. PIM caused a reduction in cell viability and an increase in the number of cells arresting at the G₂ phase of the cell cycle. PIM induced both early and late apoptosis in KBV20C cells in response to HAL treatment. Furthermore, the DNA damage marker pH2AX, the cell-cycle protein pRb, and the pro-apoptotic protein C-PARP levels increased after HAL-PIM co-treatment, indicative of a mechanism involving G₂ phase arrest and an increase in the number of cells undergoing apoptosis.

CONCLUSION

PIM may be a promising therapeutic agent for the treatment of cancers that are resistant to anti-mitotic drugs.

Phloxine O, a Cosmetic Colorant, Suppresses the Expression of Thymic Stromal Lymphopoietin and Acute Dermatitis Symptoms in Mice

Cosmetics are primarily applied to the skin; therefore, the association of cosmetic dyes with skin diseases or inflammation is a topic of great interest. Thymic stromal lymphopoietin (TSLP) is an interleukin 7-like cytokine that activates dendritic cells to promote Th2 inflammatory immune responses. TSLP is highly expressed in keratinocytes under inflammatory conditions, which suggests that it may play a critical role in the development of skin diseases, such as atopic dermatitis. Therefore, we investigated whether cosmetic dyes influenced the production of TSLP by keratinocytes. Phloxine O, also known as D&C Red No.27, is one of the most common red synthetic pigments and is widely used in colored cosmetics. Our results showed that Phloxine O downregulated phorbol 12-myristate 13-acetate-induced production of TSLP in a murine keratinocyte cell line (PAM212). Phloxine O also suppressed TSLP expression in KCMH-1 cells, which are mouse keratinocytes that constitutively produce high levels of TSLP. To investigate the in vivo effects of Phloxine O, we induced TSLP expression in mouse ear skin by topically applying MC903, a vitamin D3 analogue that is a well-known inducer of atopic dermatitis-like symptoms. Topical application of Phloxine O prevented MC903-induced TSLP production in mouse ear skin, attenuated the acute dermatitis-like symptoms and decreased serum IgE and histamine levels in mice. Suppression of TSLP expression by Phloxine O correlated with reduced expression of OX40 ligand and Th2 cytokines in mouse ear skin. Our results showed that Phloxine O may be beneficial to prevent dermatitis by suppressing the expression of TSLP and Th2 cytokines in skin.

IL-1α and IL-1β as alternative biomarkers for risk assessment and the prediction of skin sensitization potency

Potential biomarkers of skin sensitization in RAW264.7 mouse macrophages were investigated as alternatives to animal experiments and risk assessment. The concentrations that resulted in a cell viability of 90% (CV90) and 75% (CV75) were calculated by using a water-soluble tetrazolium salt (WST)-1 assay and used to analyze the skin sensitization potency of 23 experimental materials under equivalent treatment conditions. In addition, the expression of interleukin (IL)-1α, IL-1β, IL-31, tumor necrosis factor (TNF)-α, inducible nitric oxide synthase (iNOS), prostaglandin E2 (PGE2), and cyclooxygenase-2 (COX-2) was analyzed utilizing Western blotting. In the cell viability analysis, skin sensitizers were generally more cytotoxic and exhibited increased skin sensitization potency. However, nonsensitizers did not show any marked cytotoxic tendency. Biomarker analysis demonstrated that IL-1α, IL-1β, and the combination of IL-1α and IL-1β (IL-1α + IL-1β) predicted reliably skin sensitization potential (1) sensitivities of 94.4%, 83.3%, and 83.3%, specificities of 100%, 100%, and 100%, and (2) accuracies of 95.7%, 87%, and 87%, respectively. These observations correlated most reliably as indicators for skin sensitization potency. Data suggest that IL-1α and IL-1β may serve as potential biomarkers for skin sensitization and provide an alternative method to animal experiments for prediction of skin sensitization potency and risk assessment.

Inhibition of di(2-ethylhexyl) phthalate (DEHP)-induced endocrine disruption by co-treatment of vitamins C and E and their mechanism of action

The endocrine disrupting actions of di(2-ethylhexyl) phthalate (DEHP) on testicular functions are postulated to involve excess free radical generation. Thus the aim of this study was to examine the ability of antioxidant vitamins C and E to prevent DEHP-induced testicular disruption in male Sprague-Dawley (SD) rats. SD male rats were administered DEHP alone or DEHP with vitamin C and/or vitamin E for 30 days. DEHP alone increased the levels of testosterone (T) and reduced estradiol (E₂) concentrations. Supplementation with antioxidant vitamins diminished or restored serum T levels noted in DEHP-treated rats to control values. In contrast vitamins C and E increased E₂ levels to control in rats administered DEHP. Antioxidants significantly improved the decreased testicular levels of reduced glutathione and activity of superoxide dismutase compared to DEHP-treatment alone. Co-treatment of vitamins C and E also markedly improved the reduced epididymal sperm head counts and elevated levels of malondialdehyde (MDA) or 8-hydroxydeoxyguanosine (8-OHdG) induced by DEHP treatment. These results support the concept that the adverse actions of DEHP may be related to increased free radical generation while co-treatment with vitamins C and E significantly blocked the actions of DEHP on male testicular functions.

The general Assembly of the International Association of Environmental Mutagenesis and Genomics Societies (IAEMGS) in 2017

The International Association of Environmental Mutagenesis and Genomics Societies (IAEMGS) is a global organization that promotes applied and basic research on environmental mutagenesis and genomics. IAEMGS is composed of 13 national and regional societies of environmental mutagenesis and genomics and the total membership is approximately 4000. IAEMGS convenes the general assembly every four years during each International Conference on Environmental Mutagens (ICEM) for communication among members of participating societies and discussion on future directions. The latest general assembly was held during the 12^th ICEM/5^th Asian Conference on Environmental Mutagens (ACEM) in November 2017 in Incheon, Korea. This report summarizes the topics and discussions in the general assembly.

Risk assessment of N-nitrosodiethylamine (NDEA) and N-nitrosodiethanolamine (NDELA) in cosmetics

N-nitrosamines and their precursors found in cosmetics may be carcinogenic in humans. Thus the aim of this study was to carry out risk assessment for N-nitrosamines (N-nitrosodiethanolamine [NDELA], N-nitrosodiethylamine [NDEA]) and amines (triethanolamine [TEA], diethanolamine [DEA]) levels in cosmetics determined using validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) procedures. NDELA and NDEA concentrations were present at levels of "not detected" (N.D.) to 596.5 μg/kg and N.D. to 40.9 μg/kg, respectively. TEA and DEA concentrations ranged from N.D. to 860 μg/kg and N.D. to 26.22 μg/kg, respectively. The nitrite concentration (3-2250 mg/l), number of nitrosating agents to a maximum 5, and pH (3.93-10.09) were also assessed. The impact of N-nitrosamine formation on the levels of TEA, DEA, nitrite, and other nitrosating agents was also examined. N-nitrosamine concentrations correlated with the number of nitrosating agents and nitrite concentrations. Data demonstrated that higher nitrite concentrations and a greater number of nitrosating agents increased NDELA and NDEA yields. Further, the presence of TEA and DEA exerted a significant influence on N-nitrosamine formation. Risk assessments, including the margin of exposure (MOE) and lifetime cancer risk (LCR) for N-nitrosamines and margin of safety (MOS) for amines, were calculated using product type, use pattern, and concentrations. Exposure to maximum amounts of NDELA and NDEA resulted in MOE > 10,000 (based upon the benchmark dose lower confidence limit 10%) and LCR <1 × 10^-5, respectively. In addition, TEA and DEA concentrations in cosmetic samples resulted in MOS values >100. Therefore, no apparent safety concerns were associated with cosmetic products containing NDELA, NDEA, TEA, and DEA in this study. However, since amines and nitrosating agents produce carcinogenic nitrosamines, their use in cosmetics needs to be minimized to levels as low as technically feasible.

Non-cancer, cancer, and dermal sensitization risk assessment of heavy metals in cosmetics

The heavy metal content of cosmetics may be a cause for concern in that exposure to these metals is associated with adverse consequences. Thus, the aim of this study was to assess consequences attributed to exposure to heavy metals in cosmetics as determined by non-cancer, cancer, and sensitization risks methodologies. The quantification and exposure assessments of aluminum (Al), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), lead (Pb), mercury (Hg), cadmium (Cd), antimony (Sb), and titanium (Ti) were performed by inductively coupled plasma-mass spectrometry. The non-cancer risk assessment of Al, Cr³⁺, Mn, Fe, Co, Ni, Cu, Zn, Cd, Sb, and Ti in cosmetic samples resulted in a margin of safety (MOS) greater than 100 or a hazard index (HI) of less than 1. However, the probability of lifetime cancer risk (LCR) resulting from dermal exposure to heavy metals from cosmetics exceeded the acceptable risk levels (LCR > 10^-5). An exposure-based sensitization quantitative risk assessment determined that the ratios of acceptable exposure level to consumers for Ni, Co, Cu, or Hg were above 1, suggesting an absence of skin-sensitizing potential. For an average daily user of lip cosmetics, the estimated intakes of heavy metals were within the acceptable daily intake (ADI). The percentage of heavy users for which metal intakes exceeded ADIs were 20.37% for Pb, 9.26% for Mn, 1.85% for Cr³⁺, and 1.85% for Cr⁶⁺, respectively. Data suggested that the heavy metals present in cosmetics do not appear to pose a serious risk to health. However, for heavy users of lip cosmetics, contamination with some heavy metals, such as Pb, Mn, and Cr needs to be minimized.

Formation and inhibition of N-nitrosodiethanolamine in cosmetics under pH, temperature, and fluorescent, ultraviolet, and visual light

N-nitrosodiethanolamine (NDELA), a type of nitrosamine, is a possible human carcinogen that may form in cosmetic products. The aim of this study was to examine the formation and inhibition of NDELA through chemical reactions of secondary amines including mono-ethanolamine, di-ethanolamine (DEA), and tri-ethanolamine (TEA), and sodium nitrite (SN) under varying conditions such as pH, temperature, and fluorescent, ultraviolet (UV), and visual light (VIS) using liquid chromatography-mass spectroscopy. In a mixture of TEA and SN under acidic conditions pH 2, residual NDELA concentrations rose significantly under various storage conditions in the following order: 50°C > 40°C > UV (2 W/m²) > VIS (4000 lux) > fluorescent light > 25°C > 10°C. In a mixture of DEA and SN under the same acidic pH 2 conditions, NDELA formation was significantly elevated in the following order: UV (2 W/m²) > VIS (4000 lux) > 50°C > 40°C > fluorescent light > 25°C > 10°C. Inhibition of NDELA formation by d-mannitol, vitamin C (Vit C), or vitamin E (Vit E) was determined under varying conditions of pH, temperature, and fluorescent, UV, and VIS. At high concentrations of 100 or 1000 µg/ml, Vit E significantly decreased residual NDELA compared with control levels under acidic pH 2, but not under basic pH 6. Among various antioxidants, Vit E reacted more effectively with many nitrosating agents such as nitrate and nitrite found in cosmetic products. Therefore, to reduce NDELA, it is recommended that cosmetics be stored under cool/amber conditions and that Vit E or Vit C inhibitors of nitrosation be optimally added to cosmetic formulations at concentrations between 100 and 1000 µg/ml.

Risk management of free radicals involved in air travel syndromes by antioxidants

Frequent air travelers and airplane pilots may develop various types of illnesses. The environmental risk factors associated with air travel syndromes (ATS) or air travel-related adverse health outcomes raised concerns and need to be assessed in the context of risk management and public health. Accordingly, the aim of the present review was to determine ATS, risk factors, and mechanisms underlying ATS using scientific data and information obtained from Medline, Toxline, and regulatory agencies. Additional information was also extracted from websites of organizations, such as the International Air Transport Association (IATA), International Association for Medical Assistance to Travelers (IAMAT), and International Civil Aviation Organization (ICAO). Air travelers are known to be exposed to environmental risk factors, including circadian rhythm disruption, poor cabin air quality, mental stress, high altitude conditions, hormonal dysregulation, physical inactivity, fatigue, biological infections, and alcoholic beverage consumption. Consequences of ATS attributed to air travel include sleep disturbances (e.g., insomnia), mental/physical stress, gastrointestinal disorders, respiratory diseases, circulatory-related dysfunction, such as cardiac arrest and thrombosis and, at worst, mechanical and terrorism-related airplane crashes. Thus safety measures in the cabin before or after takeoff are undertaken to prevent illnesses or accidents related to flight. In addition, airport quarantine systems are strongly recommended to prepare for any ultimate adverse circumstances. Routine monitoring of environmental risk factors also needs to be considered. Frequently, the mechanisms underlying these adverse manifestations involve free radical generation. Therefore, antioxidant supplementation may help to reduce or prevent adverse outcomes by mitigating health risk factors associated with free radical generation.

P-gp Inhibition by XL019, a JAK2 Inhibitor, Increases Apoptosis of Vincristine-treated Resistant KBV20C Cells with Increased p21 and pH2AX Expression

The present study was designed to identify conditions that could increase the sensitivity of resistant cancer cells to antimitotic drugs. We investigated whether a Janus kinase 2 (JAK2) inhibitor used in clinical trials, XL019, sensitizes antimitotic drug-resistant KBV20C cells. XL019 reduced cellular viability and increased apoptosis in vincristine-treated KBV20C cells, independently of the JAK/signal transducer and activator of transcription (STAT) pathway. Based on the ATP-binding cassette protein B1 [ABCB1, P-glycoprotein (P-gp)] inhibitory assay, we demonstrated that XL019 functions as a P-gp inhibitor in drug-resistant KBV20C cells. Considering that another JAK2 inhibitor, CEP-33779, also inhibited P-gp and sensitized drug-resistant cancer cells in a previous study, we concluded that JAK2 inhibitors can be used as P-gp inhibitors in drug-resistant cancer cells. Fluorescence-activated cell sorting, western blot, and annexin V analyses were used to further investigate the mechanism of action of XL019 in vincristine-treated KBV20C cells. XL019 induced early apoptosis of KBV20C cells in response to vincristine treatment via increased G₂ phase arrest. Moreover, G₂ phase arrest and apoptosis of cells co-treated with vincristine and XL019 resulted from the up-regulation of phosphorylated retinoblastoma protein (pRb), p21, and the DNA-damage protein, phosphorylated H2A histone family, member X (pH2AX). Additionally, the P-gp-inhibitory effect of XL019 was less than that of CEP-33779, and a more than 2-fold higher dose was required to sensitize vincristine-treated KBV20C cells. Furthermore, lower doses of XL019 were required to sensitize KBV20C cells to a degree similar to that obtained with the established P-gp inhibitor verapamil, suggesting that XL019 has higher specificity than verapamil. Our results showed that JAK2 inhibitors inhibited P-gp action via a direct binding mechanism, which was similar to that of verapamil. These findings indicate that JAK2 inhibitors may be promising therapeutics for the treatment of cancer that is resistant to antimitotic drugs.

Risk assessment of benzalkonium chloride in cosmetic products

A risk assessment of benzalkonium chloride (BAC) was conducted based upon its toxicological profile and exposure evaluation. Since 1935, BAC has been used in a wide variety of products such as disinfectants, preservatives, and sanitizers. It is well-established that BAC is not genotoxic nor does it display tumorigenic potential, but safety concerns have been raised in local usage such as for ocular and intranasal applications. The Foundation of Korea Cosmetic Industry Institute (KCII) reported that in a hair conditioner manufactured as a cosmetic or personal product in South Korea, BAC was present at concentrations of 0.5-2%. The systemic exposure dosage (SED) was determined using the above in-use concentrations and a risk assessment analysis was conducted. The Margin of Safety (MOS) values for hair conditioners were calculated to be between 621 and 2,483. The risk of certain personal and cosmetic products was also assessed based upon assumptions that BAC was present at the maximal level of regulation in South Korea and that the maximal amount was used. The MOS values for the body lotion were all above 100, regardless of the application site. Collectively, data indicate that there are no safety concerns regarding use of products that contain BAC under the current concentration restrictions, even when utilized at maximal permitted levels. However, a chronic dermal toxicity study on BAC and comprehensive dermal absorption evaluation needs to be conducted to provide a more accurate prediction of the potential health risks to humans.

Highly Eribulin-resistant KBV20C Oral Cancer Cells Can Be Sensitized by Co-treatment with the Third-generation P-Glycoprotein Inhibitor, Elacridar, at a Low Dose

BACKGROUND/AIM

Eribulin mesylate, also called Halaven® (HAL), was recently developed as a microtubule-targeting drug and is used in the clinic for resistant or metastatic cancer. Previously, we showed that P-glycoprotein (P-gp)-overexpressing KBV20C oral cancer cells are highly resistant to HAL compared to sensitive KB cells. This qualitative study was designed to identify specific P-gp inhibitors that increase the sensitivity of highly resistant cancer cells to HAL.

MATERIALS AND METHODS

In order to identify functional P-gp inhibitors, HAL-treated KBV20C cells were co-treated with P-gp inhibitors, verapamil, elacridar, cyclosporine A, mitotane, piperine, fumagillin, curcumin, indomethacin, probenecid, sulindac, tesmilifene, and C-4. We then evaluated which P-gp inhibitors required a low dose to sensitize KBV20C cells to HAL. We also determined whether a low dose of a P-gp inhibitor could inhibit P-gp efflux pumping.

RESULTS

We found that cyclosporine A sensitized HAL-treated KBV20C cells at a low dose, whereas verapamil, another first-generation P-gp inhibitor, required a dose that was nearly 10-fold higher. We also found that the natural products, piperine and mitotane, sensitized KBV20C cells to HAL co-treatment. Interestingly, we found that elacridar, a third-generation P-gp inhibitor, sensitized HAL-treated cells at a low dose. Elacridar required approximately a 500-fold lower dose than that of verapamil to exert a similar effect. All inhibitors showed P-gp inhibitory activity that correlated with sensitivity to HAL.

CONCLUSION

These results suggest that highly HAL-resistant cancer cells can be sensitized with cyclosporine A or elacridar, specific P-gp inhibitors that exert their effects at a low dose. These findings provide important information regarding the sensitization of highly HAL-resistant cells with selective P-gp inhibitors and indicate that elacridar may be used to treat such highly HAL-resistant cancer cells.

Risk assessment of zinc oxide, a cosmetic ingredient used as a UV filter of sunscreens

Zinc oxide (ZnO), an inorganic compound that appears as a white powder, is used frequently as an ingredient in sunscreens. The aim of this review was to examine the toxicology and risk assessment of ZnO based upon available published data. Recent studies on acute, sub-acute, and chronic toxicities of ZnO indicated that this compound is virtually non-toxic in animal models. However, it was reported that ZnO nanoparticles (NP) (particle size, 40 nm) induced significant changes in anemia-related hematologic parameters and mild to moderate pancreatitis in male and female Sprague-Dawley rats at 536.8 mg/kg/day in a 13-week oral toxicity study. ZnO displayed no carcinogenic potential, and skin penetration is low. No-observed-adverse-effect level (NOAEL) ZnO was determined to be 268.4 mg/kg/day in a 13-week oral toxicity study, and a maximum systemic exposure dose (SED) of ZnO was estimated to be 0.6 mg/kg/day based on topical application of sunscreen containing ZnO. Subsequently, the lowest margin of safety (MOS) was estimated to be 448.2, which indicates that the use of ZnO in sunscreen is safe. A risk assessment was undertaken considering other routes of exposure (inhalation or oral) and major product types (cream, lotion, spray, and propellant). Human data revealed that MOS values (7.37 for skin exposure from cream and lotion type; 8.64 for skin exposure of spray type; 12.87 for inhalation exposure of propellant type; 3.32 for oral exposure of sunscreen) are all within the safe range (MOS > 1). Risk assessment of ZnO indicates that this compound may be used safely in cosmetic products within the current regulatory limits of 25% in Korea.

Extracellular ATP Induces Calcium Signaling in Odontoblasts

Odontoblasts form dentin at the outermost surface of tooth pulp. An increasing level of evidence in recent years, along with their locational advantage, implicates odontoblasts as a secondary role as sensory or immune cells. Extracellular adenosine triphosphate (ATP) is a well-characterized signaling molecule in the neuronal and immune systems, and its potential involvement in interodontoblast communications was recently demonstrated. In an effort to elaborate the ATP-mediated signaling pathway in odontoblasts, the current study performed single-cell reverse transcription polymerase chain reaction (RT-PCR) and immunofluorescent detection to investigate the expression of ATP receptors related to calcium signal in odontoblasts from incisal teeth of 8- to 10-wk-old rats, and demonstrated an in vitro response to ATP application via calcium imaging experiments. While whole tissue RT-PCR analysis detected P2Y₂, P2Y₄, and all 7 subtypes (P2X₁ to P2X₇) in tooth pulp, single-cell RT-PCR analysis of acutely isolated rat odontoblasts revealed P2Y₂, P2Y₄, P2X₂, P2X₄, P2X₆, and P2X₇ expression in only a subset (23% to 47%) of cells tested, with no evidence for P2X₁, P2X₃, and P2X₅ expression. An increase of intracellular Ca²⁺ concentration in response to 100μM ATP, which was repeated after pretreatment of thapsigargin or under the Ca²⁺-free condition, suggested function of both ionotropic and metabotropic ATP receptors in odontoblasts. The enhancement of ATP-induced calcium response by ivermectin and inhibition by 5-(3-bromophenyl)-1,3-dihydro-2H-benzofuro[3,2-e]-1,4-diazepin-2-one (5-BDBD) confirmed a functional P2X₄ subtype in odontoblasts. Positive calcium response to 2',3'-O-(benzoyl-4-benzoyl)-ATP (BzATP) and negative response to α,β-methylene ATP suggested P2X₂, P2X₄, and P2X₇ as functional subunits in rat odontoblasts. Single-cell RT-PCR analysis of the cells with confirmed calcium response and immunofluorescent detection further corroborated the expression of P2X₄ and P2X₇ in odontoblasts. Overall, this study demonstrated heterogeneous expression of calcium-related ATP receptor subtypes in subsets of individual odontoblasts, suggesting extracellular ATP as a potential signal mediator for odontoblastic functions.

Impact of anesthesia on cancer recurrence

Surgery remains the mainstay treatment in the majority of solid cancers. Anesthetics and analgesics used during the perioperative period may modulate the innate and adaptive immune system, inflammation and angiogenesis, and have a direct effect on cancer cells that could ultimately modify oncological outcomes. For instance, volatile anesthetics and opioid analgesics have shown predominantly pro-tumor effects, while propofol, non-steroid anti-inflammatory drugs have mostly anticancer effects. Researchers have been especially interested in investigating the association between the use of regional anesthesia techniques and the postoperative survival of patients with cancers. Since the results of the current retrospective studies are conflicting, several researchers are conducting prospective randomized trials.