Analysis of patch testing with cocamidopropyl betaine and its impurities in patients with intractable scalp dermatitis in a single clinic in Japan.

BACKGROUND: The allergen responsible for cocamidopropyl betaine (CAPB) allergies has been debated. OBJECTIVES: To investigate the sensitizing agents of CAPB, the patch test positivity rates of impurities were examined in Japanese patients with CAPB-related allergic contact dermatitis. MATERIALS AND METHODS: Thirty patients with scalp dermatitis and positive patch tests for CAPB and/or lauramidopropyl betaine (LAPB) were enrolled in this study. They were patch tested with the detergents that they had been using at the time of their first visit and with the impurities dimethylaminopropylamine (DMAPA) and lauramidopropyl dimethylamine (LAPDMA). RESULTS: The positivity rate in patch tests of the 37 detergents that the patients had been using was 78.4% (29/37). The positivity rates of DMAPA 1% pet., 1% aq. and 0.2% aq. were 32.1% (9/28), 14.3% (4/28) and 13.3% (4/30), respectively, whereas those of LAPDMA 0.1% and 0.05% were 30.0% (9/30) and 16.7% (5/30), respectively. Among the 30 patients, 6 exhibited positive results for both DMAPA and LAPDMA, 3 showed positive results for DMAPA alone and 6 produced positive results for LAPDMA alone. CONCLUSION: Patch tests produced an overall positivity rate for DMAPA, LAPDMA or both of 50.0% (15/30) in patients with scalp dermatitis and positive patch test results for CAPB and/or LAPB.

Free formaldehyde in non-medical face masks purchased from the Japanese market since the COVID-19 outbreak.

Since the Coronavirus Disease 2019 (COVID-19) pandemic began, people have been wearing face masks for many hours every day. As these face masks are in contact with the skin, it is important to pay more attention to their quality and safety. This study examined the concentration of free formaldehyde in 90 non-medical face masks and related products (33 nonwoven, 30 woven cloth, 12 polyurethane, and 15 related products) because formaldehyde is a common contact allergen in textile products. For products consisting of mixed materials, each material was sampled, resulting in 103 samples for analysis. Free formaldehyde (34-239 µg/g) was found in three cloth masks, which consisted of cotton and polyester, with antibacterial and antiviral labeling. It was confirmed that the detected formaldehyde originated from the mask-finishing treatment by a hydrochloric acid extraction discrimination test. These masks may elicit contact dermatitis if the consumers have already been sensitized to formaldehyde. However, the risk of contact dermatitis caused by formaldehyde in masks may be considered low since the frequency of formaldehyde detection in masks in Japan is low.

Increase of ß2-integrin on adhesion of THP-1 cells to collagen vitrigel membrane.

When human monocyte-derived leukemia (THP-1) cells, which are floating cells, are stimulated with lipid peroxides, or Streptococcus suis, these cells adhere to a plastic plate or endothelial cells. However, it is unclear whether or not non-stimulated THP-1 cells adhere to collagen vitrigel membrane (CVM). In this study, firstly, we investigated the rate of adhesion of THP-1 cells to CVM. When THP-1 cells were not stimulated, the rate of adhesion to CVM was high. Then, to identify adhesion molecules involved in adhesion of THP-1 cells to CVM, expressions of various cell adhesion molecules on the surface of THP-1 cells adhering to CVM were measured. ß-actin, ß-catenin, and ß1-integrin expressions did not change in non-stimulated THP-1 cells cultured on CVM compared with those in cells cultured in a flask, but ß2-integrin expression markedly increased.

Risk assessment of skin lightening cosmetics containing hydroquinone.

Following reports on potential risks of hydroquinone (HQ), HQ for skin lightening has been banned or restricted in Europe and the US. In contrast, HQ is not listed as a prohibited or limited ingredient for cosmetic use in Japan, and many HQ cosmetics are sold without restriction. To assess the risk of systemic effects of HQ, we examined the rat skin permeation rates of four HQ (0.3%, 1.0%, 2.6%, and 3.3%) cosmetics. The permeation coefficients ranged from 1.2 × 10-9 to 3.1 × 10-7 cm/s, with the highest value superior than the HQ aqueous solution (1.6 × 10-7 cm/s). After dermal application of the HQ cosmetics to rats, HQ in plasma was detected only in the treatment by highest coefficient cosmetic. Absorbed HQ levels treated with this highest coefficient cosmetic in humans were estimated by numerical methods, and we calculated the margin of exposure (MOE) for the estimated dose (0.017 mg/kg-bw/day in proper use) to a benchmark dose for rat renal tubule adenomas. The MOE of 559 is judged to be in a range safe for the consumer. However, further consideration may be required for regulation of cosmetic ingredients.

Particle size distribution of aerosols sprayed from household hand-pump sprays containing fluorine-based and silicone-based compounds.

Japan has published safety guideline on waterproof aerosol sprays. Furthermore, the Aerosol Industry Association of Japan has adopted voluntary regulations on waterproof aerosol sprays. Aerosol particles of diameter less than 10 µm are considered as "fine particles". In order to avoid acute lung injury, this size fraction should account for less than 0.6% of the sprayed aerosol particles. In contrast, the particle size distribution of aerosols released by hand-pump sprays containing fluorine-based or silicone-based compounds have not been investigated in Japan. Thus, the present study investigated the aerosol particle size distribution of 16 household hand-pump sprays. In 4 samples, the ratio of fine particles in aerosols exceeded 0.6%. This study confirmed that several hand-pump sprays available in the Japanese market can spray fine particles. Since the hand-pump sprays use water as a solvent and their ingredients may be more hydrophilic than those of aerosol sprays, the concepts related to the safety of aerosol-sprays do not apply to the hand pump sprays. Therefore, it may be required for the hand-pump spray to develop a suitable method for evaluating the toxicity and to establish the safety guideline.

Analysis of isothiazolinone preservatives in polyvinyl alcohol cooling towels used in Japan.

Recently, cases of contact dermatitis that were related to the use of polyvinyl alcohol (PVA) cooling towels containing isothiazolinone preservatives were reported in Japan. The aim of this investigation was to analyze the concentrations of five different isothiazolinone compounds present in PVA towels and to assess the effectiveness of washing in removing the preservatives from new towels prior to being used for the first time. Twenty-seven PVA towels were used in this study. Two groups (i.e., laboratory-simulation and volunteer) of washing experiments were conducted to evaluate the effect of washing procedures. Qualitative and quantitative analyses were performed by LC/MS/MS, which detected 2-methyl-4-isothiazolin-3-one (MI) and 5-chloro-2-methyl-4-isothaizolin-3-one (CMI) in 23 samples (MI: 0.29-154 µg g-wet(-1), CMI: 2.2-467 µg g-wet(-1)), 2-n-octyl-4-isothiazolin-3-one (OIT) in one sample (478 µg g-wet(-1)). The compounds 4,5-Dichloro-2-n-octyl-4-isothiazolin-3-one (2Cl-OIT) and 1,2-benzisothiazolin-3-one (BIT) were not detected in all samples. We confirmed the presence of residual MI, CMI, and OIT in the washed towels, and the residual-to-original content ratio of OIT was higher than that of MI and CMI in PVA towels, due to the higher hydrophobicity of OIT than MI and CMI. A concern has been raised about the occurrence of contact dermatitis being caused by the use of PVA towels. It is suggested that a detailed description of isothiazolinone preservatives in PVA towels and an effective washing procedure for the removal of these preservatives should be provided by the manufacturer. Further, alternative non-sensitizing preservatives might be considered for the manufacture of PVA cooling towels in the future.

[Examination of identification test of certain aromatic amines originating from azo colorants in textile and leather products using high performance liquid chromatography].

Azo colorants that generate primary aromatic amines (PAAs) have been recently deliberated as a controlled harmful substance by the "Act on the Control of Household Products Containing Harmful Substances" in Japan. Therefore, we examined an identification test for 22 kinds of PAAs originating from the azo colorants in commercial textile products and leather products using high performance liquid chromatography (HPLC). When a PAAs standard solution containing 2,4-xylidine and 2,6-xylidine was analyzed using the condition according to EN14362-1:2012 at 240 nm as a basic condition, we observed enough separation for all the PAAs to identify. However, in the some sample solutions, the peaks of several PAAs were overlapped with the interference peaks, and their identifications were difficult. In these cases, some PAAs were able to identify by alteration to suitable wavelength. Furthermore, the retention time of almost PAAs and interference peaks were changed by using acetonitrile as the organic solvent in eluent or phenyl type column. These modifications were helpful for identification of PAA which was overlapped to interference substances by the basic condition. Thus, we suggest the HPLC condition for an identification test is in accordance to that described in EN14362-1:2013. And we propose that the HPLC condition can be modified as necessary.

GC-MS Analysis of Primary Aromatic Amines Originated From Azo Dyes in Commercial Textile or Leather Products Using Helium Alternative Carrier Gases.

BACKGROUND: In recent years, due to the global shortage of helium gas, the development of gas chromatography (GC) analytical methods using alternatives to helium carrier gases is necessary. OBJECTIVE: The objective of this study was to examine the applicability of hydrogen and nitrogen as alternative carrier gases using the test method for azo compounds in the Act on Control of Household Products Containing Harmful Substances of Japan. METHOD: The gas chromatograph mass spectrometer (GC-MS) analytical method using hydrogen and nitrogen as alternative carrier gases was compared with a method using helium for 26 primary aromatic amines (PAAs) originated from azo dyes. RESULTS: When hydrogen and nitrogen were used as carrier gases under the same conditions used during analysis using helium (same column, gas flow rate, oven temperature conditions, etc.), sufficient peak separation of 26 PAAs was obtained. The sensitivities of the methods using helium and hydrogen were comparable, whereas the sensitivity was lower when nitrogen was used, with the detection limits ranging from 1/220 to 1/25. However, all carrier gases achieved quantification at concentrations below the standard value (30 µg/g) of the Act on Control of Household Products Containing Harmful Substances, and the results were in agreement with the standard value for the target product. CONCLUSIONS: Our results indicated that hydrogen or nitrogen can be used as alternative carrier gases to helium for GC-MS analysis of azo compounds producing specific aromatic amines. HIGHLIGHTS: Using hydrogen or nitrogen as an alternative carrier gas to helium, azo compounds could be quantified with excellent accuracy.

[Examination of Analytical Method for Tris(2,3-dibromopropyl)phosphate and Bis(2,3-dibromopropyl)phosphate to Revise the Official Methods Based on "Act on the Control of Household Products Containing Harmful Substances"].

In Japan, the use of frame retardants [tris(2,3-dibromopropyl)phosphate: TDBPP and bis(2,3-dibromopropyl)phosphate: BDBPP] in several household textile products is banned under the "Act on the Control of Household Products Containing Harmful Substances." As the official analytical methods for testing these substances have not been revised for over 42 years, several issues such as the using of harmful reagents, have been pointed out. Therefore, we developed a new method to revise the official method in our previous study. In this study, the validity of the developed test method is evaluated at six laboratories using two types of textile samples spiked with TDBPP and BDBPP at three concentrations (4, 8, and 20 µg/g). TDBPP and BDBPP are extracted under reflux using methanol containing hydrochloric acid. TDBPP is analyzed using GC-MS, and BDBPP is also analyzed using GC-MS after methylation with trimethylsilyl diazomethane. Although the accuracy (70-120%), repeatability (<10%), and reproducibility (<15%) of a few samples, mainly low concentration samples, are out of range, overall, the concentration level of detection limits of TDBPP and BDBPP (8 and 10 µg/g) in official analytical methods are quantifiable with sufficient precision using the proposed method. Furthermore, harmful reagents are not used in this method. Thus, the method validated in this study is effective as a revised method for the testing of TDBPP and BDBPP in household textile products.

[Characterization of cases contravening of regulations regarding primary aromatic amines originating from azo dyes in commercial textile products and leather products in European Union].

Contraventions of regulations regarding primary aromatic amines (PAAs) originating from azo dyes in commercial textile products and leather products in European Union (EU), notified in the period between 2006 and 2012 were collected from the Rapid Alert System for non-food consumer products (RAPEX), were characterized. Various types of products (clothes, footwear, bedding, etc.) and their raw materials (cotton, silk, viscose, leather, etc.) were reported to have contravened the regulations. The contravention frequencies for products made in China and India were higher than those for other countries. Ten percentage of the country in which the reported products were produced was unknown. The notification frequencies for benzidine and 4-aminoazobenzene were higher than those for other PAAs. Contravention of regulations regarding benzidine, 4-aminoazobenzene, and 3,3'-dimethoxybenzidine were notified every year. Contraventions of regulations regarding five PAAs--classified as IARC group 1--were notified one or several times. Since the scale of the survey conducted in Japan were small compared with RAPEX, it is necessary that many kinds and number of products should be surveyed in Japan. In addition, it is also necessary to pay attention to 4-aminoazobenzene, while it has not been detected in the previous studies conducted in Japan.

A step-by-step approach for assessing acute oral toxicity without animal testing for additives of quasi-drugs and cosmetic ingredients.

Animal testing of cosmetic ingredients and products has been banned in the European Union since 2013. However, in Japan, the application of new quasi-drugs requires the generation of data on acute oral toxicity through animal testing. A weight of evidence approach for assessing oral toxicity was challenged. This approach used a combination of safety data, including a neutral red uptake cytotoxicity assay using BALB/c3T3 cells (3T3-NRU cytotoxicity assay), which can assess the acute oral toxicity of quasi-drugs or cosmetic ingredients. We conclude that the step-by-step approach can be used to assess test substances that cause low acute oral toxicity, such as the median lethal dose (LD 50) > 2000 mg/kg, thereby avoiding animal testing.

Measurement of skin permeation/penetration of nanoparticles for their safety evaluation.

The aim of the present study was to quantitatively evaluate the skin permeation/penetration of nanomaterials and to consider their penetration pathway through skin. Firstly, penetration/permeation of a model fluorescent nanoparticle, Fluoresbrite®, was determined through intact rat skin and several damaged skins. Fluoresbrite® permeated through only needle-punctured skin. The permeation profiles of soluble high molecular compounds, fluorescein isothiocyanate-dextrans (FITC-dextrans, FDs), with different molecular weights were also measured for comparison. The effects of molecular sizes and different skin pretreatments on the skin barrier were determined on the skin penetration/permeation of Fluoresbrite® and FDs. Fluoresbrite® was not permeated the intact skin, but FDs were permeated the skin. The skin distribution of titanium dioxide and zinc oxide nanoparticles was also observed after topical application of commercial cosmetics. Nanoparticles in sunscreen cosmetics were easily distributed into the groove and hair follicles after their topical application, but seldom migrated from the groove or follicles to viable epidermis and dermis. The obtained results suggested that nanoparticles did not permeate intact skin, but permeated pore-created skin. No or little permeation was observed for these nanomaterials through the stratum corneum.

Determination of Carcinogenic Primary Aromatic Amines Contained as Impurities in Synthetic Organic Colorants.

BACKGROUND: Several primary aromatic amines (PAAs) have been designated carcinogenic or suspected of carcinogenicity. Several kinds of PAAs may occur either via the reduction of azo compounds or as impurities in azo colorants or other agents. OBJECTIVE: An analytical method was developed and applied to determine whether certain PAAs are present as impurities in synthetic organic colorants. METHOD: Target chemicals were analyzed by the ultrasound extraction of the synthetic organic colorant with a hydrochloric acid solution containing 20% methanol, followed by conversion from an acidic to alkaline solution, and then extraction using a diatomaceous earth column. RESULTS: We analyzed certain PAAs in 38 synthetic organic colorants, resulting in the detection of 2,4-dimethylaniline in four samples at 1.2 to 19 µg/g, o-toluidine in three samples at 1.0 to 3.4 µg/g, p-phenylazoaniline in two samples at 74 to 305 µg/g, and, in one sample each, 2,4,5-trimethylaniline (13 µg/g), 5-nitro-o-toluidine (12 µg/g), and 2-methyl-4-(2-tolylazo)aniline (13 µg/g). Nearly all PAAs were determined to be starting materials for colorant synthesis, although p-phenylazoaniline in Yellow No. 407 was apparently a byproduct formed during synthesis. For Red No. 225, in which high concentrations of p-phenylazoaniline were detected, additional samples were purchased from five companies, and p-phenylazoaniline was detected at concentrations of 88 to 370 µg/g in all samples. CONCLUSIONS: A method to analyze certain PAAs contained as impurities in synthetic organic colorants was developed, and the actual status of them in colorants was clarified. HIGHLIGHTS: The analytical method developed in this study for the determination of certain PAAs contained as impurities in synthetic organic colorants may be used to improve the safety of colorants.

Characterization of synthetic turf rubber granule infill in Japan: Volatile organic compounds.

There has been extensive studies on the composition of tires and industrial rubber. However, there is insufficient information on volatile organic compounds (VOCs) emitted from rubber granule products used to fill synthetic turf fields. In this study, we applied a passive sampling method for assessing the VOCs emitted from rubber granule products used for filling synthetic turf fields. We also performed a quantitative component analysis using a gas chromatography-mass spectrometer (GC-MS). The component analysis results of 46 rubber granule-based products showed the predominant presence of benzothiazole and methyl isobutyl ketone. The level of benzene, which the International Agency for Research on Cancer classifies as a substance with sufficient evidence for carcinogenicity to humans, was below the lower quantification limit in the products tested in this study. Our study included most of the rubber granule products used for synthetic turf fields in Japan (>95% of the products in the current domestic market of Japan). Therefore, we obtained a comprehensive overview of the VOCs emitted from the rubber granule-based products used in Japan's synthetic turf fields. Estimating the exposure to these airborne VOCs is essential to evaluate the adverse health effects of the VOCs emitted from these rubber granule-based products. Our sampling method and results can help provide key data for such risk assessment studies in the future.

Characterization of synthetic turf rubber granule infill in Japan: Total content and migration of metals.

We evaluated the total content of 28 metals in synthetic turf rubber granule infill and performed extraction tests using four types of simulated biofluids to assess the health effects of synthetic turf crumb rubbers used in Japan. The highest median metal concentration was obtained for Zn, with median concentrations above 100 µg/g, followed by Al, Fe, and Mn. The highest median Pb concentration was 19.9 µg/g. The metal concentrations of the samples were different depending on the origin/material. Among high-concentration metals, Al, Fe, and Mn were higher in ethylene propylene diene monomer rubber, and Zn was higher in tires. Significantly higher Sb and Sr concentrations were observed in other materials, including industrial rubber, synthetic rubber, and thermoplastic elastomer, compared with tires. However, significantly higher Sn, Co, Pb, and Cd concentrations were detected in tires compared with other materials. Metals with high concentrations independent of the origin/material were considered derived from materials added during the manufacturing process. To evaluate the bioaccessibility, extraction tests were conducted using simulated biofluids. In gastric fluid, many metals were detected in higher concentrations than in other biofluids, intestinal fluid, saliva, and sweat, and the extraction rate of most metals exceeded 10% in artificial gastric fluid. Because the amount of metals leached into the simulated biofluids was much lower than several standards on the amount of certain metals that have the potential to be extracted from the object if ingested, the risk related to the exposure to metals from synthetic turf rubber granule infill is considered low.

Characterization of synthetic turf rubber granule infill in Japan: Polyaromatic hydrocarbons and related compounds.

Although the health effects of artificial turf fillings have been investigated in Europe and the United States, the actual situation in Japan is unclear. To address this issue, the concentrations of 46 polyaromatic hydrocarbons (PAHs) and related compounds in rubber infills were analyzed prior to their use in synthetic turf fields in Japan. Based on information obtained from the sample suppliers, the investigated samples were divided into five categories: discarded tires, industrial rubber, combinations of these products or unidentified components (mixture/unknown), synthetic rubber specifically manufactured for synthetic turf, and special-purpose thermoplastic elastomers (TPEs). The industrial rubber samples were mixtures of styrene butadiene rubber, natural rubber, and ethylene propylene diene rubber (EPDM). The synthetic rubber samples consisted only of EPDM. A few or none of the PAHs were detected in the synthetic rubber and TPE samples. However, in the discarded tire and industrial rubber samples, benzo[a]pyrene, cyclopenta[cd]pyrene, and 30 other compounds were detected. A comparison between these two categories indicated that the discarded tire samples exhibited higher concentrations of the target compounds than the industrial rubber samples. This finding can be attributed to the presence of EPDM in almost all of the industrial rubber samples, which were not present in the discarded tire samples. The maximum PAH concentrations obtained in the present study were equivalent to or lower than the previously reported PAH concentrations. The total concentrations of the eight PAHs included in the European Chemical Agency (ECHA) assessment of health risks were lower in the present study than those reported by the ECHA. Furthermore, elution testing was performed with four simulated biofluids (gastric and intestinal juices, saliva, and perspiration). The actual elution amounts of all compounds were less than the limits. This report provides basic data for the risk assessment of PAHs in rubber infills.

Characterization of synthetic turf rubber granule infill in Japan: Rubber additives and related compounds.

We have conducted several studies with an overall goal of assessing the effects of rubber granules in synthetic turf on the health of athletes, other players, and children in Japan. As part of these studies, the investigation reported herein was aimed at analyzing the concentrations of rubber additives (vulcanization accelerators, antioxidants, and cross-linking agents) and related chemicals in 46 rubber infills prior to their use in synthetic turf fields in Japan. Of the 36 chemicals selected for targeted analysis, 26 were detected and quantified. Nontargeted analyses further identified and quantified 16 compounds derived from vulcanization accelerators, plasticizers, and other additives. The types and concentrations of the detected compounds varied both between products and within the same product; in the case of rubber infill products made from recycled rubber, this variation was caused by the different types of rubber products recycled as raw materials. Elution tests with four simulated biofluids (gastric juice, intestinal juice, saliva, and perspiration) revealed that the elution rates varied between compounds and were affected by the presence of coatings. Most compounds had low elution rates in all the simulated biofluids, with many at or below the limit of quantification. The data reported herein will be utilized in the risk characterization part of our subsequent study on the health risk assessment of rubber infill.

A cell-based evaluation of human tyrosinase-mediated metabolic activation of leukoderma-inducing phenolic compounds.

BACKGROUND: Chemical leukoderma is a skin depigmentation disorder induced through contact with certain chemicals, most of which have a p-substituted phenol structure similar to the melanin precursor tyrosine. The tyrosinase-catalyzed oxidation of phenols to highly reactive o-quinone metabolites is a critical step in inducing leukoderma through the production of melanocyte-specific damage and immunological responses. OBJECTIVE: Our aim was to find an effective method to evaluate the formation of o-quinone by human tyrosinase and subsequent cellular reactions. METHODS: Human tyrosinase-expressing 293T cells were exposed to various phenolic compounds, after which the reactive o-quinones generated were identified as adducts of cellular thiols. We further examined whether the o-quinone formation induces reductions in cellular GSH or viability. RESULTS: Among the chemicals tested, all 7 leukoderma-inducing phenols/catechol (rhododendrol, raspberry ketone, monobenzone, 4-tert-butylphenol, 4-tert-butylcatechol, 4-S-cysteaminylphenol and p-cresol) were oxidized to o-quinone metabolites and were detected as adducts of cellular glutathione and cysteine, leading to cellular glutathione reduction, whereas 2-S-cysteaminylphenol and 4-n-butylresorcinol were not. In vitro analysis using a soluble variant of human tyrosinase revealed a similar substrate-specificity. Some leukoderma-inducing phenols exhibited tyrosinase-dependent cytotoxicity in this cell model and in B16BL6 melanoma cells where tyrosinase expression was effectively modulated by siRNA knockdown. CONCLUSION: We developed a cell-based metabolite analytical method to detect human tyrosinase-catalyzed formation of o-quinone from phenolic compounds by analyzing their thiol-adducts. The detailed analysis of each metabolite was superior in sensitivity and specificity compared to cytotoxicity assays for detecting known leukoderma-inducing phenols, providing an effective strategy for safety evaluation of chemicals.

Survival of SARS-CoV-2 and bovine coronavirus on common surfaces of living environments.

Aerosols or saliva containing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can contaminate living environments, and viruses can be indirectly transmitted. To understand the survival potential of the virus, the viral titers of bovine coronavirus (BCoV), as a model virus, and SARS-CoV-2 were measured on porous and non-porous surfaces. The amount of infectious BCoV recovered remained relatively high on non-porous substrates. However, it quickly decreased on several non-porous surfaces such as nitrile rubber. The time taken to reach the limit of detection on non-woven masks, as a porous substrate, was longer than that of non-porous substrates. On porous substrates other than non-woven masks, the amount of virus recovered quickly decreased, and then remained at a low level. Representative substrates were tested with SARS-CoV-2. The decrease in the amount of infectious virus recovered was similar to that of BCoV, although that of SARS-CoV-2 was more rapid. RNA derived from SARS-CoV-2 was also detected using real-time PCR, and it remained on surfaces much longer than infectious virus, on all substrates. Therefore, it is important to measure the viral titer to avoid the overestimation of infectious virus contamination in the environments. Our results suggest that the surface structure was not directly related to viral survivability.