Study of the soothing effects of troxerutin in alleviating skin sensitivity.

BACKGROUND: Transient receptor potential vanilloid 1 (TRPV1) is associated with skin sensitivity and mainly activated by capsaicin and heat. Interestingly, troxerutin can inhibit TRPV1 activation. However, its efficacy in reducing skin sensitivity remains undetermined. AIMS: We evaluated the efficacy of troxerutin in alleviating skin sensitivity using clinical tests and in vitro experiments. METHODS: For the in vitro experiment, HaCaT keratinocytes were pretreated with different concentrations of troxerutin, followed by incubation with 50 µM capsaicin for 1, 24, or 48 h. The gene and protein expressions of four inflammatory cytokines involved in skin irritation were determined. Among 35 Korean women with sensitive skin recruited for the clinical trial, 13 were involved in assessing the immediate soothing effects of 0.1% and 0.0095% troxerutin following capsaicin irritation, whereas 22 participated in evaluating the preventive soothing effect of 10% and 1% troxerutin over 4 weeks against capsaicin- and heat-induced irritation. We evaluated the soothing rate using skin redness, visual analog scale, and high temperature sensitive index as evaluation indices. RESULTS: Troxerutin inhibited the mRNA and protein expressions of cytokines in capsaicin-treated keratinocytes. In the clinical study, 0.1% and 0.0095% troxerutin promptly alleviated capsaicin-induced skin redness, whereas 10% troxerutin notably decreased both the visual analog scale and high temperature sensitive index for capsaicin- and heat-related irritation. However, 1% troxerutin was only effective in reducing the visual analog scale in response to capsaicin irritation. CONCLUSIONS: Troxerutin can inhibit TRPV1 activation in clinical and in vitro tests.

Occurrence and geochemistry of altered radioactive accessory minerals as sources of radionuclide in Mesozoic granite aquifers (Korea).

Accessory minerals in granitic rocks are unlikely significant radionuclide contributions to groundwater due to their remarkable durability. However, accessory minerals incorporating U and Th may suffer structural damages due to the radioactivity and become highly susceptible to alteration. This study investigates geochemistry coupled with textural analysis of the U-Th bearing accessory minerals using a field emission scanning electron microscope and an electron probe micro-analyzer. Altered zircons with numerous open structures related to the radioactive decay show higher contents of U and Th and low analytical totals. Some thorites show high contents of U and non-formula elements due to the hydrothermal alteration in the metamicted thorite. The cerianite including U occurs as micro-veinlet in fracture with trace of Fe and Mn oxides, which indicates secondary phase formation from the decomposed accessory minerals in an oxidizing environment. Some accessory minerals with the high content of U and Th have been found in Mesozoic granite terrain in South Korea, where high concentration levels of radionuclide in groundwater were also reported. The leaching of U may be more likely when the accessory minerals are highly metamicted or altered as found in our samples. The altered zircon and thorite of the study area could be major carriers of radioelement in Mesozoic granitic aquifers where the occurrence of soluble U-minerals has not been reported.

Penetration rates into the stratum corneum layer: A novel quantitative indicator for assessing skin barrier function.

BACKGROUND: The stratum corneum (SC), the outermost layer of the skin epidermis, acts as an effective bi-directional barrier, preventing water loss (inside-outside barrier) and entry of foreign substances (outside-inside barrier). Although transepidermal water loss (TEWL) is a widely-used measure of barrier function, it represents only inside-outside protection. Therefore, we aimed to establish a non-invasive method for quantitative evaluation of the outside-inside barrier function and visually present a skin barrier model. MATERIALS AND METHODS: Skin barrier damage was induced by applying a closed patch of 1% sodium dodecyl sulfate to the forearms of eight participants; they were instructed to apply a barrier cream on a designated damaged area twice daily for 5 days. The SC barrier was evaluated by measuring TEWL and fluorescein sodium salt penetration rate before, immediately after, and 5 days after damage. The penetration rate was assessed using tape-stripping (TS) technique and fluorescence microscopy. RESULTS: The rates of fluorescein sodium salt penetration into the lower layers of SC differed significantly based on the degree of skin barrier damage. The correlation between penetration rate and TEWL was weak after two rounds of TS and became stronger after subsequent rounds. Five days after skin barrier damage, the penetration rate of all layers differed significantly between areas with and without the barrier cream application. CONCLUSION: Our findings demonstrated that the penetration rate was dependent on skin barrier conditions. The penetration rate and corresponding fluorescence images are suitable quantitative indicators that can visually represent skin barrier conditions.

Neurobehavioral effects of the exposure to mercury vapor and methylmercury during postnatal period on mice.

In this study, we investigated the neurobehavioral alterations and modifications of gene expression in the brains of female mice exposed to low-level mercury vapor and/or methylmercury during postnatal development. The mice were exposed to low-level mercury vapor at a mean concentration of 0.094 mg/m3 and supplied with tap water containing 5 ppm methylmercury from postnatal day 11 to 12 weeks of age. Behavioral analyses were performed at 17 weeks of age. Total locomotor activity in the open field test and the retention trial performance in the passive avoidance test were significantly reduced in the combined exposure group compared with those in the control group. The differences in locomotor activity and performance in the retention trial at 17 weeks were no longer detected at 45 weeks. These results suggest that the effect of aging on the behavioral abnormalities resulting from postnatal exposure to mercury complexes are not significant. In the microarray analysis of brains in the combined exposure group, the gene expression levels of Ano2 and Sgk1 were decreased. Real-time RT-PCR analysis confirmed these changes caused by combined mercury exposure, showing significant downregulation of Ano2 and Sgk1 in the cerebrum. These genes play key roles in the brain as a calcium-activated chloride channel and as a kinase that responds to cellular stress, respectively. Our findings provide insight into the neurobehavioral changes caused by combined mercury exposure.

Hydrogeological characteristics and water chemistry in a coastal aquifer of Korea: implications for land subsidence.

Land subsidence is the gradual or sudden dropping of the ground surface developed by increasing the total stress. Most studies have discussed the relationship between land subsidence with groundwater level. However, there is a lack of discussion on groundwater environmental changes after occurring land subsidence. This study aimed to evaluate the hydrogeological and water chemistry characteristics of construction sites with land subsidence. Land subsidence in the Yangyang coastal area occurred suddenly on August 3, 2022, when the retaining wall of the construction collapsed. The groundwater level was measured three times, and water samples were collected twice between August 5, 2022, and September 5, 2022, for laboratory analysis. After land subsidence occurred, the average groundwater level was - 19.91 m ground level (GL) on August 9, 2022, and finally decreased to - 19.21 m GL on September 05, 2022. The groundwater levels surrounding the construction site gradually increased for a month. The electrical conductivity value measured at the monitoring wells ranged from 89 to 7800 µS/cm, and four wells exceeded the measurement limit near the groundwater leaked points. The highest mixing ratio of leaked water samples, collected on August 9, 2022, was 27.6%. Furthermore, the fresh groundwater-saltwater interface depth was estimated to be above the construction bottom. Although groundwater levels recovered, the groundwater quality continuously is affected by saltwater. This finding could contribute to understanding the hydrogeological characteristics surrounding construction sites with land subsidence and provide insight into the hydrochemical evolution process during declined groundwater levels in coastal aquifers.

Long-Term Exposure to Cadmium Causes Hepatic Iron Deficiency through the Suppression of Iron-Transport-Related Gene Expression in the Proximal Duodenum.

Cadmium (Cd) is an environmental pollutant that damages various tissues. Cd may cause a depletion of iron stores and subsequently an iron deficiency state in the liver. However, the molecular mechanism of decreased iron accumulation in the liver induced by long-term exposure to Cd is unknown. In this study, we investigated the hepatic accumulation of iron and the proximal duodenal expression of the genes involved in iron transport using mice chronically exposed to Cd. Five-week-old female C57BL/6J mice were fed a diet containing 300 ppm Cd for 12, 15, 19 and 21 months. The iron concentration in the liver was markedly decreased by Cd. Among iron-transport-related genes in the proximal duodenum, the gene expression of HCP1 and Cybrd1 was significantly decreased by Cd. HCP1 is an influx transporter of heme iron. Cybrd1 is a reductase that allows non-heme iron to enter cells. The expression of iron-transport-related genes on the duodenal basolateral membrane side was hardly altered by Cd. These results suggest that long-term exposure to Cd suppresses the expression of HCP1 and Cybrd1 in the proximal duodenum, resulting in reduced iron absorption and iron accumulation in the liver.

Microplastic contamination in groundwater of rural area, eastern part of Korea.

Microplastics (MPs) are emerging contaminants in agricultural regions owing to the widespread use of plastics in farming activities. Groundwater has a vital role in farming activities, and it can be contaminated by MPs, fragmented from plastic products used in agricultural activities. Following an appropriate sampling protocol, this study investigated the distribution of MPs in shallow to deep aquifers (well depths: 3-120 m) and cave water of an agricultural region in Korea. Our investigation found that MPs contamination can penetrate up to the deep bedrock aquifer. The abundance of MPs was lower during the wet season (0.014-0.554 particles/L) than during the dry season (0.042-1.026 particles/L), which may be attributed to the dilution effect of precipitation in the groundwater. The abundance of MPs increased as the MPs size decreased at all sampling points, and size ranges were 20.3-869.6 and 20.3-673.0 µm in the dry and wet seasons, respectively. Our findings showed lower MPs abundance compared to previous studies, and we inferred that it might be due to differences in groundwater sampling volume, low agricultural intensity, and the non-application of sludge fertilizers. Our findings suggest that repeated and long-term investigations are needed to identify better the factors that influence the results of MPs distribution in groundwater, including sampling methods and hydrogeological and hydrological conditions.

Effect of aging on polyethylene microfiber surface properties and its consequence on adsorption characteristics of 17alpha-ethynylestradiol.

This study assessed the interactive changes to the endocrine disruptor 17 alpha-ethynylestradiol (EE2) triggered by photoaging onto fibrous microplastics frequently found in the environment. The physicochemical property change of the polyethylene (PE) microfiber according to irradiation (i.e. 14 d UV-C (254 nm)) was studied through Fourier transform infrared spectroscopy, scanning electron microscope, and contact angle analysis. Additionally, the EE2 adsorption kinetics experiment was performed for the PE microfiber before and after UV irradiation to assess the change in adsorption characteristics. After UV irradiation, the PE microfiber surface roughness increased, the oxygen-containing functional group (e.g. carbonyl group) increased, and the contact angle (virgin PE: 80.02°, aged PE: 65.13°) decreased. A decrease in the surface hydrophobicity led to a decrease in the adsorption rate of EE2 (virgin PE: k = 0.0105 h-1, aged PE: not calculated). The hydrophobic interaction significantly affects the adsorption behavior of hydrophobic organic pollutants such as EE2 onto MPs, and continuous photo-aging of MPs may cause a new pattern of ecological risk. Therefore, there is a greater necessity for additional research relevant to this issue.

Role of soil microplastic pollution in climate change.

In recent decades, environmental pollution from microplastic (MPs: <5 mm) and climate change have received international attention. However, these two issues have been primarily investigated separately hitherto, although they exhibit a cause-and-effect relationship. Studies considering MPs and climate change as causal entities have focused only on MP pollution in marine environments as a contributor to climate change. Meanwhile, systematic causal studies have not been performed inadequately to understand the role of soil, which is a primary terrestrial sink of greenhouse gases (GHGs) in the context of MP pollution, in climate change. In this study, the causal effect of soil MP pollution on GHG emissions as direct and indirect contributors to climate change is systematically analyzed. The mechanisms underlying the contribution of soil MPs to climate change are discussed, and future research perspectives are suggested. Approximately 121 research manuscripts pertaining to MP pollution and its associated effects on GHGs, carbon sinks, and soil respiration, recorded between 2018 and 2023, are selected and cataloged from seven database categories in PubMed, Google Scholar, Nature's database, and Web of Science. Several studies demonstrated that soil MP pollution directly contributes to climate change by accelerating the emission of GHGs from the soil to the atmosphere and indirectly by promoting soil respiration and adversely affecting natural carbon sinks, such as trees. Other studies correlated the release of GHGs from the soil to mechanisms such as the alteration of soil aeration, methanogen activity, and carbon and nitrogen cycles, and improved the abundance of carbon and nitrogen soil microbial functional genes adhering to plant roots to create anoxic conditions for plant growth. In general, soil MP pollution increases the release of GHGs into the atmosphere, thereby contributing to climate change. However, further research is to be conducted by investigating the underlying mechanisms using more practical field-scale data.

Methylmercury directly modifies the 105th cysteine residue in oncostatin M to promote binding to tumor necrosis factor receptor 3 and inhibit cell growth.

We previously found that methylmercury induces expression of oncostatin M (OSM), which is released extracellularly and binds to tumor necrosis factor receptor 3 (TNFR3), possibly enhancing its own toxicity. However, the mechanism by which methylmercury causes OSM to bind to TNFR3 rather than to its known receptors, OSM receptor and LIFR, is unknown. In this study, we aimed to elucidate the effect of methylmercury modification of cysteine residues in OSM on binding to TNFR3. Immunostaining of TNFR3-V5-expressing cells suggested that methylmercury promoted binding of OSM to TNFR3 on the cell membrane. In an in vitro binding assay, OSM directly bound to the extracellular domain of TNFR3, and this binding was promoted by methylmercury. Additionally, the formation of a disulfide bond in the OSM molecule was essential for the binding of both proteins, and LC/MS analysis revealed that methylmercury directly modified the 105th cysteine residue (Cys105) in OSM. Next, mutant OSM, in which Cys105 was replaced by serine or methionine, increased the binding to TNFR3, and a similar effect was observed in immunoprecipitation using cultured cells. Furthermore, cell proliferation was inhibited by treatment with Cys105 mutant OSMs compared with wildtype OSM, and this effect was cancelled by TNFR3 knockdown. In conclusion, we revealed a novel mechanism of methylmercury toxicity, in which methylmercury directly modifies Cys105 in OSM, thereby inhibiting cell proliferation via promoting binding to TNFR3. This indicates a chemical disruption in the interaction between the ligand and the receptor is a part of methylmercury toxicity.

The forgotten impacts of plastic contamination on terrestrial micro- and mesofauna: A call for research.

Microplastics (MP) and nanoplastics (NP) contamination of the terrestrial environment is a growing concern worldwide and is thought to impact soil biota, particularly the micro and mesofauna community, by various processes that may contribute to global change in terrestrial systems. Soils act as a long-term sink for MP, accumulating these contaminants and increasing their adverse impacts on soil ecosystems. Consequently, the whole terrestrial ecosystem is impacted by microplastic pollution, which also threatens human health by their potential transfer to the soil food web. In general, the ingestion of MP in different concentrations by soil micro and mesofauna can adversely affect their development and reproduction, impacting terrestrial ecosystems. MP in soil moves horizontally and vertically because of the movement of soil organisms and the disturbance caused by plants. However, the effects of MP on terrestrial micro-and mesofauna are largely overlooked. Here, we give the most recent information on the forgotten impacts of MP contamination of soil on microfauna and mesofauna communities (protists, tardigrades, soil rotifers, nematodes, collembola and mites). More than 50 studies focused on the impact of MP on these organisms between 1990 and 2022 have been reviewed. In general, plastic pollution does not directly affect the survival of organisms, except under co-contaminated plastics that can increase adverse effects (e.g. tire-tread particles on springtails). Besides, they can have adverse effects at oxidative stress and reduced reproduction (protists, nematodes, potworms, springtails or mites). It was observed that micro and mesofauna could act as passive plastic transporters, as shown for springtails or mites. Finally, this review discusses how soil micro- and mesofauna play a key role in facilitating the (bio-)degradation and movement of MP and NP through soil systems and, therefore, the potential transfer to soil depths. More research should be focused on plastic mixtures, community level and long-term experiments.

Microplastic contamination in groundwater on a volcanic Jeju Island of Korea.

Microplastic (MPs) contamination in groundwater has received massive attention since plastic waste has been released directly into the environment. This study investigates MPs contamination in groundwater on the Jeju volcanic Island, Korea. To the best of our knowledge, this is the first study to identify MPs in groundwater from volcanic islands. A total of 21 sites were sampled for groundwater wells and springs in July and September (2021). Sampling was performed without cross-contamination through quality assurance and quality control. The results showed that MPs abundance ranged from 0.006 to 0.192 particles/L in groundwater samples. Additionally, MPs were detected in deep groundwater wells where the groundwater level was 143 m below ground surface. Eight MPs polymer types, including polypropylene, polyethylene, polyethylene terephthalate, polyvinyl chloride, polystyrene, polyamide, acrylonitrile butadiene styrene, and polyurethane, were detected using Micro-Fourier Transform Infrared Spectroscopy (µ-FT-IR). Most of the detected MPs size ranged from 20 to 100 µm, accounting for 95% of the total. Fragments and fiber shaped MPs were detected, with the majority of them being fragmented in groundwater samples. The concentrations of MPs and major ions in groundwater showed a positive correlation. A negative correlation was observed between MPs concentration and topographic elevation (r = -0.59, p = 0.01). The source of MPs contamination is most likely attributed to agricultural activities, such as plastic mulching and greenhouses, which account for most of the land use in the study area. In this study, MPs entered the aquifer through the soil at the surface and seeped through cracks in fractured rock on basalt with sealed groundwater wells. This study takes 500 L of samples to prevent sample bias, reveal plastic contamination in groundwater, and indicating the characteristics and sources of contaminated plastics.

Kinetics of polystyrene nanoplastic deposition on SiO2 and Al2O3 surfaces: Ionic strength effects.

Nanoplastic pollution is an emerging environmental threat to the critical zone. The transport of nanoplastic particles in subsurface environments can be determined mainly by soil minerals because they provide surfaces that interact with nanoplastic particles. However, the interactions between mineral surfaces and nanoplastics are poorly understood. In this study, the deposition kinetics of polystyrene-nanoplastic particles onto representative oxide surfaces SiO2 and Al2O3 at circumneutral pH were investigated using a quartz crystal microbalance, with variations in the ionic strength (0.1-100 mM) of the well-dispersed nanoplastic particles suspension. While polystyrene-nanoplastic particles deposited minimally on the SiO2 surface at an ionic strength of < 100 mM (∼10 ng/cm2), substantial deposition occurred at 100 mM (3.7 ± 0.4 µg/cm2). On the Al2O3 surface, a significant amount of polystyrene-nanoplastic particle was deposited from the lowest ionic strength (4.5 ± 0.8 µg/cm2). The deposition mass at 100 mM NaCl was two times higher (7.2 ± 0.2 µg/cm2) than on the SiO2 surface, while the deposition rates were similar between the two surfaces (10-15 Hz/min). Our results indicate that alumina most likely exerts a stronger influence than quartz on the transport of nanoplastic particles in soils and groundwater aquifers. The deposition kinetics strongly depends on the mineral surface and solution ionic strength, and these quantitative results can serve as validation data in developing transport modeling of nanoplastic in subsurface environments.

Microplastics contamination and characteristics of agricultural groundwater in Haean Basin of Korea.

The quality of groundwater is critical to human health. MPs have access to groundwater from the soil, polluted by various agricultural activities. However, to date, there have been no studies on the occurrence of MP in groundwater from an agriculture field without any adjacent sources of contamination, such as nearby landfills. In this study, the occurrence and distribution of MPs in groundwater of an agricultural area in the Haean Basin, Korea, without any definite source of pollution, was examined. MP and groundwater samplings were conducted in the dry season in 2020, the wet and dry seasons in 2021, respectively. In this study, the reliability of MP analysis was improved through good practices from laboratory to field campaigns, collecting large groundwater samples (300-500 L) volumes. Any involvement of plastic materials was avoided during the full procedures as possible and. Detailed investigation was conducted for the distribution of potential plastics sources like mulching, plastic covers, dripping pipes and shading nets, and hydrogeological properties affecting MPs occurrence. Groundwater MP concentrations of 0.02-0.15 particles/L (median = 0.06 particles/L), 0.02-2.56 particles/L (median = 0.43 particles/L) and 0.20-3.48 particles/L (median = 0.83 particles/L) were found in three rounds of sampling that comprised of the exploratory investigation in 2020, the wet season, and the dry season in 2021, respectively. The identified polymer types were polypropylene (PP), polyethylene (PE), polyvinyl chloride (PVC), polystyrene (PS) and polyamide (PA). The MPs concentrations showed no statistically significant seasonal variation but revealed an apparent strong positive correlation (r = 0.71) of MPs with the amount of groundwater use. Findings of this study need more clarification from repeated samplings for multiple years. This study reveals the occurrence of MPs in groundwater in Korea for the first time to the best of our knowledge.

Microplastics in soil and freshwater: Understanding sources, distribution, potential impacts, and regulations for management.

Plastic debris is a complex and persistent environmental contaminant that has received a high amount of attention in the last few years. Understanding the sources, transport, fate, occurrence, and health risks of microplastics (MPs) in the environment is essential as millions of tons of plastic are manufactured and released into the environment. There is a high possibility that MPs will accumulate and retain within continental environments and have effects on the environment and human health. This review elucidates the outcomes of studies related to the prevalence, transport, fate, and health risks of MPs in soil and freshwater environments. The review shows that the sources of MPs are diverse and extensive and their occurrence, transport, fate, and health risks in the environment are affected by their physico-chemical characteristics and by natural factors. Implemented legislation or regulatory plans to reduce MPs contamination of the environment have been reviewed in this study. Moreover, management options are presented.

Cadmium Toxicity Is Regulated by Peroxisome Proliferator-Activated Receptor δ in Human Proximal Tubular Cells.

Cadmium (Cd) is a toxic heavy metal that is widely present in the environment. Renal proximal tubule disorder is the main symptom of Cd chronic poisoning. Our previous study demonstrated that Cd inhibits the total activities of peroxisome proliferator-activated receptor (PPAR) transcription factors in human and rat proximal tubular cells. In this study, we investigated the involvement of PPAR in Cd renal toxicity using the HK-2 human proximal tubular cell line. Among PPAR isoform genes, only PPARD knockdown significantly showed resistance to Cd toxicity in HK-2 cells. The transcriptional activity of PPARδ was decreased not only by PPARD knockdown but also by Cd treatment. DNA microarray analysis showed that PPARD knockdown changed the expression of apoptosis-related genes in HK-2 cells. PPARD knockdown decreased apoptosis signals and caspase-3 activity induced by Cd treatment. PPARD knockdown did not affect the intracellular Cd level after Cd treatment. These results suggest that PPARδ plays a critical role in the modification of susceptibility to Cd renal toxicity and that the apoptosis pathway may be involved in PPARδ-related Cd toxicity.

Novel human skin surface antimicrobial peptide quantification method using a skin patch test chamber: A pilot study.

INTRODUCTION: Antimicrobial peptides (AMPs) on the skin surface are related to the innate immunity of the skin in preventing external infection. Skin rinsing and tape stripping (TS) are acceptable methods for analyzing AMPs on the skin surface but have limitations, such as causing skin damage. In this study, we proposed a noninvasive method to measure AMPs on the skin surface with minimal skin damage. METHODS: Using the patch test assay, we aimed to analyze the skin surface human ß-defensin (hBDs) levels without damaging the skin barrier. The concentrations of hBDs on the skin surface were evaluated through the skin patch testing of 13 healthy subjects, and hBD-1 concentrations were compared with those obtained using the TS method in this proof-of-concept study. In addition, changes in skin physiology and concentration of hBDs under 1% sodium lauryl sulfate stimulation were monitored in 14 healthy subjects (8 young and 6 elderly subjects) for 150 h. RESULTS: The correlation between the two methods had a Pearson's coefficient of 0.640, and skin patch analysis led to a relatively less impaired barrier with no significant increase in transepidermal water loss after analysis. Age-specific comparisons suggested that higher skin surface hBD-2 concentrations were present in the young group as compared with the elderly group. Skin surface expression of hBD-2 after skin barrier disruption was also higher in the young group. CONCLUSION: Our findings show that skin patch analysis is a convenient method to analyze hBDs on the skin surface. hBDs are factors of innate immunity that can be used as an index to predict a decreased chemical immune response of skin due to aging.

Good field practice and hydrogeological knowledge are essential to determine reliable concentrations of microplastics in groundwater.

There are some weaknesses in the methodology of original paper "Informal landfill contributes to the pollution of microplastic in the surrounding environment" published in Environmental Pollution. We commented on the groundwater sampling procedure that affect the calculated concentrations of microplastics in groundwater. Important information related to the description of sampling wells, informal landfill, and the exact description of sample collection method are missing. In addition, significant data related to the groundwater like water level, flow direction, and velocity have been skipped, which are fundamental in groundwater related studies. There should be a clear diagram of landfill location and sampling wells in the landfill, for appropriate understanding of microplastics (MPs) pollution in surrounding environment of a landfill.

Comment on the paper 'Soil microplastic pollution under different land uses in tropics, southwestern China'.

Research on soil microplastics is currently at an early stage, and there is no widely approved sampling protocol. Even so, any basic research should minimize errors to ensure that they are not amplified in future research. This paper examines some weaknesses of the original research paper 'Soil microplastic pollution under different land uses in tropics, southwestern China' recently published in this journal. The authors neglected to report the equipment used for soil sampling and did not use field blank samples. There is also a soil layer that was incorrectly named. The type and pore size of filter paper used for filtration during pre-analytical soil sample preparation is very important. In this paper the nature of the filter paper used, and its larger pore sizes are questionable by today's scientists. In addition, the authors in the original paper also overlooked reporting the statistical package used for statical analysis and ensuring if all data sets obey normality, homogeneity, and equality before running the one-way ANOVA test. This statistical step is widely considered mandatory, especially in the soil science community. So, this makes it difficult to trust the results documented. Furthermore, in the original paper, the needle and stereo microscope instruments used to sort microplastic-like materials prior to proper analysis are not reliable.

Comment on the paper "Microplastic contamination of an unconfined groundwater aquifer in Victoria, Australia".

This paper was written to comment on a few important problems of an original paper published in this journal. In the original paper, polyamide (PA) ropes, a kind of plastic, were used for groundwater sampling. Also, polycarbonate, another plastic, was also used as a filter paper although their potential contamination was later evaluated. Although the original authors reported that high levels of PA were not found in any of the 21 groundwater samples, it is still necessary to only use equipment(s) made of non-plastic at every step of the method for an accurate and reliable analysis of the presence of microplastic in groundwater. The original authors collected a total of 3 l for each borehole (1 l for each sample), but for an unbiased and reliable analysis of microplastics, bigger volumes of groundwater samples should be collected. Furthermore, the original authors computed the Pearson correlation coefficients between the analyzed plastic types, but omitted the normality test of the data distribution. If the collected data are not normally distributed, then Spearman rank correlation coefficients are a better option. In addition, we found some important misstatements regarding the results of the analysis.