Exposure Concentrations Research Articles

Toxicity and bioconcentration of bisphenol A alternatives in the freshwater pulmonate snail Planorbella pilsbryi.

Bisphenol A (BPA) is an industrial chemical identified as a vertebrate endocrine disruptor. Numerous alternatives have been developed, for which toxicity data are lacking. The present study assessed the toxicity of BPA and its replacement products bisphenol F (BPF), bisphenol S (BPS), and bisphenol AF (BPAF) in freshwater snail (Planorbella pilsbryi) embryos and adults. The chronic toxicity of BPA and BPAF was further characterized in 28-day tests with adult snails, followed by 21-day assessments of hatching and survival of embryos produced at the end of the test (F1 generation). In acute tests, BPAF was the most toxic of the substances tested (maximum acceptable toxicant concentration [MATC], 136 µg/L), followed by BPA (MATC, 1404 µg/L), BPF (MATC, 1525 µg/L), and BPS (MATC>8590 µg/L). In the chronic test with BPA, although we observed no significant effects on adult snails up to 479 µg/L, the hatching and survival of juveniles from the F1 generation decreased (MATC, 13 µg/L), and was delayed by 7.5 days, on average. In contrast, we did not observe any decrease in hatching or survival of juveniles from the F1 generation during exposure to BPAF. Effects were observed at concentrations above most reported environmental exposure concentrations, although there was an overlap between exposure and effect concentrations. Given that concentrations of alternative substances are expected to increase, and in the absence of data on potential effects of mixtures, further research is needed.

Sublethal effects of flonicamid on the population growth of the grain aphid Rhopalosiphum padi (L.) (Hemiptera: Aphididae).

Rhopalosiphum padi is an important grain pest, causing severe losses during crop production. As a systemic insecticide, flonicamid can control piercing-sucking pests efficiently. In our study, the lethal effects of flonicamid on the biological traits of R. padi were investigated via a life table approach. Flonicamid is highly efficiently toxic to R. padi, with an LC50 of 9.068 mg L-1. The adult longevity and fecundity of the R. padi F0 generation were markedly reduced under the LC25 and LC50 concentrations of flonicamid exposure. In addition, negative transgenerational effects on R. padi were observed under exposure to lethal concentrations of flonicamid, with noticeable decreases in the reproductive period, adult longevity, total longevity, and total fecundity of the F1 generation under the LC25 concentration of flonicamid. Furthermore, the third nymph stage (N3), preadult stage, duration of the adult pre-reproductive period, duration of the total pre-reproductive period, reproductive period, adult longevity, total longevity, and total fecundity of the F1 generation were significantly lower under treatment with the LC50 concentration of flonicamid. The life table parameters were subsequently analysed, revealing that the intrinsic rate of increase (rm) and the net reproductive rate (R0) were significantly lower but that the finite rate of increase (λ) and the mean generation time (T) were not significantly different under the LC25 and LC50 concentrations of flonicamid. These data are beneficial for grain aphid control and are critical for exploring the role of flonicamid in the integrated management of this key pest.

Association between phthalate exposure and rash eczema disease: based on NHANES 2005-2006.

Phthalates are commonly found in plastic products, personal care products, and food packaging. In recent years, the relationship between phthalates and skin diseases such as eczema has been gaining attention. As endocrine disruptors, phthalates may increase the risk of eczema by affecting the immune system or skin barrier function. This study used a cross-sectional design based on data from the 2005-2006 National Health and Nutrition Examination Survey to assess the association between phthalate exposure and eczema in adults using generalized linear models, restricted cubic spline plots and weighted quantile sum regression. Eczema diagnosis was determined by participants' self-report of whether they had ever been diagnosed with eczema by doctors. Phthalate exposure was assessed by urinary concentrations of phthalates. A total of 1203 subjects, aged 18years and over, were recruited for the study, comprising 627 males and 576 females. We found that females had significantly higher phthalate exposure concentrations than males. There was a significant positive correlation between monoisononyl phthalate (MiNP) and eczema. Mixture analysis similarly found a positive correlation between phthalates and rash eczema, and MiNP was the main contributor. Further sex-stratified analyses showed that this association occurred predominantly in females, while no significant association was found in the male population. Phthalates may have adverse effects on skin health, particularly in women. Future studies should further investigate the mechanisms of this association and focus on other types of phthalates and their effects on skin health.

Health check-up of a freshwater bivalve exposed to lithium.

Lithium (Li) has become essential for energy and digital transitions, especially as a component of rechargeable batteries. Its growing uses worldwide lead to increasing anthropogenic releases of Li into the environment, which is making Li as an emerging contaminant. It is thus critical to evaluate the ecotoxicological impact of Li, which has been poorly studied unlike its human toxicology. The objectives of this work were to assess the potential adverse effects of Li on aquatic ecosystems. Bioaccumulation and potential sublethal effects (at individual and cellular levels) of Li have been investigated in the widespread and ecologically relevant freshwater bivalve Dreissena polymorpha. To tackle these issues, mussels were exposed to several spiking of 40, 100 and 250μg Li L-1 for 28 days to reproduce anthropogenic contamination scenario. Results demonstrated that bivalves significantly accumulated Li in a dose-dependent manner, from 2 to 10μgg-1 dry weight (bioaccumulation factor, BAF≈19Lkg-1). Bioaccumulation of Li reached a steady-state from seven days of exposure and BAF values were constant regardless the exposure concentration indicating a tight regulation of Li body burden. Lithium exposure leads to increased energy demand associated with a higher lactate dehydrogenase activity and the decrease of protein concentrations. The observed weight gain, increased cellular metabolism, decreased apoptosis, induction of antioxidant defenses and cation content modification in D. polymorpha were also reported in previous studies on humans. The observed effects intensified with exposure concentration and duration, which implies an increased risk for aquatic organisms exposed to Li chronic contamination. Overall, the present study provides new knowledge concerning the impact of Li on non-targeted species, which have implications for the environmental risk assessment of Li in freshwater ecosystems. It also open new perspectives for the understanding of Li toxicokinetics and toxicodynamics on freshwater organisms.

Short-term and long-term effects of microplastics and organic UV-filters on the invertebrate model species Daphnia magna.

There is an ongoing debate regarding the role of microplastics (MPs) in enhancing the effects of various chemical compounds, highlighting the need for more detailed analyses. In this study, neonates of the water flea (Daphnia magna) were exposed to polystyrene MPs (PS-MPs; 3µm; exposure concentration, 1.25mg/L), a mixture of seven organic UV-filters (avobenzone, ethylhexyl triazone, homosalate, iscotrizinol, octinoxate, octisalate, and octocrylene; each at a low environmental concentration of 200ng/L), or the combination of both pollutants for 3, 7, or 21days. Results showed that PS-MPs alone decreased the body size of daphnids, while all treatments increased heart rate by the end of the 21-day exposure. On days 3 and 21, both PS-MPs and PS-MPs + UV-filters reduced swimming speed and total distance travelled. Additionally, PS-MPs increased the time of the first egg production, but decreased the egg number in the first production, total egg number, maximum egg number, and total neonate number during the 21-day treatment. Similarly, UV-filters or the combined pollutants increased the time of the first egg production and decreased the total neonate number. All treatments increased multixenobiotic resistance activity on days 3 and 7, while only UV-filters elevated CYP450 activity on day 3. PS-MPs or combined pollutants increased GST activity during early exposure but showed no effect on day 21. CAT activity was also affected by treatments in a time-dependent manner. These findings demonstrate that chronic exposure to PS-MPs and UV-filters, applied individually or in combination at a low environmental concentration, moderately impacts development, heart rate, and swimming activity in D. magna, while significantly altering reproduction and key cellular functions such as membrane transport activity, metabolism, and antioxidant defense. Co-exposure did not reveal a clear pattern of synergism or antagonism, suggesting that joint toxicity risks of these xenobiotics typically emerge at concentrations higher than low environmental levels. Future studies should explore potential interactions more thoroughly and assess transgenerational effects on reproduction and cellular defense pathways.

The impact of mercury exposure on male reproduction: Mechanistic insights.

Mercury is a pervasive environmental toxin with significant negative effects on human health. In occupational settings, incidents such as the Minamata and Niigata disease in Japan and the large-scale methylmercury poisoning in Iraq have highlighted the severe health impacts of mercury exposure. It is widely accepted that all forms of mercury including methylmercury and mercuric chloride have the potential to induce toxic effects in mammals, and there is increasing concern about the impact of environmentally relevant levels of mercury on reproductive functions. This review summarizes current knowledge on the mechanisms of mercury toxicity, focusing specifically on its impact on male reproductive health across species. We searched the literature and found that mercury exposure is associated with testicular degeneration, altered spermatogenesis, and Leydig cell deformation. In addition, mercury can disrupt sperm motility, steroidogenesis and interfere with the hypothalamic-pituitary-gonadal axis by generation of reactive oxygen species, inducing mitochondrial dysfunction, epigenetic changes, and DNA damage. At the molecular level, mercury has been found to dysregulate the expression of key steroidogenic and spermatogenic genes, significantly reducing overall fertility potential. However, specific mechanisms of action remain to be fully elucidated. Similarly, comprehensive data on the potential transgenerational effects of paternal mercury exposure are lacking. In this review, we discuss both animal and human studies, and highlight the need for further research due to lack of standardization and control for variables such as lifestyle, immune system function, and exposure concentrations.

Vaporized Hydogen Peroxide Uptake by Tubing used for Aseptic Fill-Finish Manufacturing of Biopharmaceutical Drug Products.

Aseptic filling of biopharmaceutical products requires a grade A cleanroom environment, preferably ensured by isolators in grade C surroundings. Isolators are decontaminated before the start of filling processes using vaporized hydrogen peroxide (VHP) and filling starts at pre-defined residual VHP levels (e.g., below 0.5ppm) depending on product sensitivity towards VHP oxidation. Manufacturing equipment and consumables, including filling assemblies, are exposed to VHP during or after the decontamination cycle or after line interruptions. We studied the VHP uptake by tubing in a lab-scale model isolator to evaluate the impact of tubing properties including contact material, tubing dimensions, suppliers, and VHP exposure (concentration and exposure time). Quantifying the release of H2O2 from the tubing into solution using an Amplex Red Hydrogen Peroxide Assay, showed that H2O2 concentrations decreased linearly with an increase in wall thickness and increased with higher surface to volume ratio. We further conclude that thermoplastic elastomer and thermoplastic vulcanizate tubing did not show any measurable VHP uptake for the tested conditions, whereas significant VHP uptake occurred in different platinum cured silicone tubing depending on tubing material and supplier. We further verified the results in a GMP manufacturing isolator setting. Based on our findings, we recommend to evaluate VHP uptake of filling tubing used for fill-finish manufacturing in isolators, to reduce the risk of oxidation for active pharmaceutical ingredients or excipients.

Applying quantitative structure-activity relationship (QSAR) models to extend the mixture toxicity prediction of scrubber water.

Marine organisms are constantly exposed to complex chemical mixtures from natural and anthropogenic sources. One source that has raised concerns is the discharge water from ships equipped with exhaust gas cleaning systems, commonly known as scrubbers. During operation, ships with scrubbers discharge large volumes of scrubber water, known to adversely affect marine organisms, into the environment. Scrubber water is highly acidic and contains a complex mixture of contaminants, including metals and polycyclic aromatic hydrocarbons (PAHs), at high concentrations. To assess the effect from these mixtures, critical values for individual mixture components can be determined from ecotoxicological studies and then compared to measured exposure concentrations. However, for several substances identified in scrubber water, for instance many alkylated PAHs, ecotoxicological studies are unavailable, preventing the determination of critical values. In this study, Quantitative Structure-Activity Relationship (QSAR) models have been used to amend and complement experimental data to estimate the mixture toxicity of scrubber water. Our results show that the combined predicted ecotoxicological response of an amended list of 50 substances measured in scrubber water from the substance groups metals (n=10), PAHs (n=16) and their alkylated derivatives (n=24), still underestimates the response observed in whole effluent toxicity tests. This suggests that there are additional substances and/or synergistic effects in the scrubber water mixtures that contribute to the overall toxicity. Thus, to accurately describe the toxicity of scrubber water, measurements and toxicity assessments must extend far beyond the usual suspects of 16 PAHs and a limited selection of metals. Here, QSAR models and advanced chemical screening-based methods are valuable tools for identifying substances of concern.

Associations between ambient benzene and stroke, and the mediating role of accelerated biological aging: Findings from the UK biobank.

Benzene can cause respiratory diseases. However, the associations between benzene and stroke are unclear. A total of 13,116 patients with stroke and 377,120 controls from the UK Biobank were included. The benzene exposure concentrations were matched on the basis of the address information of each participant via a data form from the UK Department for Environment, Food and Rural Affairs. Weighted Cox regression was used to investigate the association between benzene and stroke risk. The polygenic risk score (PRS) was used to observe the joint effects of benzene exposure and genetic factors on stroke risk. We conducted a mediation analysis to investigate the mediating role of accelerated biological aging in this cohort study. After adjusting for covariates, every 1μg/m3 increase in benzene exposure increased the risk of stroke by 70%, which may be mediated by accelerated biological aging. The population with high benzene exposure concentrations and high PRSs had a 44% greater risk of stroke than did those with low benzene exposure concentrations and low PRSs. Benzene exposure and the PRS have joint effects on the risk of stroke. Benzene exposure was associated with stroke risk, possibly through increased biological aging, and the PRS modified this association.

Safety of Mechanically Fibrillated Cellulose Nanofibers (CNFs) by Inhalation Exposure Based on TG412

An investigation into the acute toxicity of mechanically fibrillated cellulose nanofibers (fib-CNFs), with a fiber length ranging from 500 to 600 nm, was conducted in accordance with the OECD TG412 guidelines. In this study, rats were exposed to fib-CNFs via nasal inhalation for 6 h daily over a 28-day period. The highest exposure concentration was set at 35 mg/m3, with intermediate and low concentrations at 7.0 mg/m3 and 1.5 mg/m3, respectively. No significant differences were observed in body weight, hematological parameters, or biochemical profiles between the fib-CNF-exposed groups and the control group. However, the histopathological examination of lung tissue revealed elevated macrophage counts in both the alveolar spaces and lymph nodes, accompanied by a significant increase in lung weight. The most severe effects were observed in the high-concentration group, while the low-concentration group exhibited only mild inflammatory changes. Based on these findings, the no observable adverse effect level (NOAEL) for the acute toxicity of fib-CNFs is estimated to be below 1.5 mg/m3.

Association between occupational exposure to gasoline and anemia: a retrospective cohort study in China

BackgroundAnemia is a major global burden, and occupational gasoline exposure is a common occupational hazard factor. Although previous studies have shown that there is a potential relationship between occupational gasoline exposure and the increase of anemia prevalence, this relationship has not been fully explored. The current cohort study aimed to investigate the association between occupational exposure to gasoline and anemia, and the effect of gasoline concentration on hemoglobin (Hb) levels.MethodsThis retrospective cohort study collected baseline data from 1451 workers, including 605 exposed to gasoline and 846 not exposed to gasoline. Participants were enrolled in 2013–2015, and follow-up in 2019. Anemia was diagnosed according to WHO guidelines on hemoglobin cutoffs to define anemia in individuals and populations. Occupational exposure concentration of gasoline was measured based on the Chinese national standard (GBZ-T300.62-2017). Logistic regression was conducted to analyze the associations of occupational exposure to gasoline and anemia.ResultsThe incidence of anemia among workers exposed to gasoline was significantly higher than that among non-exposed workers (relative risk [RR] = 11.03, 95% confidence interval [CI]: 9.45–12.53). The risks of anemia were significantly higher among participants exposed to gasoline concentrations ≥ 43.20 mg/m³ (RR = 13.92, 95%CI: 12.25–15.28), 18.01–43.19 mg/m³ (RR = 12.93, 95%CI: 11.07–14.51), and 0.01–18.00 mg/m³ (RR = 5.49, 95%CI: 3.96–7.32) compared with the control non-exposed group. The risk of anemia was significantly higher among exposed workers, after adjusting for all confounding factors. There was also a significant negative correlation between gasoline exposure concentration and hemoglobin level.ConclusionsOccupational exposure to gasoline is associated with an increased incidence of anemia, with a positive correlation between occupational gasoline exposure levels and the severity of anemia. The incidence and severity of anemia increase while hemoglobin levels decrease in line with increasing gasoline exposure concentrations. These findings emphasize the importance of assessing anemia in workers exposed to gasoline.

Effects of Environmentally Relevant Concentrations of Roundup on Oxidative-Nitrative Stress, Cellular Apoptosis, Prooxidant-Antioxidant Homeostasis, Renin andCYP1A Expressions in Goldfish: Molecular Mechanisms Underlying Kidney Damage During Roundup Exposure.

Roundup is one of the most widely used glyphosate-based harmful herbicides in the United States as well as globally, which poses a severe risk for terrestrial and aquatic organisms. In order to identify the detrimental effects of Roundup exposure in aquatic organisms, we investigated the environmentally relevant concentrations of Roundup exposure (low dose: 0.5 μg/L and high dose: 5.0 μg/L for 2 weeks) on renin expression, oxidative-nitrative stress biomarkers (e.g., 2,4-dinitrophenol, DNP; and 3-nitrotyrosine protein, NTP), prooxidant-antioxidant enzymes expressions (e.g., superoxide dismutase, SOD; and catalase, CAT), cellular apoptosis, and cytochrome P450 1A (CYP1A) mRNA levels in the kidneys of goldfish (Carassius auratus). Histopathological and in situ TUNEL analyses showed widespread tissue disruption (e.g., bowman's capsule shrinkage, melanin pigment formation, etc.) and induced apoptotic nuclei in the kidneys of goldfish. Immunohistochemical and quantitative real-time PCR (qRT-PCR) analyses showed a significant (p < 0.05) increase in the expression of renin, DNP, NTP, SOD, and CAT, as well as CYP1A mRNA levels in the kidneys of fish exposed to Roundup. These results suggest that environmentally relevant concentrations of Roundup disrupt kidney architecture by inducing oxidative-nitrative stress, cellular apoptosis, and change in osmoregulatory enzymes (i.e., renin) and prooxidant-antioxidant systems in the kidneys of teleost fishes.

Assessing the Efficacy of Pyrolysis-Gas Chromatography-Mass Spectrometry for Nanoplastic and Microplastic Analysis in Human Blood.

Humans are constantly exposed to micro- and nanosized plastics (MNPs); however, there is still limited understanding of their fate within the body, partially due to limitations with current analytical techniques. The current study assessed the appropriateness of pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) analysis for the quantification of a range of polymers in human blood. An extraction protocol that reduced matrix interferences (false positives) of polyethylene (PE) and polyvinyl chloride (PVC) was developed and validated. Extraction recoveries ranged 7-109%, although surface-modified polystyrene (carboxylated) increased nanoparticle recoveries from 17 to 52%. Realistic detection limits were calculated for each polymer, accounting for matrix suppression and extraction recovery. These were up to 20 times higher than nominal detection limits calculated with Milli-Q water. Finally, the method was tested with a pilot study of the Australian population. PE interferences were reduced but still present, and no other polymers were above detection limits. It was concluded that Py-GC-MS is currently not a suitable analysis method for PE and PVC in biological matrices due to the presence of interferences and nonspecific pyrolysis products. Furthermore, while it is plausible to detect some polymers in blood, the estimated exposure concentrations needed are approaching the detection limits of the technique.

It's about time: moving away from statistical analysis of ecotoxicity data.

Environmental risk assessment of chemicals (ERA) relies on single-species laboratory testing to establish the toxic properties of a compound. However, ERA is not concerned with toxicity under laboratory conditions: it needs to assess the impacts of the compound in the real world. Data-driven statistical analyses (e.g., hypothesis testing and interpolation) are the common approaches for analysing toxicity data, but such approaches are the wrong tool for the job at hand. ERA does not need a statistical description of the effects in the toxicity test (at the end of the standardised test duration), it needs to extrapolate from the laboratory test to longer and time-varying exposure. Such extrapolation requires mechanistic process models, providing a simplified representation of the mechanisms underlying toxicity. Any useful model for the toxicity process should explicitly consider both dose (e.g., exposure concentration) and time. In the history of effects analysis for ERA, the factor of time does not get as much attention as the dose, hence common use of the term 'dose-response analysis'. However, this is a historical oversight: time is a crucial factor for understanding toxicity and thereby essential for meaningful extrapolation from laboratory to field. Mechanistic models for ecotoxicity, considering both dose and time, have been around for quite some time and are classified as toxicokinetic-toxicodynamic (TKTD) models. TKTD models are starting to find their way into pesticide ERA in Europe, next to the classical statistical approaches. In this opinion paper, I argue that it is about time to leave statistical analysis of toxicity data behind us. Statistics remains important for ERA's effects assessment, but its role lies in the definition of appropriate 'error models', explaining the deviations between model output and observations, which is essential for parameter estimation, uncertainty quantification, and error propagation. The 'process model', essential for extrapolation, firmly belongs to TKTD modelling.

The risk of short-term microplastic exposure on female reproductive function: A rat model study.

Long-term effects of microplastics (MPs) exposure have been demonstrated to impair reproductive function. However, in real world, the exposure level of MP is not constant and it may vary in different individuals. This study aims to evaluate the impact of short-term exposure to MPs on ovarian and endometrial function in rat models. Serum steroid hormone concentrations and the expression of ovarian steroid hormone receptor were disturbed. We found that as MPs exposure concentration increased, thickness of the endometrial glandular epithelial layer and the number of endometrial glands decreased; the number of primordial follicles decreased, while the numbers of primary and secondary oocytes significantly increased, indicating a potential oocyte overactivation. Although short-term MP exposure appears to not influence embryo implantation and hormone functions, the results of this study highlight the potential of MPs to disrupt reproductive health in women.

Disulfide Compound-Impregnated Paper Substrate-Based Highly Efficient Colorimetric Gas Sensor for Detection of Volatile Sulfur Compounds in Noninvasive Breath Analysis.

Volatile sulfur compounds (VSCs) are prevalent human biogases detectable in individuals with periodontal disease; therefore, measuring VSC gases in human breath can yield significant, noninvasive diagnostic information indicative of such diseases. In this study, we developed a gas sensor with selective and enhanced sensing capabilities for VSCs methyl mercaptan and hydrogen sulfide. This sensor comprises a cellulose paper substrate impregnated with 2,2'-dithiobis(5-nitropyridine) and sodium acetate. Upon exposure to VSC gases, the initially white sensor element was reversibly changed to yellow. A peak in the diffused reflectance spectrum was noted at 420 nm, establishing a linear relationship between the Kubelka-Munk (K-M) values at 420 nm and the VSC exposure concentration. The sensor demonstrated high sensitivity to methyl mercaptan and hydrogen sulfide with detection limits of 45 and 7.1 ppb in a 1 L volume, respectively. Furthermore, colorimetric analysis of the sensor element images indicated a negative correlation between the K-M value at 420 nm and the B/R value, enabling the calculation of VSC concentration based on the sensor's color change. The cost-effective paper-based sensor simplifies implementation in clinical applications and provides an assay ideally suited for point-of-care.

Transcriptional Pathways Predisposing to Cancer Oxidative Stress Sensitivity and Resistance Are Shared Between Hydrogen Peroxide and Cold Gas Plasma but Not Hypochlorous Acid.

Oxidative stress is universal to all cell types, including cancer. It is elicited by a surplus of reactive oxygen species (ROS) or a reduced cellular ability to defend against those. At low levels (oxidative eustress), this induces altered cellular signaling, while at higher levels (oxidative distress), cellular toxicity and non-specific redox signaling become apparent. While oxidation-induced cell death is a hallmark of many cancer therapies, including ROS-producing radiotherapy, some chemotherapies and targeted therapies, photodynamic therapy, and recently emerging physical modalities such as medical gas plasma (a multi-ROS generating technology), less is known about the transcriptional profiles predisposing cancer cells to oxidative demise. In particular, which genes are associated with resistance or sensitivity to ROS overload and subsequent toxicity has not been systematically investigated. Moreover, it is unclear if there are differences between oxidant types, such as hydrogen peroxide and hypochlorous acid. To this end, we here employed 35 cell lines of various origins (e.g., adenocarcinoma, melanoma, leukemia, squamous cell carcinoma, and neuroblastoma). We first performed in-house transcriptomic analysis to assess baseline transcriptional profiles. Second, all cell lines were exposed to four different ROS concentrations of either hydrogen peroxide, hypochlorous, or gas plasma exposure. Third, correlation analysis was performed to identify genes associated with (i) oxidative stress sensitivity, (ii) oxidative stress resistance, and (iii) similarities and/or differences between the different oxidative stress inducers. Intriguingly, distinct gene sets were found for all treatments, and there was a striking difference between hydrogen peroxide and hypochlorous acid, suggesting different modes of action of both oxidants.

Antimicrobial Activity of UV-Activated and Cysteamine-Grafted Polymer Foils Against Bacteria and Algae.

Surface modification of various polymer foils was achieved by UV activation and chemical grafting with cysteamine to improve surface properties and antimicrobial efficacy. UVC activation at 254 nm led to changes in surface wettability and charge density, which allowed the introduction of amino and thiol functional groups by cysteamine grafting. X-ray photoelectron spectroscopy (XPS) confirmed increased nitrogen and sulfur content on the modified surfaces. SEM analysis revealed that UV activation and cysteamine grafting resulted in distinct surface roughness and texturing, which are expected to enhance microbial interactions. Antimicrobial tests showed increased resistance to algal growth (inhibition test) and bacterial colonization (drop plate method), with significant improvement observed for polyethylene terephthalate (PET) and polyetheretherketone (PEEK) foils. The important factors influencing the efficacy included UV exposure time and cysteamine concentration, with longer exposure and higher concentrations leading to bacterial reduction of up to 45.7% for Escherichia coli and 55.6% for Staphylococcus epidermidis. These findings highlight the potential of combining UV activation and cysteamine grafting as an effective method for developing polymeric materials with enhanced antimicrobial function, offering applications in industries such as healthcare and packaging.

Assessment of the Impact of Monocrotophos on the Haematological and Histological Parameters of the Freshwater Fish Labeo rohita (Hamilton, 1822)

This study investigated the acute sublethal toxicity of Monocrotophos on the behavioural, haematological, and histological parameters of the freshwater fish Labeo rohita. Fish exposed to Monocrotophos (10 ppm and 100 ppm) exhibited notable behavioural alterations, including loss of equilibrium, frequent surfacing, heightened mucus secretion, irregular locomotion, and erratic swimming behaviour. The 96-hour LC50 value for L. rohita was determined to be 48.50 ppm. Sub-lethal concentrations (10, 20, 40, and 60 ppm) were employed to assess the effects of acute exposure over a period of 30 days. The increase in Monocrotophos concentrations led to a consistent decrease in total RBC count and haemoglobin levels, although the total WBC count showed a proportional rise with both concentration and length of exposure. Histopathological analysis revealed significant structural damage to the gill and liver tissues in the treated fish relative to the controls. The findings highlight the substantial behavioural and physiological alterations caused by Monocrotophos exposure in L. rohita. In order to reduce the adverse impact of this chemical on aquatic ecosystems, stringent regulation and attentive application are essential.

A brief history of microplastics effect testing: Guidance and prospect.

Numerous reviews have consistently highlighted the shortcomings of studies evaluating the effects of microplastics (MP), with many of the issues identified in 2016 still relevant in 2024. Here, we summarize the current knowledge on MP effect testing, compare guidelines, and provide an overview of risk assessments conducted at both single species and community levels. We discuss standard test materials, MP characteristics, and mechanisms explaining effects. We have observed that the quality of MP effect studies is gradually improving, and knowledge on enhancing these studies is available. Recommendations include data rescaling and alignment for ecological risk assessment, with preference for using environmentally relevant MPs. A step-by-step protocol for creating polydisperse test materials is provided. Most risk assessments indicate that concentrations observed in ecosystems globally exceed the effect thresholds measured in the laboratory. However, using a higher-tier approach, no risks are expected for freshwater benthic communities at current MP exposure concentrations. Evidence on the mechanisms behind adverse effects is growing; however, more well-designed experiments are needed. A potential solution might involve comparing natural particles with MPs that are as similar in dimensions as possible, providing insight into the mechanisms of food dilution where volume is a critical determinant of toxicity.