Increasing Duration Of Exposure Research Articles

Combined environmental relevant exposure to perfluorooctanoic acid and zinc sulfate enhances apoptosis through binding with endogenous antioxidants in Daphnia magna

Perfluorooctanoic acid (PFOA) is a long-chain legacy congener of the per- and polyfluoroalkyl substances (PFAS) family, notorious as a "forever chemical" owing to its environmental persistence and toxic nature. Essential elements such as zinc (Zn) can cause toxic effects when they change their metal speciation and become bioavailable, such as zinc sulphate (ZnSO4). Combined toxicity assessment is a realistic approach and a challenging task to evaluate chemical interactions and associated risks. Therefore, the present study aims to elucidate the acute mixture toxicity (12–48 hours) of PFOA and ZnSO4 in Daphnia magna at environment-relevant concentrations (ERCs, low dose: PFOA 10 μg/L ZnSO4 20 μg/L; high dose: PFOA 20 μg/L ZnSO4 50 μg/L) in terms of developmental impact, apoptosis induction, and interaction with major endogenous antioxidants. Our results showed that deformity rates significantly increased (p < 0.05) with increasing exposure duration and exposure concentrations, compared to the control group. Further, lack of antenna, tale degeneration, and carapace alterations were the most commonly observed deformities following combined exposure to PFOA and ZnSO4, and these malformations were particularly pronounced after 48 h of exposure. Acridine orange (AO) staining was employed to examine apoptosis in D. magna, and apoptotic cells in terms of bright green fluorescence were detected in the abdominal claw carapace, heart, and post-abdominal area following exposure to a high dose of PFOA and ZnSO4. The molecular docking results revealed that both PFOA and ZnSO4 showed strong binding affinities with endogenous antioxidants CAT and GST, where PFOA was more strongly bound with CAT and GST with higher docking scores of -9.59 Kcal/mol and -7.49 Kcal/mol than those with ZnSO4 (-6.70 Kcal/mol and -6.55 Kcal/mol, respectively). In conclusion, the mixture exposure to PFOA and ZnSO4 at the environmental level induce developmental impacts and apoptosis through binding with major endogenous antioxidants in D. magna.

The exploitation of local electric field generated by oxygen vacancies on BiOIO3 nano-antibacterial agents for enhanced photocatalytic sterilisation

Methicillin-resistant Staphylococcus aureus (MRSA) is a typical Gram-positive foodborne pathogen, and its infection has been reported since its discovery. Photocatalysis has emerged as a safe and efficient new sterilization method in clinical and food sectors. In this study, we developed an oxygen vacancy-rich BiOIO3 nano-antibacterial agent using a hydrothermal method, which was successfully synthesized and confirmed through various characterization techniques. Notably, the BiOIO3 nano-antibacterial agent exhibits almost complete inactivation of 107 CFU/mL MRSA within 2 h under visible light irradiation. Furthermore, with increasing exposure duration to irradiation, gradual shrinkage and disintegration of the MRSA cell membrane were observed along with inhibition of the intracellular enzyme activity. Haemolysis tests were performed to prove the biological safety of the agent. Mechanistic investigations revealed that surface oxygen vacancies of BiOIO3 facilitated adsorption binding of water and oxygen within a local electric field promoting reactive oxygen species (ROS) generation. This leads to the rapid accumulation of ROS, which attacks the cell membrane causing significant damage, disrupting normal physiological metabolism of the bacteria, and ultimately killing MRSA. The present study is expected to provide a favourable solution for developing novel efficient and green nano-antibacterial agents through surface modifications.

Alterations and associations between lung microbiota and metabolite profiles in silica-induced lung injury

Silicosis, caused by silica exposure, is the most widespread and deadliest occupational disease. However, effective treatments are lacking. Therefore, it is crucial to elucidate the mechanisms and targets involved in the development of silicosis. We investigated the basic processes of silicosis development and onset at different exposure durations (2 or 4 weeks) using various techniques such as histopathology, immunohistochemistry, Enzyme linked immunosorbent assay(ELISA),16 S rRNA, and untargeted metabolomics.These results indicate that exposure to silica leads to progressive damage to lung tissue with significant deterioration observed over time. Time-dependent cytokines such as the IL-4, IL-13, and IL-6 are detected in lung lavage fluid, the model group consistently exhibited elevated levels of these cytokines, indicating a persistent and worsening inflammatory response in the lungs. Meanwhile, HE and Masson results show that 4-week exposure to silica causes more obvious lung injury and pulmonary fibrosis. Besides, the model group consistently exhibited a distinct lung bacterial population, known as the Lachnospiraceae_NK4A136_group, regardless of exposure duration. However, with increasing exposure duration, specific temporal changes were observed in lung bacterial populations, including Haliangium, Allobaculum, and Sandaracinus (at 4 weeks; p < 0.05). Furthermore, our study revealed a strong correlation between the mechanism of silica-induced lung injury and three factors: oxidative stress, impaired lipid metabolism, and imbalanced amino acid metabolism. We observed a close correlation between cytokine levels, changes in lung microbiota, and metabolic disturbances during various exposure periods. These findings propose that a possible mechanism of silica-induced lung injury involves the interplay of cytokines, lung microbiota, and metabolites.

Spectroscopic probing of ultraviolet-induced degradation in elastomeric polyurea

Aromatic polyurea has garnered assiduous research due to its excellent impact, shock, abrasion, moisture, and chemical resistance properties. Polyurea can be used in protective coating and impact mitigation applications but is inevitably exposed to harsh deployment conditions such as extended ultraviolet (UV) radiation. Fourier Transform Infrared (FTIR) spectroscopy, Terahertz-time domain spectroscopy (THz-TDS), and Excitation-Emission Matrix spectroscopy (EEMS) deciphered the effects of UV radiation on radiated polyurea samples under ambient and nitrogen-rich conditions. Samples were radiated continuously for up to 15 weeks in increments of 3 weeks. Comprehensive FTIR analyses revealed a monotonic increase in disordered hydrogen bonding as a function of exposure duration in an ambient environment. Otherwise, marginal changes were observed in UV-radiated samples under nitrogen. The hydrogen bond length exhibited significant variations in the former compared to their nitrogen atmosphere counterparts. The results infer the nitrogen shielding effect, protecting polyurea from the photodegradation and photo-oxidation observed in samples radiated under the ambient atmosphere. THz-TDS spectra affirmed the FTIR results by probing changes in the complex refractive index. Terahertz spectral peaks associated with torsional vibrations of intermolecular hydrogen bonds in polyurea were notably correlated with increased exposure duration in the ambient atmosphere. Changes in the complex index as a function of exposure duration under nitrogen are minimal. The excitation-emission spectra of polyurea samples reveal a strong fluorescent behavior in 9-week and 12-week ambient-exposed polyurea due to cluster-triggered emission mechanisms. The results synthesized based on three different spectroscopy techniques paint a holistic portrait of the adverse effects of extended ultraviolet radiation of macromolecules deployed in harsh environmental conditions.

Time-dependent hormetic dose responses of skin care product mixtures to Vibrio qinghaiensis sp.-Q67: Appearance and quantification

Hormesis is a widely recognized and extensively studied phenomenon. However, few studies have described the quantitative characteristics of hormesis required for appropriate risk assessment. Although skin care product (SCP) mixtures and their active ingredients can induce the hormesis of Vibrio qinghaiensis sp.-Q67 (Q67), the quantitative characteristics of time-dependent hormetic dose responses in SCPs have not yet been investigated. In this study, 28 SCP mixtures were tested for luminescence toxicity against Q67 after five exposure durations (0.25, 3, 6, 9, and 12 h). With increasing exposure duration, the concentration response curves (CRCs) were classified as constant monotonic nonlinear (S-shaped) for four SCPs, S- to hormetic (J-shaped) for 13 SCPs, and constant J-shaped for 11 SCPs. Of 140 CRCs, 98 were J-shaped. An increased frequency of SCPs inducing hormesis was observed. The toxicity (pEC50) of the SCPs was independent of the exposure duration and product type. The maximum stimulatory effect (Emin) of the 12 SCPs increased with exposure duration. We proposed a modified parameter, the width of inhibition dose zone (WIDZ; EC50/EC10), to depict the width of inhibition dose zone. The WIDZ of S-shaped CRCs were significantly larger than that of J-shaped CRCs. In addition, the characteristic parameters reported in the general literature were analyzed. The good linear relationship between EC50 and the maximum stimulatory effective concentration (ECmin) indicated that toxicity may be transformed into stimulatory effects over exposure durations. The width of stimulation dose zone (WSDZ) and Emin of the seven SCPs had the same increasing trends with increasing exposure duration. The combination of WIDZ with other characteristic parameters (e.g., zero effective concentration point, ECmin, etc.) could better depict hormesis with low-dose stimulation and high-dose inhibition. The quantitative characteristics of the dose-responses of hormesis-inducing SCPs could provide reference basis for the risk assessment of SCP mixtures.

Ethanol Behavioral Responses in Drosophila.

Drosophila melanogaster is a powerful genetic model for investigating the mechanisms underlying ethanol-induced behaviors, metabolism, and preference. Ethanol-induced locomotor activity is especially useful for understanding the mechanisms by which ethanol acutely affects the brain and behavior. Ethanol-induced locomotor activity is characterized by hyperlocomotion and subsequent sedation with increased exposure duration or concentration. Locomotor activity is an efficient, easy, robust, and reproducible behavioral screening tool for identifying underlying genes and neuronal circuits as well as investigating genetic and molecular pathways. We introduce a detailed protocol for performing experiments investigating how volatilized ethanol affects locomotor activity using the fly Group Activity Monitor (flyGrAM). We introduce installation, implementation, data collection, and subsequent data-analysis methods for investigating how volatilized stimuli affect activity. We also introduce a procedure for how to optogenetically probe neuronal activity to identify the neural mechanisms underlying locomotor activity.

Simultaneous effects of aluminum exposure on the homeostasis of essential metal content in rat brain and perturbation of gut microbiota

The theory of the brain-gut axis has confirmed that gut microbiota and metabolites are involved in the progression of neurodegenerative diseases through multiple pathways. However, few studies have highlighted the role of gut microbiota in cognitive impairment induced by aluminum (Al) exposure and its correlations with the homeostasis of essential metal content in the brain. To explore the relationship between alterations in the content of essential metals in the brain and relative abundance changes in gut microbiota induced by Al exposure, the Al, zinc (Zn), copper (Cu), iron (Fe), chromium (Cr), manganese (Mn), and cobalt (Co) content level in the hippocampus, olfactory bulb, and midbrain tissue were measured by inductively coupled plasma mass spectrometry (ICP-MS) methods after Al maltolate was intraperitoneally injected every other day for exposed groups. Then the unsupervised principal coordinates analysis (PCoA) and linear discriminant analysis effect size (LEfSe) were used to analyze the relative abundance of the gut microbiota community and the structure of the gut microbiome. Finally, the correlations between gut microbiota composition and essential metal content in the different exposure groups were explored by using the Pearson correlation coefficient method. Based on the results, we indicated that the content of Al in the hippocampus, olfactory bulb, and midbrain tissue was increased and then decreased with the increasing exposure duration, with peaks occurring between 14 and 30 days. Concomitantly, Al-exposure decreased the Zn, Fe, and Mn levels in these tissues. 16 S rRNA gene sequencing results indicated that significant differences in the intestinal microbial community structure at the phylum, family, and genus levels were found in the Day 90 exposed group compared with the Day 7 exposed group. Ten enriched species in the exposed group were identified as markers at the three levels. Furthermore, ten bacteria at the genus level were identified to have a significantly strong correlation (r = 0.70–0.90) with Fe, Zn, Mn, and Co.

Physiological and biochemical responses of the estuarine pulmonate mud snail, Amphibola crenata, sub-chronically exposed to waterborne cadmium

Physiological and biochemical responses of the pulmonate mud snail, Amphibola crenata, to waterborne cadmium (Cd) were investigated to determine the mechanisms of toxicity and impacts of a 21-d Cd exposure. Mud snails were exposed to nominal Cd concentrations of 0, 0.2, 4 and 8 mg L − 1 and bioaccumulation, whole animal physiological (oxygen consumption, ammonia excretion and oxygen:nitrogen), and tissue level biochemical (catalase activity, lipid peroxidation, glycogen, glucose and protein) endpoints were measured every 7 days. At the two highest Cd exposure concentrations complete mortality was observed over 21-d. In surviving animals, oxygen consumption declined and ammonia excretion rate increased with Cd exposure concentration and duration. The increased ammonia excretion likely reflected enhanced protein metabolism as suggested by a reduced oxygen:nitrogen (O:N). Increasing waterborne Cd concentration and exposure time led to increasing metal accumulation in all tissues. The snail viscera showed the highest Cd accumulation. Both catalase activity and lipid peroxidation in the viscera significantly increased with Cd exposure concentration and time, whereas, the foot muscle and remaining tissues (kidney, mantle, remaining digestive tissues and heart) showed increased catalase activity and lipid peroxidation at higher Cd concentrations (4 and 8 mg L − 1), suggestive of an effect of Cd on oxidative stress. Over the course of 21 days, Cd exposure resulted in significantly lower levels of glycogen in viscera relative to Cd-free controls, reflecting an increased energy demand. Haemolymph glucose rose initially and then fell with increased exposure duration, while haemolymph protein generally exhibited an increased concentration in Cd-exposure groups, reflecting the changes in energy substrates noted for somatic tissues. These results suggest that the physiological and biochemical responses of A. crenata to Cd are conserved relative to other aquatic animals, and were tissue-specific, dose- and time-dependant.

Impacts of polystyrene nanoplastics at the environmentally relevant and sub-lethal concentrations on the oxidative stress, immune responses, and gut microbiota to grass carp (Ctenopharyngodon idella)

Nanoplastics (NPs) are emerging environmental contaminants with alarming ecological and human health concerns due to their unique physicochemical properties. This study elucidates the impacts of environmentally relevant concentrations (ERCs, 300 and 3000 ng/L) and sublethal concentrations (SLCs, 300 and 3000 μg/L) of polystyrene nanoplastics (PS-NPs, size 80 nm) on the intestinal immune response and gut microbiota of grass carp ( Ctenopharyngodon idella ). Exposure to SLCs showed greater accumulation of NPs in gut and gill tissue, and more pronounced gut damage (vacuolization of gut villi) compared to ERCs. SLCs significantly increased ROS levels with increasing exposure duration and exposure concentration (p < 0.05). In addition, SLCs significantly increased the transcription levels of several immune response-related genes such as IL-6 , IL-8 , IL-10 , IL-1β , and TNF-α (p < 0.05). However, the ERC exposure group at 3000 ng/L significantly increased the expression levels of IL-10 and TNF-α , compared to the control group (p < 0.05). Moreover, PS-NPs at both ERCs and SLCs significantly alter grass carp gut microbiota at the phylum and genus levels and disrupts microbial community composition and homeostasis (p < 0.05). At the phylum level, the abundance of Proteobacteria and Verrucomicrobiota was increased after PS-NPs exposure, while that of Spirochaetota and Fusobacteriota decreased. At the genus level, the number of beneficial bacteria decreased and the number of pathogenic bacteria increased. Our findings suggest that PS-NPs at the level of ERCs and SLCs can induce inflammation of the intestine and microbiota imbalance in grass carp. Our findings contribute to a deeper understanding of the gut toxicity of PS-NPs under environmentally relevant conditions in freshwater commercial fish. These experimental results suggest that PS-NPs may indirectly damage grass carp intestinal epithelium by modulating the gut microbiota, thereby damaging the grass carp gut. Hence, this study provides valuable hints on the intestinal barrier structure and functional damage mediated by NPs exposure. • PS-NPs’ effects at environmental & sublethal concentrations on grass carp were investigated. • SLCs induced higher PS-NPs accumulation in the gills and intestines. • SLCs caused higher oxidative stress and structural damage in intestinal tissues. • ERCs and SLCs produced similar changes in the microbiome composition. • Both ERCs and SLCs caused significant gut microbiota dysbiosis and inflammation.

Influence of germicidal ultraviolet radiation UV-C on the quality of Apiaceae spices seeds

BackgroundSpices are susceptible to surface microbial contamination. Countries’ ban on ethylene oxide fumigation due to possible residual toxicity encouraged the usage of irradiation. Surface sterilization with low doses of ultraviolet radiation has been extensively researched as a safe, eco-friendly, and fast route. This study examines the quality of Apiaceae spices for consumption, including anise, fennel, caraway, and cumin, in response to germicidal ultraviolet radiation using a developed sterilization unit.MethodsThe influence of UV-C (254 nm, 10.5 mW/cm2) on the fungal and microbial count, germination percentage, respiration rate, phenolic content, essential oil, and the activity of antioxidant enzymes was investigated at exposure durations of 0–45 min in increments of 5 min. The treated seeds were packed in polyethylene bags in a naturally aerated storage room for 30 days before the inspection.ResultsThe obtained data showed that UV-C stimulated seeds germination and increased respiration rate for all studied types. The 25 min of exposure exhibited the highest significant values compared to the control, considered a good indicator of seed vigor. In addition, UV-C exposure between 20 and 35 min promoted the accumulation of phenolic compounds and increased the oil content as a defense mechanism against radiation. Conversely, higher exposure to UV-C led to a significant reduction in phenolic and oil contents. Furthermore, the exposure to UV-C radiation enhanced the activity of antioxidant enzymes in terms of peroxidase and catalase, which progressively increased with increasing exposure durations, reached their peak at 25–30 min, and subsequently declined with extended exposure time was extended. In a similar pattern, exposure to UV-C radiation increased polyphenol oxidase activity to its highest level at 25 min, owing to the development of antioxidant protective mechanisms against oxidative stress.ConclusionUV-C irradiation in the range of 25–30 min is the most appropriate pretreatment to maintain the vitality of the examined seeds.Graphical

LBMON178 2nd Year Outcomes Of The Open-label Extension Of Chiasma Optimal, A Phase 3 Study Of Oral Octreotide Capsules In Acromegaly

Abstract Background Oral octreotide capsules (OOC) are an approved treatment option in the United States for patients with acromegaly who have previously responded to injectable somatostatin receptor ligands (iSRLs). Safety and efficacy of OOC was demonstrated in the CHIASMA OPTIMAL trial (NCT03252353), showing maintenance of response and a safety profile consistent with iSRLs. Results from the first 48 weeks of the open-label extension (OLE) of this trial suggested that this effect was durable for the long-term. Objective Report efficacy and safety through the second year of the OLE. Methods Eligible patients had the option to enroll in the OLE of CHIASMA OPTIMAL following the double-blind placebo-controlled (DPC) period. Endpoints in the second year of the OLE were exploratory, including: the proportion of patients completing week 96 of the OLE, the proportion of responders entering year 2 who remained responders of those with evaluable data (response defined as average Insulin-like growth factor I [IGF-I] ≤1. 0 × upper limit of normal [ULN] at last 2 visits between weeks 84-96), and changes in IGF-I and growth hormone (GH) from OLE baseline to OLE week 96 in those completing the DPC period on study drug. Results Thirty-two patients from the core period (DPC groups: n=14, placebo; n=18, OOC) entered year 2 of the OLE and 31 (97%) completed. OOC dose at the start of year 2 was 40 mg/d, n=3; 60 mg/d, n=8; and 80 mg/d, n=21. For patients who had non-missing data response rate at 96 weeks was 100% (17/17) for patients who entered year 2 as responders, and 93% (27/29) for patients overall. Mean IGF-I for patients from the OOC group who completed the DPC period on study drug (n=14) was 0.81 × ULN at baseline of OLE and 0.78 × ULN at week 96, (change, −0. 03 × ULN). Mean GH (n=12) was 0.43 ng/mL and 0.44 ng/mL at baseline and week 96, respectively (change, 0. 01 ng/mL). For patients who completed the DPC period on placebo (n=8), mean IGF-I was 1. 05 and 0.77 × ULN at OLE baseline and week 96, respectively (change, −0.28); mean GH (n=5) was 1. 06 and 0.34 ng/mL at OLE baseline and week 96, respectively (change, −0.72 ng/mL). Median exposure to OOC was 2.1 years, with exposure &amp;gt;3 years for 5 patients. Throughout the OLE period, 50% of patients experienced adverse events (AEs), with no serious AEs. One patient discontinued treatment due to an AE (headache). The safety profile was consistent with that reported for OOC; no new patterns were observed with increased exposure. Conclusion Maintenance of biochemical response with OOC was durable up to 96 weeks. The safety profile of OOC was consistent with that of iSRLs. No new safety signals were observed with increased exposure duration. Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

Longer-Term Adverse Effects of Selenate Exposures on Hematological and Serum Biochemical Variables in Air-Breathing Fish Channa punctata (Bloch, 1973) and Non-air Breathing Fish Ctenopharyngodon Idella (Cuvier, 1844): an Integrated Biomarker Response Approach.

To examine the spectrum of selenium toxicity between hardy and less hardy species of the same life stages, short-term and longer-term exposures in juvenile air-breathing fish Channa punctata (Bloch, 1973) and non-air-breathing fish Ctenopharyngodon idella (Cuvier, 1844) were assessed. Acute exposures revealed a greater 96-h median lethal concentration (LC50) for C. punctata (14.67mg/l) compared to C. idella (7.98mg/l). During their chronic exposure, both fishes' hemoglobin content (Hb), red blood cells (RBC), and hematocrit (HCT) markedly decreased (p < 0.05), although their clotting time (CT) significantly increased. At 96h, immune-modulation was observed where total protein and serum globulin levels in both fishes considerably decreased (p < 0.05) compared to the first exposure at 0days, although total glucose, triglyceride, cholesterol, and albumin levels in both fishes significantly increased (p < 0.05) at 30days. The lower cholesterol levels in C. punctata compared to C. idella are suggestive of a disrupted cholesterol transformation pathway. The greater total protein, triglyceride, albumin, and globulin levels in C. punctata compared to C. idella are suggestive of a comparatively robust immune capacity. In essence, selenium toxicity in the wild could manifest as disrupted metabolic pathways and downregulated immune capacity for less hardy species. In general, both fish species displayed significant alterations in their hematological and biochemical responses with increased exposure duration and elevated toxicant concentrations. This comparative investigation could improve the knowledge-spectrum of selenium toxicity in the wild as well as an understanding of secondary stress responses critically evident in hematological and biochemical parameters.

Effect of limestone powder addition on corrosion initiation time of reinforced concrete

This work aimed to evaluate the effects of limestone powder (LP) replacement fraction (8–24 wt%) on chloride diffusion and chloride threshold (Cth) for corrosion initiation. Depassivation of steel was diagnosed by monitoring the self-corrosion potential and corrosion current density using open circuit potential and AC impedance tests, respectively. Corrosion initiation time (Tini) was estimated based on the measured Cth coupled with a dual time-varying diffusion model. The results indicate that the chloride diffusion coefficient decreases with 8 wt% LP addition, though further increase in LP content reverses the trend. With increasing exposure duration, both the surface chloride concentration and diffusion coefficient vary remarkably at first and eventually tend to be stable. As the cover depth decreases from 55 mm to 45 mm, Tini is found to decrease by 30.0%–42.9%. Incorporation of LP appreciably decreases Cth regardless of its replacement fraction, consequently leading to a decreased Tini, despite a low chloride diffusivity can be obtained with appropriate LP addition.

Migration of bisphenol A from epoxy-can malt drink under various storage conditions and evaluation of its health risk

ABSTRACT Bisphenol-A (BPA) is a notable endocrine disrupting chemical and a core raw material utilised in the manufacture of some food contact materials such as epoxy resin and polycarbonate (PC) plastics. The human health risk (HRI) associated with the migration of BPA into malt drinks packaged in epoxy-cans and stored under various conditions was investigated. Solid-phase extraction (SPE) was used to extract BPA, while analysis was performed with a high performance liquid chromatography coupled to an ultraviolet detector (HPLC-UV). The health risk index was used to assess the likelihood of developing chronic non-carcinogenic health risk among consumers of epoxy-can malt drink. Results showed BPA concentrations at 3.98 ± 0.05°C, 25.34 ± 0.70°C and 30.98 ± 0.27°C range from 0.0166 to 0.0300 μg L−1, 0.0188 to 0.0788 μg L−1 and 0.0217 to 0.2131 μg L−1 respectively. BPA levels in the samples did not exceed the European Union limit (50 μg kg−1). Enrichment levels of BPA in samples stored at 30.98 ± 0.27°C were highest, while that at 3.98 ± 0.05°C samples were the least. Initial migration rate of BPA at 3.98 ± 0.05°C and 25.34 ± 0.70°C decreased with increasing exposure duration, and later maintained a mildly constant rate at longer exposure duration. However, at 30.98 ± 0.27°C, BPA migration rates decreased initially with increase in exposure duration, and increased later at prolonged exposure. Although BPA concentrations showed no significant difference (p > 0.05) at the study’s storage conditions, a significant difference (p < 0.05) was observed in BPA migration rates. The computed chronic non-carcinogenic health risk for daily ingestion of malt drink contaminated with BPA by both adults and children was less than one indicating no probable adverse health effect from consumption of the malt drink.

Comparative Bioactivity of Bamboo Leaf Ash and Bularafa Diatomaceous Earth against Maize Weevil (Sitophilus zeamais Motschulsky)

Maize is one of the major staple foods in Sub-Saharan Africa and there is serious loss in maize storage due to insect damage. This study compared the bioactivity of Bamboo Leaf Ash (BLA) and Bularafa Diatomaceous Earth (BDE) against Maize Weevil (Sitophilus zeamais Motschulsky) under laboratory conditions. Insecto®, a commercialized DE was also tested as standard check. Adults of the insects were exposed on maize admixed with the BLA at dose rate of 5,000, 10,000 and 20,000ppm; BDE and insecto® at a dose rate of 1,000ppm, at 28.20C and 82.2% relative humidity. Mortality increased with increasing exposure duration and all treatments showed mortality of more than 80% after 14days post-treatment compared to negative control with 0%.The treatments suppressed F1 progeny. Treated grains have weight loss less than 4%, kennel damage less than 14% and grain germination showed no significant change. The decreasing efficacy of the dusts against this insect is Insecto®&gt; BLA &gt; BDE. BLA and BDE have potential for the management of insect pests of stored grain in Nigeria.

Toxicity of Wildland Fire-Fighting Chemicals in Pulsed Exposures to Rainbow Trout and Fathead Minnows.

Intrusions of fire-fighting chemicals in streams can result from containment and suppression of wildfires and may be harmful to native biota. We investigated the toxicity of seven current-use fire-fighting chemicals to juvenile rainbow trout (Oncorhynchus mykiss) and fathead minnows (Pimephales promelas) by simulating chemical intrusions under variable field conditions to provide insights into the potential damage these chemicals may cause in waterways. In three separate attenuated exsposure assays in which chemical concentration decreased throughout the 96-h exposure period, we variedwater flow rate, water hardness, and initial concentration of test chemical. In an additional series of four pulsed exposure assays in which fish encounter chemical for up to 1 h followed by an observation period in control water, we altered concentration of test chemical, water temperature, duration of chemical exposure, and number of exposures to determine delayed toxicity or recovery. Mortality of rainbow trout was higher across treatments at a warmer temperature and also increased with increasing concentration rate, increasing exposure duration, and sequential exposures across assays. For fathead minnows, mortality increased with increasing concentration of fire retardant and longer exposure durations. Because the ratio of toxic un-ionized ammonia to ionized ammonia is greater with increasing temperature and pH, future studies could investigate the effects of water temperature and pH on native fishes under environmentally relevant concentrations of fire-fighting chemicals. Environ Toxicol Chem 2022;41:1711-1720. Published 2022. This article is a U.S. Government work and is in the public domain in the USA.

Fluoride sensitivity in freshwater snail, Bellamya bengalensis (Lamarck, 1882): An integrative biomarker response assessment of behavioral indices, oxygen consumption, haemocyte and tissue protein levels under environmentally relevant exposure concentrations

There is limited information on fluoride toxicity and risk overview on ecotoxicological risks to aquatic invertebrate populations particularly molluscan taxa. This necessitated the assessment of toxicity responses in the freshwater snail, Bellamya bengalensis exposed to environmentally relevant concentrations of sodium fluoride. Under lethal exposures (150, 200, 250, 300, 400 and 450 mg/l), the median lethal concentrations (LC50) were determined to be 422.36, 347.10, 333.33 and 273.24 mg/l for B. bengalensis at 24, 48, 72 and 96 h respectively. The rate of mortality of the snails was increased significantly with elevated concentrations of the toxicant. The magnitude of toxicity i.e., toxicity factor at different time scale was also higher with increased exposure duration. Altered behavioural changes i.e., crawling movement, tentacle movement, clumping tendency, touch reflex and mucous secretion in exposed snail with elevated concentrations and exposure duration. Similarly, oxygen consumption rate of the treated snail also lowered significantly during 72 and 96 h of exposure. Under 30-day chronic exposures (Control-0.00 mg/L; T1–27.324 mg/L; T2–54.648 mg/L), protein concentrations in gonad and hepatopancreas of exposure groups was significantly lowered. Chronic exposures also revealed lowered haemocytes counts in exposure groups. The potential for loss of coordination, respiratory distress and physiological disruption in organisms exposed to environmentally relevant concentrations of fluoride was demonstrated by this study. The estimation and magnitude of toxicity responses are necessary for a more accurate estimation of ecological risks to molluscan taxa and invertebrate populations under acute and chronic fluoride exposures in the wild.

Pulse-Exposure Toxicity of Ammonia and Propoxur to the Tropical Copepod Acartia sinjiensis.

Toxicity risk assessments of short-term discharges of contaminated waters to the aquatic environment have shown that receptor organisms can tolerate higher pulse-exposure than continuous-exposure concentrations of some contaminants. However, these observations are influenced by the mode of toxicity of the contaminants present and the concentration-time profile of the exposure. For common metal contaminants, the time-weighted average concentration (TAC) of the exposure has been useful for predicting risk of toxicity to multiple species, including the tropical, euryhaline copepod Acartia sinjiensis. To increase our understanding of the application and limitations of the TAC approach, the present study examined how varied pulse-exposure durations affect the toxicity of fast-acting contaminants, ammonia, and the common pesticide propoxur to this copepod species. Copepod larvae were exposed under continuous-exposure conditions (all life stages from eggs to nauplii to copepodites exposed) and as 6- and 18-h pulse exposures applied during the most sensitive life stage only (24-h-old nauplii) within 78-h tests. Larval development ratio and population size were assessed as test endpoints. Generally, increased exposure duration resulted in increased toxicity. Trends observed for ammonia and propoxur were slightly different for larval development and population size. Larvae tolerated greater concentrations of contaminants in a 6-h pulse (higher 10% effect concentration) than in an 18-h pulse, or a continuous 78-h exposure, whereas toxicity responses converged for the 18- and 78-h exposures. Continuous toxicity thresholds were always protective of pulse exposures, providing a conservative toxicity threshold for all durations of pulse exposures. Although generalizations for predictions of risk based on TACs are frequently effective for common metal contaminants, the TAC approach was not effective for ammonia and propoxur. Environ Toxicol Chem 2022;41:208-218. © 2021 SETAC.

Flexural behavior and modelling of FRP-bar reinforced seawater sea sand concrete beams exposed to subtropical coastal environment

This paper presents long-term flexural behavior of FRP-bar reinforced concrete beams exposed to subtropical coastal environment. Four-point bending tests were conducted and the effects of exposure duration, concrete type, and FRP-bar type were investigated. The load-deflection response of such beams features a nonlinear hardening following the linear ascending. Generally, their ultimate load-carrying capacity was reduced with the increasing exposure duration and further reduced when the seawater and sea sands were used, the BFRP-bar reinforced beams produced higher capacity than the GFRP-bar reinforced ones. For a design-oriented purpose, current American and Chinese codes were modified to determine their load-carrying and deformation capacities at both ultimate and serviceability limit states; for an analysis-oriented purpose, the finite element model has been established and justified to capture their failure modes and stress-strain response.

Is Ignorance Bliss? Examining the Effect of News Media Exposure on Anxiety and Depression During the COVID-19 Pandemic.

There has been a widespread increase in affective disorders after the emergence of the COVID-19 pandemic. In the current study, we investigated the effects of exposure to and perceived accuracy of news media and demographic characteristics on anxiety and depressive symptoms. We conducted an online survey of US adults (N = 480) using hierarchical linear regression models to understand the predictive roles of duration and frequency of news media exposure, as well as the perceived accuracy of COVID-19 portrayal by the news media, on anxiety and depression. Increased exposure duration predicted greater anxiety, and decreased frequency of exposure and perceived overreaction in the news media coverage of COVID-19 were linked to greater anxiety and depression. Perceived accuracy moderated the relationship of exposure frequency to both affective outcomes. Accordingly, our data support the importance of adequate levels of accurate and trusted information to help mitigate the overall mental health burden of the pandemic.