Günther Gehlen

Plastic waste is one of the main causes of the deterioration of freshwater ecosystems. Once in the environment, microplastics (MPs) have harmful effects on living organisms and pose risks to human health. This study used an integrated approach to assess the presence of microplastics in surface water and sediment samples from three sites along the Sinos River in the State of Rio Grande do Sul, Brazil. Scanning Electron Microscopy (SEM) and Energy-Dispersive Spectroscopy (EDS) were employed for characterization, and a Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model was proposed to understand atmospheric influences. Microplastics were found in all samples and sites, including the river's source. Fibers were predominant, and particle sizes ranged from 67 µm to 4.2 mm. A total of 109 particles were recovered from the water samples (12±4 L-1 particles), and 21 from the sediment samples (2±2 100 g-1 particles). SEM analysis revealed surface cracking, and EDS confirmed the prevalence of carbon and oxygen in the particles. Based on the atmospheric model, the trajectories of air masses prior to sampling at the highest site demonstrate that MPs can be transported from other locations. Our study reports microplastic contamination in Caraá for the first time, provides insights for future studies on the atmospheric transport and deposition of microplastics in countryside regions, and highlights the urgent need to include these pollutants in environmental quality assessments of this important hydrographic basin.

Titanium implants can release ions that damage cells. Anodization creates a protective oxide layer, but conventional acid methods raise environmental and safety concerns. This study evaluates in vitro cytotoxicity and osseointegration with the Psidium guajava aqueous leaf extract (PgE) as an alternative anodization electrolyte for titanium plates. For this purpose, 1‐cm ² titanium plates were anodized with H ₃ PO ₄ , a combination of H ₃ PO ₄ +HF or PgE, and each group was assessed for its impact on cell viability, adhesion, and proliferation in osteosarcoma (Saos‐2) and fibroblast (NIH‐3T3) cells. The plate surfaces were characterized by energy‐dispersive X‐ray spectroscopy (EDS), X‐ray diffraction (PXRD), and contact angle measurements using the sessile drop method, demonstrating greater hydrophilicity in plates anodized with PgE. Cytotoxicity was assessed using both indirect assays (extraction media) and direct assays, where cells were seeded directly onto titanium plates; cell viability was determined by MTT and NRU assays after 24 and 96 h. Osseointegration was analyzed by counting nuclei through DAPI staining and adhesion using scanning electron microscopy. In indirect assays, all samples showed no significant difference compared to the control (ANOVA/Tukey’s; p < 0.05), while direct assays demonstrated an average increase in cell viability on all anodized plates. The number of cell nuclei increased on H ₃ PO ₄ and PgE plates in both cell lines compared to pure titanium. SEM analysis revealed improved cell morphology and adhesion on surfaces anodized with H ₃ PO ₄ or PgE, whereas cells on H ₃ PO ₄ +HF appeared thinner and less spread, suggesting impaired cellular anchorage. The results show that using PgE as an anodization electrolyte for titanium plates caused no cytotoxicity and enhanced cell proliferation and adhesion, outperforming conventional H ₃ PO ₄ +HF electrolyte. This makes it a promising and sustainable alternative aligned with green chemistry principles.

This study aimed to report the effects of chronic exposure of zebrafish exposed to environmentally relevant concentrations of 0.5, 2.4, and 5.0 mg L⁻¹ iron (Fe) and 0.2, 0.4, and 2.0 mg L⁻¹ aluminum (Al). We also evaluated the reversal and generational transposition (F1) of possible histopathological, behavioral, and genotoxic changes in the species. Locomotion changes that may have been caused by the increase in the number of apoptotic cells and in the telencephalic mitochondrial activity were observed especially after the 30 days exposure to Al and persisted after recovery (30 days). We also observed histopathological changes, such as an increase in the number of intestinal goblet cells, even after the recovery period in these animals. Our results also showed that the Fe concentrations used were insufficient to cause genotoxicity, behavioral and intestinal epithelium changes. The adult offspring (F1) of animals exposed to Al showed changes in locomotion and in the amount of goblet cells, demonstrating that even in low concentrations this pollutant can harm subsequent generations in the aquatic biota. Animals demonstrate, in general, greater tolerance to Fe which may be related to the physiological demand of this metal by the body. Even so, all concentrations of both metals that caused some change in the species represent Brazilian environmental occurrences or Brazilian legislation. It highlights the need for updating the guidelines and constant monitoring of aquatic environments, since even in the face of a hypothetical decontamination of the environment, some changes could persist and affect different trophic levels.

The PT-31 molecule, a potential antipsychotic, has demonstrated promising results when orally administrated to in vivo models. A recent study suggested the genotoxic and mutagenic potential of PT-31 after acute treatment by intraperitoneal route. This study aimed to evaluate PT-31 potential of inducing genotoxic or mutagenic damage after acute oral administration. For that, adult males and females Balb/C mice were treated acutely by oral administration with vehicle or PT-31 in three different doses (10, 20, and 40 mg kg-1). After 24 hours from PT-31 administration, animals were euthanized for performing the comet and micronucleus assays. None of the tested groups of PT-31 presented a significant increase in damage index and MN frequency. However, they presented the following tendency on damage index: females presented a tendency at 40 mg kg-1 and males at 20 mg kg-1. Regarding the MN assay, male mice at the highest dose of 40 mg kg-1 presented a tendency of increased MN frequency. Also, there was a significant increase in PCE/NCE ratio in male mice. Results suggest that the male mice group presented higher susceptibility to damage. The tendency of increased damage to DNA and MN frequency suggests that the molecule PT-31 may induce reparable damage to DNA, and these DNA strand repairs may have originated from the MN. However, significant genotoxic and mutagenic effects were not observed. This study reinforces the atypicality of the molecule as much as its safety by oral route administration.

Titanium dioxide nanoparticles (TiO₂-NPs) are among the most used nanomaterials worldwide, but studies evaluating its genotoxicity and histopathological effects are scarce, dealing with short exposure times and low concentrations for human use. The aim was to evaluate TiO₂-NPs genotoxicity and histological alterations in the intestine and liver of zebrafish after exposure to human consumption compatible concentrations. Fishes were acutely (96 hours) and chronically (30 days) exposed to 5.0, 20 and 40 mg L^-1 of TiO₂-NPs and later euthanized for organ and blood analysis through histological procedures and the micronucleus test, respectively. An increase in the thickness of intestinal villi was observed after acute and chronic exposure in the higher concentrations. The liver showed an increase in vacuolated hepatocytes after both exposures, besides an increase in hepatocytes with peripheral nucleus. Genotoxicity was only observed after chronic exposure, demonstrated by the increase in micronucleus and cell buddings. These findings indicate that TiO₂-NPs cause histopathological damage even in acute exposures, as the intestine serves as a barrier for NPs and the liver is an organ that accumulates Ti. Genotoxicity was possibly mediated by reactive oxygen species through chronic inflammation, leading to tissue damage and carcinogenesis in longer exposures that represents human exposure time.

The analysis of metal concentrations in bird feathers and genotoxicity tests are tools used to evaluate anthropogenic impacts on ecosystems. We investigated the response of birds, used as bioindicators, to disturbances observed in three areas with distinctive environmental characteristics (natural, agricultural, and urban) in southern Brazil. For this purpose, we quantified metals (Mn, Cu, Cr, and Zn) in feathers and determined the number of micronuclei (MN) and other nuclear abnormalities (NA) in 108 birds from 25 species and 17 families captured in the study area. No significant differences was found in the metal concentrations and the number of MN and NA between the sampling areas. Zn and Cu concentrations were significantly higher in insectivorous than those in omnivorous birds. The Zn concentration was significantly different between some species, and the Cu concentration was significantly higher in juveniles than that in adults. The best generalized linear models showed that omnivorous birds had more MN and NA and that juveniles and birds with better body condition index had increased NA numbers. This study demonstrates that the analyzed variables contribute in different ways to the result of each biomarker, mainly due to particular ecological and physiological characteristics of each species. We conclude that wild birds have the potential to be used as environmental bioindicators in the study area, but future studies should focus on one or a few species whose ecological and physiological habits are well known.

The aim of this study was to monitor the water quality of Luiz Rau stream, through physicochemical parameters, environmental characteristics of the site, and genotoxicity test in Allium cepa. Four water samples from Luiz Rau stream were collected once a week for one month and some physicochemical parameters were verified. The environmental characteristics were performed by the Quick Assessment Protocol (QAP) and evaluated at the sampling site. For the genotoxicity assay, the Allium cepa test was utilized. In relation to the water physicochemical parameters, low levels of dissolved oxygen (DO) and high levels of ammonia, and phosphorus were obtained, which demonstrates the poor quality of the stream. The QAP results identified the stream as impacted. The mitotic index parameter was altered in the seed exposed to raw water samples in the third and fourth sample collection, demonstrating cell cycle reduction and proliferation respectively; witch can be associated with the presence of contaminated effluents in the water. In relation to the genotoxicity, the micronuclei were increased in seeds exposed to four raw samples in comparison to the control group. Therefore, the results obtained can characterize the Luiz Rau stream as impacted, mostly by anthropic actions, corroborating with other publications.