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Toluene is a volatile organic solvent found in gasoline. Exposure occurs mainly through absorption via the pulmonary tract and easily reaches the central nervous system, leading to toxic effects. Toluene toxicity has been described but not well documented. The present work aimed to assess the effects of exposure to toluene in air, the in vivo model Caenorhabditis elegans was evaluated to determine if the nematode could be used to assess the effects of exposure to toluene and the possible Assess mechanisms of solvent toxicity. Worms in first and fourth instar larvae were exposed to toluene at concentrations of 450, 850, 1250, and 1800 ppm for 48 and 24 hours, respectively, in a laboratory-developed steam chamber. We observed an increase in worm mortality and significant developmental delays that were concentration dependent. An increased incidence of apoptotic events was detected in treated germ cells, consistent with the observed reduction in reproductive capacity. Furthermore, toluene promoted significant behavioral changes affecting swimming locomotion and radial locomotion associated with changes in fluorescence intensity and morphology of GABAergic and cholinergic neurons. We conclude that toluene exposure was toxic to C. elegans, with effects mediated by the induction of apoptosis and neuronal damage.
Organic solvents refer to a group of chemical substances that are widely used in industrial processes and whose main characteristics are high volatility and fat solubility. Since their first use, these solvents have been linked to promoting various work-related health problems such as hearing loss, cognitive impairment and central nervous system (CNS) damage (Carlini et al., 1988; Thetkathuek et al., 2015). . Currently, we are increasingly surrounded by an environment filled with various types of environmental pollutants, including complex mixtures of gases and particulate matter (Helmig et al., 2014; Losacco and Perillo, 2018).
Pollutants come from a variety of different sources, including industrial processes, agriculture, construction and the burning of fossil fuels (Almaraz et al., 2018; Buczynska et al., 2009; Jirik et al., 2017; Kuzmichev and Loboyko, 2016). . Gasoline production and combustion produces thousands of volatile aromatic molecules that have a strong impact on human health and are potentially carcinogenic (Dehghani et al., 2018).
Gasoline consists of many solvents, mainly aromatic hydrocarbons such as toluene. Toluene is an organic solvent found in many industrial and commercial products such as gasoline and paint thinner. Toluene is very volatile, so its main intake is through the respiratory tract. Surprisingly, its lipid solubility also provides a mechanism for skin absorption (Kang et al., 2005). Due to this lipophilic property, toluene can easily cross biological membranes including the blood-brain barrier and has a negative effect on the CNS (Eisenberg, 2003).
Toluene-induced neurotoxicity is a known effect that has been previously reported. Chronic exposure to the chemical has been responsible for the development of dysfunction or atrophy of the cerebellum and hippocampus (Deleu and Hanssens, 2000; Morata et al., 1993; Morata et al., 1997). Acute toluene exposures have been associated with promoting behavioral changes such as lethargy, drowsiness, memory loss and movement disorders in mammals and invertebrates (Braunscheidel et al., 2017; Davies et al., 2012; Thetkathuek et al., 2015). However, the mechanism of toxicity and the specific neurons affected have not been extensively explored.
Toluene has also been shown to impair reproduction and development in animals. Female rats and their offspring exposed to toluene suffered developmental delays (Gospe et al., 1994). Exposure to toluene is also associated with significant decreases in maternal and offspring body weight and increases in birth defects and early postnatal deaths (Bowen and Hannigan, 2013). Toluene metabolites promote DNA damage and reproductive disorders and are carcinogenic (Murata et al., 1999). Unlike benzene, which has been classified as a genotoxic and carcinogenic substance by the IARC (International Agency for Research on Cancer), toluene is not classified as a carcinogen.
However, they exist ex vivo (Cassini et. .). For these reasons, it is necessary to thoroughly study the effects of toluene to elucidate its mechanism of action. The ability to assess the effects of toluene using the appropriate route of exposure is a permanent limitation. Therefore, a useful experimental model that adheres to the 3Rs guideline in toxicological research and allows for the assessment of toluene toxicity using the appropriate airborne route of exposure , invaluable.
Alternative/complementary models used in toxicity research include the nematode Caenorhabditis elegans. C. elegans is a model with several favorable traits, including a high degree of similarity to mammalian neurotransmission and metabolic pathways and a high degree of genetic homology to mammals (Kaletta and Hengartner, 2006). In addition, the worm has a short life cycle (~21 days), which makes it easier to study long-term effects; it is easy to grow and care for; it is transparent, allowing in vivo observation of fluorescently labeled proteins; and their reproductive and nervous systems have been well studied (Riddle et al., 1997).
Interestingly, the nervous system of C.elegans consists of 302 neurons, which can be labeled with, for example, a green fluorescent protein (GFP) and observed using fluorescence microscopy. As a result, processes of neuronal degeneration induced by toxins such as pesticides, mycotoxins and metals can be observed (González-Hunt et al., 2014; McCarthy et al., 2004; Moyson et al., 2018; Wang and Xing, 2008; Xu et al ., 2017). Worms in particular have neurons that signal internal and environmental CO levels.2(BAG and AFD neurons) (Bretscher et al., 2011) and others sensitive to the presence of O2(URX, AQR and PQR neurons) (Carrillo et al., 2013) responsible for signaling the need for gas exchange. Nematodes do not have a respiratory system, but exchange gases with the environment by diffusing through tissues or pores in their cuticle (Atkinson, 1980), and some studies have shown that worms can respond to volatile organic compounds (VOCs) (Bargmann et al., 1993; Sengupta et al., 1993).
With the above considerations in mind, we assessed the effects of exposure to airborne toluene in the C.elegans model and compared the results in other experimental models. This work confirmed the use of this nematode to study the effects of exposure to toluene. We also examined the neurotoxic effects of toluene and found a possible reproductive toxicity of the chemical that had not previously been demonstrated in vivo.
Reagents and Strains
Liquid toluene (99%) was purchased from Sigma-Aldrich (St. Louis, MO, USA). The strains used in this work were wild-type N2 Bristol, MD701 (bcls39 [lim-7p::ced-1::gfp+lin-15(+)]V, EG1285 (oxls12 [unc-47p::gfp+lin-15 (+)]X and LX929 (vsls48 [unc-17::gfp] obtained from the Caenorhabditis Genetics Center (CGC University of Minnesota, MN, USA).
C.elegans maintenance and synchronization
All strains were maintained in petri dishes containing nematode growth medium (NGM) seeded with Escherichia coli (E. coli) OP50 at 20°C in a
Death from exposure to airborne toluene
Results showed that toluene was highly toxic to worms and that the severity of exposure effects varied in a concentration-dependent manner when worms were exposed at larval stages L1 and L4. As in Figure 2, all toluene concentrations caused a significant reduction in worm survival rates. The 1800 ppm concentration was the deadliest. The data showed that the L4 worms were slightly more resistant to challenge than the L1 worms when exposed to equal concentrations of toluene. the LC50to L1
Humans are currently exposed to various toxic materials in the atmosphere, including, for example, organic solvents present in gasoline. In particular, some types of workers are occupationally exposed to these solvents, and studies have highlighted the toxic effects of these aromatic compounds, which produce a variety of symptoms ranging from neurological abnormalities to genetic alterations (Rekhadevi et al., 2010; Thetkathuek et al . , 2015). ). Our study contributes to the literature
Our work demonstrates that the C.elegans model is appropriate to assess exposure to volatile compounds and that the vapor chamber developed for this study can be used effectively to expose nematodes to volatile compounds. With the tools at our disposal, we characterized effects of toluene that had not previously been reported in the literature. Effects of toluene exposure included reproductive disorders caused by increased apoptosis and neuronal damage to GABAergic and cholinergic neurons.
This study was funded in part by the Coordination for the Improvement of Higher Education Personnel – Brazil (THE LAW) - Financial Code 001. Thanks to the authorsCNPq(universal grants)453963/2014-5,FAPERGS/PqG #18/2551-0000434-0,CNPq/FAPERGS/DECIT/SCTIE-MS/PRONEMNr. 16/2551-0000248-7,FAPERGS/PRONUPEQ#16/2551-0000526-5jUNIPAMPAfor your financing. M.V.S receivedFAPERGS/PRONUPPEQ yTHE LAWScholarship. D.S.A and C.L are beneficiaries of a research grant (PQ2/CNPq). Some tribes were provided by
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Outstanding Toxicity of Isocyanates and Maleic Anhydrides to Caenorhabditis elegans: Multilevel Test for Typical Organic Additives of Biodegradable Plastics
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Regulation of spermatogenic cell apoptosis by pro-apoptotic proteins in mammalian and avian testicular tissues
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In this work, the toxicity and biodistribution of graphene oxide (GO) and oxidized multi-walled carbon nanotubes (MWCNTs) in Caenorhabditis elegans were investigated. Bovine serum albumin (BSA) was chosen as a model protein to assess the influence of protein crown formation on the physicochemical properties, colloidal stability and toxicity of the materials. Biological assays were performed to evaluate the effects of uncoated and albumin-coated materials on survival, oxidative stress, intestinal barrier permeability, growth, reproduction and fertility. Critical changes in topography, surface roughness, and chemistry of GO and MWCNT were observed due to albumin corona formation. These modifications were associated with changes in the materials' colloidal stability and prevention of their aggregation and sedimentation in the nematode test medium. Both GO and MWCNT impaired nematode survival, growth, reproduction and fertility, in addition to increasing oxidative stress and intestinal barrier permeability. But GO was more toxic to C. elegans than MWCNT, especially in long-term tests. Coronaalbumin mitigated 100% of the acute and chronic effects of MWCNT. On the other hand, the negative effects of GO have not been fully mitigated; GO inhibited at the highest concentration tested (10 mg L−1), while crown-coated GO reduced 50 and 100% of fertility and growth, respectively. Confocal Raman spectroscopy images were crucial to identify that GO and MWCNTs, naked and coated with crown albumin, passed through the intestinal barrier of C. elegans and reached their reproductive organs. However, corona-BSA protected nematode target organs from the adverse effects of MWCNT and blocked their translocation to other tissues, while coated GO translocated within the nematodes and impaired crucial organ function. Furthermore, the coated MWCNT was shed after 2 h of refeeding, while the coated GO was still accumulating in the nematode gut. Our results indicate that the different patterns of substance translocation and excretion in C. elegans are related to altered physiological functions of primary and secondary organs. This work contributes to a better understanding of the effects of crown protein on the toxicity of graphene oxide and carbon nanotubes; essential information for biological applications and nanosafety.
Southern Sandy Flathead (Platycephalus bassensis) melanization in the Tamar Estuary, Tasmania, Australia
Pollution, Volume 256, 2020, Item 113452
Recreational anglers in Tasmania have reported dark pigmentation in the normally white fillets of Platycephalus bassensis, a phenomenon known as muscle melanization. Based on histology, it is suggested that eumelanin and pheomelanin are involved in the occurrence of the phenomenon. A macroscopic melanization scoring system was validated using an image analysis technique that quantified the percentage of fillet surface area affected by muscle melanization. The incidence of muscular melanization was more intense in fish inhabiting Enseada do Engenhoso in the Tamar estuary. This indicates that muscle melanization in P. bassensis may be caused by site-specific factors that have yet to be identified. No significant relationships were found between percentage of melanized muscle surface and condition index, age, sex, stage of maturation, fish weight, fish length and size of melanomacrophage centers in liver or spleen. Overall, this study provided important information that will set the direction and focus of future research on melanization of P. bassensis muscles.
Reduced bioavailability of polycyclic aromatic hydrocarbons (PAHs) in sediments affected by coal-fired power plant effluents: assessment by passive ex situ sampling method
Pollution, Volume 256, 2020, Item 113448
The potential hazards of polycyclic aromatic hydrocarbons (PAHs) in sediments from a Japanese bay contaminated by coal-fired power plant effluent were assessed by calculation of toxicity units (TU). UTs calculated from measured total sediment concentrations (Cat) were often greater than or close to 1, indicating a potential toxicity issue for benthic organisms. In contrast, TUs based on freely dissolved pore water concentrations (CBuch), measured by an ex situ passive sampling technique using polyethylene strips, ranged from 0.0007 to 0.005, well below 1, indicating no effect. We also found that soot fractions in the contaminated bay sediments were significantly higher than those of the reference sites. Overall, we conclude that the effluent from coal-fired power plants increases C significantlyatof PAHs in sediments, but also increases the proportion of carbonaceous particles that strongly retain PAHs. As a combined result, the bioavailable concentrations (expressed by interstitial water CBuch) of PAH do not increase as much as Cat. The results of this study indicate that the ecotoxicological risks of PAH contamination from coal-fired power plants should be assessed by directly measuring interstitial water C.Buchinstead of cat.
Using the composite system for synthetic assessment of heavy metal (loid) accumulation in a subtropical basin, China
Pollution, Volume 256, 2020, Item 113396
A composite system with three matrices (water, sediment and rice soil) was developed to determine the potential sources of metals (loides) (Ti, Fe, Co, Ni, Cu, Zn, As, Cd, Pb and U) and their pollution levels in the Synthetically Evaluate Le'an River Basin. The result showed that the observed background values (BV) of the rice soil and sediments in the composite system were obviously higher than those of the upper continental crust (UCC) and the soils of Jiangxi Province, a difference that was particularly pronounced for sediments. The concentrations of Cu, Zn, As, Cd in the system showed high coefficients of variation (CV), and the metals (oids) in the sediment, with the exception of Pb, showed higher values than those in the rice soil. Cd and Cu in the system showed the highest Ef values, likely posing a high risk to organisms and local residents' health. There were significant linear relationships between the site classification index (SRI) for water and that for sediments or clayey soils, showing that the matrices in the system interacted with each other. The results of Principal Component Analysis (PCA) and Absolute Values of Principal Components and Multiple Linear Regression Model (APCS-MLR) showed that the enrichments of Cu, Zn, As, Cu, Pb and U in the system were and have been mainly influenced by mining activities deposited in sediments. Point sources of pollution and non-point sources of pollution such as mining activities contributed most of the anthropogenic (dull) metals to the sediments. The results of the SRI and Hierarchical Cluster Analysis (HCA) visually indicated that the heavy contamination S5, S8, S9, S10, S11 and S12 was concentrated and distributed in areas of extensive mining activity, while other moderately contaminated sites were scattered along the main stream . of the river Le'an.
Properties and health risk assessment of polycyclic aromatic hydrocarbons associated with dust in domestic evaporative coolers
Pollution, Volume 256, 2020, Item 113379
This study reports a characterization of polycyclic aromatic hydrocarbons (PAHs) (dust PAHs) associated with dust in residential evaporative cooling and associated health effects. Extensive analyzes showed that PAHs in cabin dust came mainly from pyrogenic sources (vehicle emissions), with average total concentrations ranging from 131 to 429 ngg−1. The distribution pattern of PAHs based on the number of rings showed the following descending order of relative abundance: 4 > 3 > 5 > 6 > 2 rings. The results indicate that the mutagenicity of dust PAHs exceeded their carcinogenicity, but that potential carcinogenic effects remain significant. Mean lifetime cancer risk for different age groups for three pathways based on model 2 (dermal (1.39 × 10−1a 1.91×10−2), inlet (2.13 × 10−3an 8.08×10−3) and inhalation (1.62×10−7a 4.06×10−7)) was 7.4- to 146-fold greater than the values predicted by model 1 (dermal (5.13 × 10−5a 3.03×10−3), inlet (9.34 × 10−5a 1.31×10−3) and inhalation (7.13×10−20a 1.68×10−20)). Therefore, exposure to dusty PAHs in household evaporative coolers poses a high risk, especially for children (under 11 years) (HQ=2.71 × 10−20and 54.8 of the LTCR = 7.13 × 10−20a 1.39×10−1). Strategies to remove such contaminants should be considered to protect people, especially children, from carcinogenic and non-carcinogenic effects when switching from home evaporative coolers to other cooling systems.
Heavy metal accumulation and genotoxic effects in Levantine vole (Microtus guentheri) collected from mining contaminated areas
Pollution, Volume 256, 2020, Item 113378
Heavy metal pollution is a serious environmental problem that is commonly monitored by various agencies. Small wild rodents are ideal biological monitors to show the extent of environmental pollution. The aim of this study was to assess the adverse effects of marble and stone quarrying on the Levantine vole Microtus guentheri, which inhabits some contaminated sites. In this context, inductively coupled plasma mass spectrometry (ICP-MS) was used to determine the distribution of thirteen heavy metals (Fe, Al, Zn, Cu, Cr, Mn, Ni, B, Pb, As, Co, Cd and Hg) ) in organs (skin, bone, muscle, liver and kidney) from biological samples, and the comet assay showed DNA damage in blood lymphocytes for the first time. This study was conducted near the marble and stone quarries in Korkuteli, Antalya-Turkey during the spring, summer, autumn (2017) and winter (2018) seasons. In spring and summer, genetic damage in blood lymphocytes from all contaminated sites (sites 1 to 5) was significantly greater than in controls, while in autumn it was larger in samples from three sites (sites 3 to 5). As for the distribution of heavy metals in the organs, we found deposits of Fe, Al, Zn, Ni, Mn, Cr, Co, As and Pb mainly in the skin with their derivatives, deposits of Cu and Cd in the kidney. , Cu, Cd and B deposits in the liver and As and Pb deposits in the bones. The study shows that certain organs (especially the skin with its derivatives) and blood lymphocytes of the Levantine vole can be used as ideal indicators of heavy metal exposure. Our results indicate that the Korkuteli area may already be threatened by heavy metal contamination.
Personal exposure to particulate matter (PM2.5) by pregnant women during three trimesters in rural Yunnan, China
Pollution, Volume 256, 2020, Item 113055
About particulate matter (PM2.5) exposure in pregnant women in rural China. This study aims to characterize PM exposure2.5among pregnant women in rural China and to examine potential risk factors for personal PM exposure2.5. The data comes from a birth cohort study that included 606 pregnant women in Xuanwei, a county known for its high rate of lung cancer. Personal exposure to PM2.5was measured during each trimester of pregnancy using small hand-held particle monitors. Participants were surveyed using structured questionnaires to obtain information about PM risk factors.2.5Exhibition. Daily exposure to PM2.5in pregnant women the values were between 19.68 and 97.08 μg/m3(Mean = 26.08). PM exposure2.5it was higher in winter and autumn than in other seasons (p<0.05); greater during the day than at night (p<0.001); and higher during cooking time than during the rest of the day (p<0.001). Using a mixed effects model, household solid fuel for cooking (β=1.75, p<0.001), winter and fall (β=2.96, p<0.001), cooking ≥ once a day (β=1.58, p<0.05 ), charcoal heating (β=1.69, p<0.001), secondhand smoke exposure (β=1.59, p<0.001) and community 1 (β=2.39, p<0.001) were identified as risk factors for identified personal PM exposure2.5Pregnant women throughout pregnancy. Indirect effects of seasonal and county factors on personal PM2.5Exposure was mediated by heating, cooking and the use of fuels in the home. Finally PM2.5Levels in Xuanwei exceeded WHO guidelines. Seasonal and urban factors and individual behaviors, such as B. the use of solid fuels for cooking in the home, heating with coal and exposure to passive smoking are associated with increased personal particulate matter exposure.2.5Exposure in pregnant women in rural China.
This article was recommended for acceptance by Dr. Admire Creso Targino.
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