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Developmental alterations, teratogenic effects, and oxidative disruption induced by ibuprofen, aluminum, and their binary mixture on Danio rerio Texte intégral
2021
Sánchez-Aceves, Livier M | Pérez-Alvarez, Itzayana | Gómez-Oliván, Leobardo Manuel | Islas-Flores, Hariz | Barceló, Damià
Developmental alterations, teratogenic effects, and oxidative disruption induced by ibuprofen, aluminum, and their binary mixture on Danio rerio Texte intégral
2021
Sánchez-Aceves, Livier M | Pérez-Alvarez, Itzayana | Gómez-Oliván, Leobardo Manuel | Islas-Flores, Hariz | Barceló, Damià
Several studies highlighted the ubiquitous presence of ibuprofen and aluminum in the aquatic environment around the world and demonstrated their potential to induce embryotoxic and teratogenic defects on aquatic species individually. Although studies that evaluate developmental alterations induced by mixtures of these pollutants are scarce; and, since environmental contamination presented in the form of a mixture of toxicants with different chemical properties and toxicity mechanisms capable of generating interactions; the objective of this study was to evaluate the developmental defects, teratogenic alterations, and oxidative stress induced by individual forms and the mixture of ibuprofen (IBU) and aluminum (Al) on zebrafish embryos. Oocytes exposed to environmentally relevant concentrations of IBU (0.1–20 μg L-1) and Al (0.01–8 mg L-1) and one binary mixture. The LC50 and EC50 were obtained to calculate the teratogenic index (TI). The IBU LC50, EC50, and TI were 8.06 μg L-1, 2.85 μg L-1 and 2.82. In contrast, Al LC50 was 5.0 mg L-1with an EC50 of 3.58 mg L-1 and TI of 1.39. The main alterations observed for individual compounds were hatching alterations, head malformation, skeletal deformities, hypopigmentation, pericardial edema, and heart rate impairment. The mixture also showed significant delays to embryonic development. Moreover, oxidative stress biomarkers of cellular oxidation and antioxidant defenses at 72 and 96 hpf significantly increased. Results show that environmentally relevant concentrations of ibuprofen (IBU), aluminum (Al), and their mixture promote a series of developmental defects, teratogenic effects, and oxidative disruption on D. rerio embryos, and the interaction of both substances altered the response. In conclusion, morphological and biochemical tests are suitable tools for assessing the health risk of aquatic wildlife by exposure to individual and mixed pollutants in freshwater bodies.
Afficher plus [+] Moins [-]Developmental alterations, teratogenic effects, and oxidative disruption induced by ibuprofen, aluminum, and their binary mixture on Danio rerio Texte intégral
2021
Sánchez-Aceves, Livier M. | Pérez-Alvarez, Itzayana | Gómez-Oliván, Leobardo Manuel | Islas-Flores, Hariz | Barceló, Damià | Barceló, Damià [0000-0002-8873-0491] | Consejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]
Several studies highlighted the ubiquitous presence of ibuprofen and aluminum in the aquatic environment around the world and demonstrated their potential to induce embryotoxic and teratogenic defects on aquatic species individually. Although studies that evaluate developmental alterations induced by mixtures of these pollutants are scarce; and, since environmental contamination presented in the form of a mixture of toxicants with different chemical properties and toxicity mechanisms capable of generating interactions; the objective of this study was to evaluate the developmental defects, teratogenic alterations, and oxidative stress induced by individual forms and the mixture of ibuprofen (IBU) and aluminum (Al) on zebrafish embryos. Oocytes exposed to environmentally relevant concentrations of IBU (0.1–20 μg L-1) and Al (0.01–8 mg L-1) and one binary mixture. The LC50 and EC50 were obtained to calculate the teratogenic index (TI). The IBU LC50, EC50, and TI were 8.06 μg L-1, 2.85 μg L-1 and 2.82. In contrast, Al LC50 was 5.0 mg L-1with an EC50 of 3.58 mg L-1 and TI of 1.39. The main alterations observed for individual compounds were hatching alterations, head malformation, skeletal deformities, hypopigmentation, pericardial edema, and heart rate impairment. The mixture also showed significant delays to embryonic development. Moreover, oxidative stress biomarkers of cellular oxidation and antioxidant defenses at 72 and 96 hpf significantly increased. Results show that environmentally relevant concentrations of ibuprofen (IBU), aluminum (Al), and their mixture promote a series of developmental defects, teratogenic effects, and oxidative disruption on D. rerio embryos, and the interaction of both substances altered the response. In conclusion, morphological and biochemical tests are suitable tools for assessing the health risk of aquatic wildlife by exposure to individual and mixed pollutants in freshwater bodies. | This study was made possible by financial support from the Consejo Nacional de Ciencia y Tecnología (CONACyT, Project 300727). | Peer reviewed
Afficher plus [+] Moins [-]Developmental toxicity in zebrafish (Danio rerio) exposed to uranium: A comparison with lead, cadmium, and iron Texte intégral
2021
Shankar, Prarthana | Dashner-Titus, Erica J. | Truong, Lisa | Hayward, Kimberly | Hudson, Laurie G. | Tanguay, Robyn L.
Populations of plants and animals, including humans, living in close proximity to abandoned uranium mine sites are vulnerable to uranium exposure through drainage into nearby waterways, soil accumulation, and blowing dust from surface soils. Little is known about how the environmental impact of uranium exposure alters the health of human populations in proximity to mine sites, so we used developmental zebrafish (Danio rerio) to investigate uranium toxicity. Fish are a sensitive target for modeling uranium toxicity, and previous studies report altered reproductive capacity, enhanced DNA damage, and gene expression changes in fish exposed to uranium. In our study, dechorionated zebrafish embryos were exposed to a concentration range of uranyl acetate (UA) from 0 to 3000 μg/L for body burden measurements and developmental toxicity assessments. Uranium was taken up in a concentration-dependent manner by 48 and 120 h post fertilization (hpf)-zebrafish without evidence of bioaccumulation. Exposure to UA was not associated with teratogenic outcomes or 24 hpf behavioral effects, but larvae at 120 hpf exhibited a significant hypoactive photomotor response associated with exposure to 3 μg/L UA which suggested potential neurotoxicity. To our knowledge, this is the first time that uranium has been associated with behavioral effects in an aquatic organism. These results were compared to potential metal co-contaminants using the same exposure paradigm. Similar to uranium exposure, lead, cadmium, and iron significantly altered neurobehavioral outcomes in 120-hpf zebrafish without inducing significant teratogenicity. Our study informs concerns about the potential impacts of developmental exposure to uranium on childhood neurobehavioral outcomes. This work also sets the stage for future, environmentally relevant metal mixture studies. Summary Uranium exposure to developing zebrafish causes hypoactive larval swimming behavior similar to the effect of other commonly occurring metals in uranium mine sites. This is the first time that uranium exposure has been associated with altered neurobehavioral effects in any aquatic organism.
Afficher plus [+] Moins [-]The zebrafish embryotoxicity test (ZET) for nanotoxicity assessment: from morphological to molecular approach Texte intégral
2019
Pereira, Aryelle Canedo | Gomes, Tania | Ferreira Machado, Mônica Rodrigues | Rocha, Thiago Lopes
The zebrafish embryotoxicity test (ZET) for nanotoxicity assessment: from morphological to molecular approach Texte intégral
2019
Pereira, Aryelle Canedo | Gomes, Tania | Ferreira Machado, Mônica Rodrigues | Rocha, Thiago Lopes
Nanotechnology and use of nanomaterials (NMs) improve life quality, economic growth and environmental health. However, the increasing production and use of NMs in commercial products has led to concerns about their potential toxicity on human and environment health, as well as its toxicological classification and regulation. In this context, there is an urgent need to standardize and validate procedures for nanotoxicity testing. Since the zebrafish embryotoxicity test (ZET) has been indicated as a suitable approach for the toxicity assessment of traditional and emergent pollutants, the aim of this review is to summarize the existing literature on embryotoxic and teratogenic effects of NMs on zebrafish. In addition, morphological changes in zebrafish embryos induced by NMs were classified in four reaction models, allowing classification of the mode of action and toxicity of different types of NM. Revised data showed that the interaction and bioaccumulation of NMs on zebrafish embryos were associated to several toxic effects, while the detoxification process was limited. In general, NMs induced delayed hatching, circulatory changes, pigmentation and tegumentary alterations, musculoskeletal disorders and yolk sac alterations on zebrafish embryos. Recommendations for nanotoxicological tests are given, including guidance for future research. This review reinforces the use of the ZET as a suitable approach to assess the health risks of NM exposure.
Afficher plus [+] Moins [-]The zebrafish embryotoxicity test (ZET) for nanotoxicity assessment: from morphological to molecular approach Texte intégral
2019
Pereira, Aryelle Canedo | Gomes, Tânia | Ferreira Machado, Mônica Rodrigues | Rocha, Thiago Lopes
Embargo until 28 June 2021 | Nanotechnology and use of nanomaterials (NMs) improve life quality, economic growth and environmental health. However, the increasing production and use of NMs in commercial products has led to concerns about their potential toxicity on human and environment health, as well as its toxicological classification and regulation. In this context, there is an urgent need to standardize and validate procedures for nanotoxicity testing. Since the zebrafish embryotoxicity test (ZET) has been indicated as a suitable approach for the toxicity assessment of traditional and emergent pollutants, the aim of this review is to summarize the existing literature on embryotoxic and teratogenic effects of NMs on zebrafish. In addition, morphological changes in zebrafish embryos induced by NMs were classified in four reaction models, allowing classification of the mode of action and toxicity of different types of NM. Revised data showed that the interaction and bioaccumulation of NMs on zebrafish embryos were associated to several toxic effects, while the detoxification process was limited. In general, NMs induced delayed hatching, circulatory changes, pigmentation and tegumentary alterations, musculoskeletal disorders and yolk sac alterations on zebrafish embryos. Recommendations for nanotoxicological tests are given, including guidance for future research. This review reinforces the use of the ZET as a suitable approach to assess the health risks of NM exposure. | publishedVersion
Afficher plus [+] Moins [-]Di(n-butyl) phthalate exposure impairs meiotic competence and development of mouse oocyte Texte intégral
2019
Li, Fei-Ping | Zhou, Jie-Long | Guo, Ai-Wei | Liu, Yu | Zhang, Fei | Xu, Bai-Hui | Liu, Rui | Wang, Ya-Long | Chen, Ming-Huang | Lin, Yan-Hong | He, Shu-Wen | Liao, Bao-Qiong | Fu, Xian-Pei | Wang, Hai Long
Di(n-butyl) phthalate (DBP) is extensively used in industrial applications as plasticizer and stabilizer and its presence in the environment may present health risks for human. Previous studies have demonstrated its mutagenic, teratogenic, and carcinogenic ability. However, its effect on mammalian oocyte maturation remains unknown. In this study, we examined the effect of DBP on oocyte maturation both in vitro and in vivo. Our results showed that DBP could significantly reduce mice oocyte germinal vesicle breakdown (GVBD) and polar body extrusion (PBE) rates. In addition, oocyte cytoskeleton was damaged and cortical granule-free domains (CGFDs) were also disrupted. Finally, DBP induced early apoptosis of oocyte and granulosa cells (GCs). Collectively, these data demonstrate that DBP could reduce meiosis competence and mouse oocyte development.
Afficher plus [+] Moins [-]Polluted water from an urban reservoir (Madín dam, México) induces toxicity and oxidative stress in Cyprinus carpio embryos Texte intégral
2019
Pérez-Coyotl, I. | Galar-Martínez, M. | García-Medina, S. | Gómez-Oliván, L.M. | Gasca- Pérez, E. | Martínez-Galero, E. | Islas-Flores, H. | Pérez-Pastén, Borja R. | Barceló, D. | López de Alda, M. | Pérez-Solsona, S. | Serra-Roig, M.P. | Montemurro, N. | Peña-Herrera, J.M. | Sánchez-Aceves, L.M.
Polluted water from an urban reservoir (Madín dam, México) induces toxicity and oxidative stress in Cyprinus carpio embryos Texte intégral
2019
Pérez-Coyotl, I. | Galar-Martínez, M. | García-Medina, S. | Gómez-Oliván, L.M. | Gasca- Pérez, E. | Martínez-Galero, E. | Islas-Flores, H. | Pérez-Pastén, Borja R. | Barceló, D. | López de Alda, M. | Pérez-Solsona, S. | Serra-Roig, M.P. | Montemurro, N. | Peña-Herrera, J.M. | Sánchez-Aceves, L.M.
The Madín Dam is a reservoir located in the municipalities of Naucalpan and Atizapán, in the metropolitan area adjacent to Mexico City. The reservoir supplies drinking water to nearby communities and provides an area for various recreational activities, including kayaking, sailing and carp fishing. Over time, the number of specimens of common carp has notably diminished in the reservoir, which receives direct domestic drainage from two towns as well as numerous neighborhoods along the Tlalnepantla River. Diverse studies have demonstrated that the pollutants in the water of the reservoir produce oxidative stress, genotoxicity and cytotoxicity in juvenile Cyprinus carpio, possibly explaining the reduction in the population of this species; however, it is necessary to assess whether these effects may also be occurring directly in the embryos. Hence, surface water samples were taken at five sites and pharmaceutical drugs, personal care products (especially sunscreens), organophosphate and organochlorine pesticides, and other persistent organic pollutants (e.g., polychlorinated biphenyls and polycyclic aromatic hydrocarbons) were identified. Embryos of C. carpio were exposed to the water samples to evaluate embryolethality, modifications in embryonic development, lipoperoxidation, the quantity of hydroperoxide and oxidized proteins, and antioxidant enzyme activity (superoxide dismutase, catalase and glutathione peroxidase). It was found that the polluted water of the Madín Dam gave rise to embryolethality, embryotoxicity, congenital abnormalities, and oxidative stress on the common carp embryos.
Afficher plus [+] Moins [-]Polluted water from an urban reservoir (Madín dam, México) induces toxicity and oxidative stress in Cyprinus carpio embryos Texte intégral
2019
Pérez-Coyotl, I. | Galar-Martínez, Marcela | García-Medina, Sandra | Gómez-Oliván, Leobardo Manuel | Gasca-Pérez, Eloy | Islas-Flores, Hariz | Pérez-Pastén-Borja, Ricardo | Barceló, Damià | López de Alda, Miren | Pérez Solsona, Sandra | Serra-Roig, M. Pau | Montemurro, Nicola | Peña-Herrera, Juan Manuel | Sánchez-Aceves, Livier Mireya | Barceló, Damià [0000-0002-8873-0491] | López De Alda, Miren [0000-0002-9347-2765] | Perez, Sandra [0000-0002-3179-3969] | Montemurro, Nicola [0000-0002-7496-203X] | Peña-Herrera, Juan Manuel [0000-0002-9677-6457] | Consejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]
The Madín Dam is a reservoir located in the municipalities of Naucalpan and Atizapán, in the metropolitan area adjacent to Mexico City. The reservoir supplies drinking water to nearby communities and provides an area for various recreational activities, including kayaking, sailing and carp fishing. Over time, the number of specimens of common carp has notably diminished in the reservoir, which receives direct domestic drainage from two towns as well as numerous neighborhoods along the Tlalnepantla River. Diverse studies have demonstrated that the pollutants in the water of the reservoir produce oxidative stress, genotoxicity and cytotoxicity in juvenile Cyprinus carpio, possibly explaining the reduction in the population of this species; however, it is necessary to assess whether these effects may also be occurring directly in the embryos. Hence, surface water samples were taken at five sites and pharmaceutical drugs, personal care products (especially sunscreens), organophosphate and organochlorine pesticides, and other persistent organic pollutants (e.g., polychlorinated biphenyls and polycyclic aromatic hydrocarbons) were identified. Embryos of C. carpio were exposed to the water samples to evaluate embryolethality, modifications in embryonic development, lipoperoxidation, the quantity of hydroperoxide and oxidized proteins, and antioxidant enzyme activity (superoxide dismutase, catalase and glutathione peroxidase). It was found that the polluted water of the Madín Dam gave rise to embryolethality, embryotoxicity, congenital abnormalities, and oxidative stress on the common carp embryos. Capsule: The water of the Madín dam contains a complex mixture of pollutants, including hydrocarbons, which produce oxidative stress and embryotoxicity on Cyprinus carpio. © 2019 Elsevier Ltd | This study was made possible by financial support from the Consejo Nacional de Ciencia y Tecnología (CONACyT-Mexico, project #181541 and Cátedras CONACyT, #282), and the Secretaría de Investigación y Posgrado of the Instituto Politécnico Nacional (SIP-IPN, project #20160871 and 20180699). We give thanks to Biologist Gerardo Ontiveros at the Centro Carpícola Tiacaque for supplying the test specimens and giving advice on their care and maintenance. | Peer reviewed
Afficher plus [+] Moins [-]Degradation of cyclophosphamide and 5-fluorouracil by UV and simulated sunlight treatments: Assessment of the enhancement of the biodegradability and toxicity Texte intégral
2016
Lutterbeck, Carlos Alexandre | Wilde, Marcelo Luís | Baginska, Ewelina | Leder, Christoph | Machado, Ênio Leandro | Kümmerer, Klaus
The presence of pharmaceuticals in the environment has triggered concern among the general population and received considerable attention from the scientific community in recent years. However, only a few publications have focused on anticancer drugs, a class of pharmaceuticals that can exhibit cytotoxic, genotoxic, mutagenic, carcinogenic and teratogenic effects. The present study investigated the photodegradation, biodegradation, bacterial toxicity, mutagenicity and genotoxicity of cyclophosphamide (CP) and 5-fluorouracil (5-FU). The photodegradation experiments were performed at a neutral to slight pH range (7–7.8) using two different lamps (medium-pressure mercury lamp and a xenon lamp). The primary elimination of the parent compounds was monitored by means of liquid chromatography tandem mass spectrometry (LC-IT-MS/MS). NPOC (non-purgeable organic carbon) analyses were carried out in order to assess mineralization rates. The Closed Bottle Test (CBT) was used to assess ready biodegradability. A new method using Vibrio fischeri was adopted to evaluate toxicity. CP was not degraded by any lamp, whereas 5-FU was completely eliminated by irradiation with the mercury lamp but only partially by the Xe lamp. No mineralization was observed for the experiments performed with the Xe lamp, and a NPOC removal of only 18% was registered for 5-FU after 256 min using the UV lamp. Not one of the parent compounds was readily biodegradable in the CBT. Photo transformation products (PTPs) resulting from photolysis were neither better biodegradable nor less toxic than the parent compound 5-FU. In contrast, the results of the tests carried out with the UV lamp indicated that more biodegradable and non-toxic PTPs of 5-FU were generated. Three PTPs were formed during the photodegradation experiments and were identified. The results of the in silico QSAR predictions showed positive mutagenic and genotoxic alerts for 5-FU, whereas only one of the formed PTPs presented positive alerts for the genotoxicity endpoint.
Afficher plus [+] Moins [-]Effects of the antineoplastic drug cyclophosphamide on the biochemical responses of the mussel Mytilus galloprovincialis under different temperatures Texte intégral
2021
Queirós, Vanessa | Azeiteiro, Ulisses M. | Barata, Carlos | Santos, Juan Luis | Alonso, Esteban | Soares, Amadeu M.V.M. | Freitas, Rosa
Effects of the antineoplastic drug cyclophosphamide on the biochemical responses of the mussel Mytilus galloprovincialis under different temperatures Texte intégral
2021
Queirós, Vanessa | Azeiteiro, Ulisses M. | Barata, Carlos | Santos, Juan Luis | Alonso, Esteban | Soares, Amadeu M.V.M. | Freitas, Rosa
Cyclophosphamide (CP) is an antineoplastic drug widely used in chemotherapy treatments with high consumption rates and that has been detected in the aquatic environment. After being released into the aquatic environment, CP may cause adverse effects on aquatic organisms since antineoplastics are well-known cytotoxic, genotoxic, mutagenic and teratogenic drugs. Moreover, predicted environmental changes, such as the temperature rising, may alter the impacts caused by CP on organisms. Thus, the present study aimed to assess the effects caused by CP chronic exposure in the mussel Mytilus galloprovincialis, under actual and predicted warming scenarios. Organisms were exposed for 28 days to different concentrations of CP (10, 100, 500 and 1000 ng/L) at control (17 ± 1.0 °C) and increased (21 ± 1.0 °C) temperatures. Biochemical responses related to metabolic capacity, energy reserves, oxidative stress and neurotoxicity were assessed. The results showed that the organisms were able to maintain their metabolic capacity under all exposure conditions. However, their antioxidant defense mechanisms were activated mostly at higher CP concentrations being able to prevent cellular damage, even under the warming scenario. Overall, the present findings suggest that temperature rise may not alter the impacts of CP towards M. galloprovincialis.
Afficher plus [+] Moins [-]Effects of the antineoplastic drug cyclophosphamide on the biochemical responses of the mussel Mytilus galloprovincialis under different temperatures Texte intégral
2021
Queirós, Vanessa | Azeiteiro, Ulisses M | Barata Martí, Carlos | Santos, Juan Luis | Alonso, Esteban | Soares, Amadeu M. V. M. | Freitas, Rosa | 0000-0001-6426-0512 | 0000-0001-9704-1316 | 0000-0002-1647-9226 | 0000-0003-0879-9470 | Consejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]
Cyclophosphamide (CP) is an antineoplastic drug widely used in chemotherapy treatments with high consumption rates and that has been detected in the aquatic environment. After being released into the aquatic environment, CP may cause adverse effects on aquatic organisms since antineoplastics are well-known cytotoxic, genotoxic, mutagenic and teratogenic drugs. Moreover, predicted environmental changes, such as the temperature rising, may alter the impacts caused by CP on organisms. Thus, the present study aimed to assess the effects caused by CP chronic exposure in the mussel Mytilus galloprovincialis, under actual and predicted warming scenarios. Organisms were exposed for 28 days to different concentrations of CP (10, 100, 500 and 1000 ng/L) at control (17 ± 1.0 °C) and increased (21 ± 1.0 °C) temperatures. Biochemical responses related to metabolic capacity, energy reserves, oxidative stress and neurotoxicity were assessed. The results showed that the organisms were able to maintain their metabolic capacity under all exposure conditions. However, their antioxidant defense mechanisms were activated mostly at higher CP concentrations being able to prevent cellular damage, even under the warming scenario. Overall, the present findings suggest that temperature rise may not alter the impacts of CP towards M. galloprovincialis. | Vanessa Queirós benefited from a PhD grant (PD/BD/150590/2020) given by the National Funds through the Portuguese Science Foundation (Fundação para a Ciência e a Tecnologia, FCT). Thanks are due for the financial support to CESAM (UIDB/50017/2020+UIDP/50017/2020). | Peer reviewed
Afficher plus [+] Moins [-]Bisphenol A exposure induces apoptosis and impairs early embryonic development in Xenopus laevis Texte intégral
2021
Ge, Yaming | Ren, Fei | Chen, Lingli | Hu, Dongfang | Wang, Xinrui | Cui, Yunli | Suo, Yu | Zhang, Hongli | He, Junping | Yin, Zhihong | Ning, Hongmei
Bisphenol A (BPA), an endocrine-disrupting chemical that is largely produced and used in the plastics industry, causes environmental pollution and is absorbed by humans through consumption of food and liquids in polycarbonate containers. BPA exerts developmental and genetic toxicities to embryos and offsprings, but the embryotoxicity mechanism of this chemical is unclear. This study aimed to explore the toxic effect of BPA on embryonic development and elucidate its toxicity mechanism. Embryos of Xenopus laevis as a model were treated with different concentrations (0.1, 1, 10, and 20 μM) of BPA at the two-cell stage to investigate the developmental toxicity of BPA. Embryonic development and behaviors were monitored 24 h–96 h of BPA exposure. BPA concentrations greater than 1 μM exerted significant teratogenic effects on the Xenopus embryos, which showed short tail axis, miscoiled guts, and bent notochord as the main malformations. The 20 μM BPA-treated embryos were seriously damaged in all aspects and exhibited deformity, impaired behavioral ability, and tissue damage. The DNA integrity and apoptosis of the Xenopus embryos were also investigated. Exposure to BPA concentrations higher than 0.1 μM significantly induced DNA damage (p < 0.05). The 10 and 20 μM BPA-treated embryos exhibited higher levels of cleaved caspase-3 protein than the control. The ratios of bax/bcl-2 mRNA were significantly higher in the 10 μM and 20 μM-treated embryos than the ratio in the control group. Overall, data indicated that BPA can delay the early development, induce DNA damage and apoptosis, and eventually cause multiple malformations in Xenopus embryos.
Afficher plus [+] Moins [-]The fish early-life stage sublethal toxicity syndrome – A high-dose baseline toxicity response Texte intégral
2021
Meador, James P.
A large number of toxicity studies report abnormalities in early life-stage (ELS) fish that are described here as a sublethal toxicity syndrome (TxSnFELS) and generally include a reduced heart rate, edemas (yolk sac and cardiac), and a variety of morphological abnormalities. The TxSnFELS is very common and not diagnostic for any chemical or class of chemicals. This sublethal toxicity syndrome is mostly observed at high exposure concentrations and appears to be a baseline, non-specific toxicity response; however, it can also occur at low doses by specific action. Toxicity metrics for this syndrome generally occur at concentrations just below those causing mortality and have been reported for a large number of diverse chemicals. Predictions based on tissue concentrations or quantitative-structure activity relationship (QSAR) models support the designation of baseline toxicity for many of the tested chemicals, which is confirmed by observed values. Given the sheer number of disparate chemicals causing the TxSnFELS and correlation with QSAR derived partitioning; the only logical conclusion for these high-dose responses is baseline toxicity by nonspecific action and not a lock and key type receptor response. It is important to recognize that many chemicals can act both as baseline toxicants and specific acting toxicants likely via receptor interaction and it is not possible to predict those threshold doses from baseline toxicity. We should search out these specific low-dose responses for ecological risk assessment and not rely on high-concentration toxicity responses to guide environmental protection. The goal for toxicity assessment should not be to characterize toxic responses at baseline toxicity concentrations, but to evaluate chemicals for their most toxic potential. Additional aspects of this review evaluated the fish ELS teratogenic responses in relation to mammalian oral LD50s and explored potential key events responsible for baseline toxicity.
Afficher plus [+] Moins [-]Disinfection by-products in drinking water: Occurrence, toxicity and abatement Texte intégral
2020
Srivastav, Arun Lal | Patel, Naveen | Chaudhary, Vinod Kumar
Disinfection means the killing of pathogenic organisms (e.g. bacteria and its spores, viruses, protozoa and their cysts, worms, and larvae) present in water to make it potable for other domestic works. The substances used in the disinfection of water are known as disinfectants. At municipal level, chlorine (Cl₂), chloramines (NH₂Cl, NHCl₂), chlorine dioxide (ClO₂), ozone (O₃) and ultraviolet (UV) radiations, are the most commonly used disinfectants. Chlorination, because of its removal efficiency and cost effectiveness, has been widely used as method of disinfection of water. But, disinfection process may add several kinds of disinfection by-products (DBPs) (∼600–700 in numbers) in the treated water such as Trihalomethanes (THM), Haloacetic acids (HAA) etc. which are detrimental to the human beings in terms of cytotoxicity, mutagenicity, teratogenicity and carcinogenicity. In water, THMs and HAAs were observed in the range from 0.138 to 458 μg/L and 0.16–136 μg/L, respectively. Thus, several regulations have been specified by world authorities like WHO, USEPA and Bureau of Indian Standard to protect human health. Some techniques have also been developed to remove the DBPs as well as their precursors from the water. The popular techniques of DBPs removals are adsorption, advance oxidation process, coagulation, membrane based filtration, combined approaches etc. The efficiency of adsorption technique was found up to 90% for DBP removal from the water.
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