RESUMO
This research aimed to develop natural plant systems to serve as biological sentinels for the detection of organophosphate pesticides in the environment. The working hypothesis was that the presence of the pesticide in the environment caused changes in the content of pigments and in the photosynthetic functioning of the plant, which could be evaluated non-destructively through the analysis of reflected light and emitted fluorescence. The objective of the research was to furnish in vivo indicators derived from spectroscopic parameters, serving as early alert signals for the presence of organophosphates in the environment. In this context, the effects of two pesticides, Chlorpyrifos and Dimethoate, on the spectroscopic properties of aquatic plants (Vallisneria nana and Spathyfillum wallisii) were studied. Chlorophyll-a variable fluorescence allowed monitoring both pesticides' presence before any damage was observed at the naked eye, with the analysis of the fast transient (OJIP curve) proving more responsive than Kautsky kinetics, steady-state fluorescence, or reflectance measurements. Pesticides produced a decrease in the maximum quantum yield of PSII photochemistry, in the proportion of PSII photochemical deexcitation relative to PSII non photochemical decay and in the probability that trapped excitons moved electrons into the photosynthetic transport chain beyond QA-. Additionally, an increase in the proportion of absorbed energy being dissipated as heat rather than being utilized in the photosynthetic process, was notorious. The pesticides induced a higher deactivation of chlorophyll excited states by photophysical pathways (including fluorescence) with a decrease in the quantum yields of photosystem II and heat dissipation by non-photochemical quenching. The investigated aquatic plants served as sentinels for the presence of pesticides in the environment, with the alert signal starting within the first milliseconds of electronic transport in the photosynthetic chain. Organophosphates damage animals' central nervous systems similarly to certain compounds found in chemical weapons, thus raising the possibility that sentinel plants could potentially signal the presence of such weapons.
Assuntos
Clorofila , Clorpirifos , Clorofila/metabolismo , Clorofila/química , Clorpirifos/metabolismo , Clorpirifos/toxicidade , Fluorescência , Praguicidas/toxicidade , Praguicidas/metabolismo , Fotossíntese/efeitos dos fármacos , Dimetoato/toxicidade , Dimetoato/metabolismo , Espectrometria de Fluorescência , Complexo de Proteína do Fotossistema II/metabolismo , Complexo de Proteína do Fotossistema II/química , Monitoramento Ambiental/métodos , Clorofila A/metabolismo , Clorofila A/química , Cinética , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade , Poluentes Químicos da Água/metabolismoRESUMO
Although it is known that organophosphate insecticides are harmfull to aquatic ecosystems, oxidative damages caused by Dimethoate and Chlorpyrifos are not studied on Arthrospira platensis Gomont. In this study, various Chlorpyrifos (0-150 µg mL-1) and Dimethoate (0-250 µg mL-1) concentrations were added to the culture medium in laboratory to evaulate growth rate, chlorophyll-a content and antioxidant parameters of A. platensis. Optical Density (OD560) and chlorophyll-a decreased compared to the control for seven days in both pesticide applications. Superoxide dismutase (SOD) activity increased at 50 µg mL-1 Chlorpyrifos concentration but it decreased at all concentrations. Although Ascorbate peroxidase (APX) and glutathione reductase (GR) activities increased with Chlorpyrifos application, they did not change with Dimethoate application. Malondialdehyde (MDA) amount decreased at 150 µg mL-1 Chlorpyrifos concentration but it increased in Dimethoate application. The H2O2 content were increased in both applications. Proline decreased in 50 and 75 µg mL-1 Chlorpyrifos concentrations and increased at 150 µg mL-1 concentration, while it increased at 25 µg mL-1 Dimethoate concentration. The results were tested at 0.05 significance level. These pesticides inhibit A. platensis growth and chlorophyll-a production and cause oxidative stress. The excessive use may affect the phytoplankton and have negative consequences in the aquatic ecosystem.
Assuntos
Clorpirifos , Inseticidas , Praguicidas , Inseticidas/toxicidade , Clorpirifos/toxicidade , Dimetoato/toxicidade , Ecossistema , Peróxido de Hidrogênio , Estresse Oxidativo , Praguicidas/toxicidade , Antioxidantes , Clorofila , Clorofila A , Compostos OrganofosforadosRESUMO
Currently, only Apis mellifera is used in environmental regulation to evaluate the hazard of pesticides to pollinators. The low representativeness of pollinators and bee diversity in this approach may result in insufficient protection for the wild species. This scenario is intensified in tropical environments, where little is known about the effects of pesticides on solitary bees. We aimed to calculate the medium lethal dose (LD50) and medium lethal concentration (LC50) of the insecticide dimethoate in the Neotropical solitary bee Centris analis, a cavity-nesting, oil-collecting bee distributed from Brazil to Mexico. Males and females of C. analis were exposed orally to dimethoate for 48 h under laboratory conditions. Lethality was assessed every 24 h until 144 h after the beginning of the test. After the LD50 calculation, we compared the value with available LD50 values in the literature of other bee species using the species sensitivity distribution curve. In 48 h of exposure, males showed an LD50 value 1.33 times lower than females (32.78 and 43.84 ng active ingredient/bee, respectively). Centris analis was more sensitive to dimethoate than the model species A. mellifera and the solitary bee from temperate zones, Osmia lignaria. However, on a body weight basis, C. analis and A. mellifera had similar LD50 values. Ours is the first study that calculated an LD50 for a Neotropical solitary bee. Besides, the results are of crucial importance for a better understanding of the effects of pesticides on the tropical bee fauna and will help to improve the risk assessment of pesticides to bees under tropical conditions, giving attention to wild species, which are commonly neglected. Environ Toxicol Chem 2023;42:2758-2767. © 2023 SETAC.
Assuntos
Himenópteros , Inseticidas , Praguicidas , Feminino , Abelhas , Animais , Inseticidas/toxicidade , Praguicidas/toxicidade , Dimetoato/toxicidade , Medição de RiscoRESUMO
This work attempts to evaluate dermal exposure (DE) of farm workers to dimethoate after 4 h of routine application to a lemon plantation. Dimethoate was measured on the workers' clothes as well as in stratum corneum (SC) and in saliva. In vitro permeation tests (IVPT) were performed through rat, pig and human skin and pig buccal, esophageal and sublingual mucosas. The mean of dimethoate DE was 342.19 ± 487.14 mg/d, the percentage of toxic dose per hour was higher than the other pesticides, and the SC penetration factors ranged between 0.5 and 14.81 and 0.05-53.96 % for back of neck and arms respectively. In the supporting IVPT study, dimethoate absorption through human skin was 14.75 % and the default value in the absence of experimental data for this product is 70%. These results show that in family farming the deficiency of correct clothing during the application of pesticides leaves workers more vulnerable.
Assuntos
Praguicidas , Absorção Cutânea , Agricultura , Animais , Dimetoato/toxicidade , Humanos , Praguicidas/metabolismo , Ratos , Pele/metabolismo , SuínosRESUMO
Organophosphate insecticides such as dimethoate (DMT) are widely used in agriculture. As a side effect, however, these insecticides contaminate bodies of water, resulting in damage to aquatic organisms. The development of nanopesticides may be an innovative alternative in the control of agricultural pests, increasing effectiveness and reducing their toxicological effects. Based upon this, the present study has investigated encapsulated DMT in alginate chitosan nanoparticles (nanoDMT) and evaluated its toxicological effects on non-target organisms. The nanoparticles were characterized by DLS, NTA and AFM, as well as being evaluated by the release profile. Nanoparticle toxicity was also evaluated in comparison with DMT, empty nanoparticles and DMT (NP + DMT), and commercial formulations (cDMT), in the embryos and larvae of Danio rerio (zebrafish) according to lethality, morphology, and behavior. The nanoparticle control (NP) showed hydrodynamic size values of 283 ± 4 nm, a PDI of 0.5 ± 0.05 and a zeta potential of -31 ± 0.4 mV. For nanoparticles containing dimethoate, the nanoparticles showed 301 ± 7 nm size values, a PDI of 0.45 ± 0.02, a zeta potential of -27.9 ± 0.2 mV, and an encapsulation of 75 ± 0.32%, with slow-release overtime (52% after 48 h). The AFM images showed that both types of nanoparticles showed spherical morphology. Major toxic effects on embryo larval development were observed in commercial dimethoate exposure followed by the technical pesticide, predominantly in the highest tested concentrations. With regard to the toxic effects of sodium alginate/chitosan, although there was an increase for LC50-96 h concerning the technical dimethoate, the behavior of the larvae was not affected. The data obtained demonstrate that nanoencapsulated dimethoate reduces the toxicity of insecticides on zebrafish larvae, suggesting that nanoencapsulation may be safer for non-target species, by eliminating collateral effects and thus promoting sustainable agriculture.
Assuntos
Quitosana , Inseticidas , Nanopartículas , Alginatos/farmacologia , Animais , Quitosana/farmacologia , Dimetoato/toxicidade , Inseticidas/toxicidade , Larva , Nanopartículas/toxicidade , Peixe-ZebraRESUMO
Among the factors implicated in amphibian global decline, agrochemicals have been gaining increasing attention. In order to evaluate the toxicity of a dimethoate-based insecticide on the early development of an autochthonous amphibian, Rhinella arenarum, continuous and 24 h pulse exposure bioassays were carried out. Lethal and sublethal effects, neurotoxicity and the ecological risk were assessed. Results demonstrate that larvae were more sensitive than embryos with 504 h-LC50 of 12.82 and 16.38 mg L-1, respectively. 24 h pulse experiments showed a high toxicity increment at early embryonic stages, while the sensitivity at later stages was high and constant. Dimethoate caused teratogenesis and several sublethal effects as morphological and behavioral alterations but also disruption in the metamorphic process. About neurotoxicity, dimethoate inhibited the activity of butyrylcholinesterase at 0.5 and 1 mg L-1 exposed larvae. The results obtained in this study as the risk assessment revealed that dimethoate represents a hazard on Rhinella arenarum survival and development but also a potential risk for the continuity of the populations of this species in agroecosystems.
Assuntos
Dimetoato , Praguicidas , Animais , Bufo arenarum , Butirilcolinesterase , Dimetoato/toxicidade , Embrião não Mamífero , Larva , Praguicidas/toxicidadeRESUMO
Dimethoate ([O,O-dimethyl S-(N-methylcarbamoylmethyl) phosphorodithioate]) is an organophosphate insecticide and acaricide widely used for agricultural purposes. Genotoxicity refers to the ability of a chemical agent interact directly to DNA or act indirectly leading to DNA damage by affecting spindle apparatus or enzymes involved in DNA replication, thereby causing mutations. Taking into consideration the importance of genotoxicity induced by dimethoate, the purpose of this manuscript was to provide a mini review regarding genotoxicity induced by dimethoate as a result of oxidative stress. The present study was conducted on studies available in MEDLINE, PUBMED, EMBASE, and Google scholar for all kind of articles (all publications published until May, 2020) using the following key words: dimethoate, omethoate, DNA damage, genetic damage, oxidative stress, genotoxicity, mutation, and mutagenicity. The results showed that many studies were published in the scientific literature; the approach was clearly demonstrated in multiple tissues and organs, but few papers were designed in humans. In summary, new studies within the field are important for better understanding the pathobiological events of genotoxicity on human cells, particularly to explain what cells and/or tissues are more sensitive to genotoxic insult induced by dimethoate.
Assuntos
Dimetoato , Inseticidas , Dano ao DNA , Dimetoato/toxicidade , Humanos , Inseticidas/toxicidade , Mutagênicos/toxicidade , Estresse OxidativoRESUMO
There is a great concern worldwide about the global decline of amphibians, particularly by agrochemical pollution. The aim of this study was to assess oxidative stress and genotoxicity of a commercial formulation of the insecticide dimethoate in Rhinella arenarum larvae, using sublethal biomarkers. The 24- and 96-h LC50 values of dimethoate to R. arenarum were 48.81 and 38.86 mg L-1, while the 96-h no observed effect concentration (NOEC) value was 20 mg L-1. For sublethal biomarker assays, R. arenarum larvae were exposed to 1.25, 2.5, and 5% of the 96-h NOEC (0.25, 0.5, and 1 mg L-1 dimethoate, respectively). After 96 h of exposure, inhibition of catalase (CAT) and glutathione S-transferase (GST) activities were registered. Also, an increased superoxide dismutase (SOD) activity was observed in larvae exposed to the highest concentration (1 mg L-1). Lipid peroxidation by increased thiobarbituric acid reactive substance levels in larvae exposed to 0.5 and 1 mg L-1 was detected. No differences in micronuclei frequency between treatments and negative control were observed. These results demonstrate the oxidative toxicity of dimethoate at sublethal concentrations in Rhinella arenarum larvae. The disruption of defense mechanisms may contribute to a deleterious impact on amphibian populations from habitats exposed to this organophosphorus insecticide.
Assuntos
Dimetoato , Inseticidas , Animais , Dimetoato/toxicidade , Glutationa Transferase/metabolismo , Inseticidas/toxicidade , Larva/metabolismo , Compostos Organofosforados , Estresse OxidativoRESUMO
In northern Sinaloa state, Mexico, little is known on organophosphate pesticide transport and fate in agricultural drainage systems. Spatial and temporal variation of chlorpyrifos and dimethoate was assessed in two agricultural drainage ditches (Buenaventura and Burrión) and risk for aquatic life was estimated. Analysis was made by high performance liquid chromatography and risk estimates were determined following international reference frameworks. In water, the highest chlorpyrifos concentration in the Buenaventura ditch was 5.49 µg L-1, and 3.43 µg L-1 in the Burrión ditch. Dimethoate was quantified only once in both ditches (0.44 µg L-1 and 0.49 µg L-1). In sediment, chlorpyrifos was quantified only in the Burrión ditch (242 µg kg-1). Chlorpyrifos concentrations surpassed water and sediment quality criteria, representing a hazard for environmental and human health, as both ditches discharge into the Gulf of California and are used for capture of commercial species such as the grey mullet (Mugil cephalus) and cauque prawn (Macrobrachium americanum).
Assuntos
Clorpirifos , Poluentes Químicos da Água , Agricultura , Dimetoato , Sedimentos Geológicos , Humanos , México , Água , Poluentes Químicos da Água/análiseRESUMO
A simple and rapid method for the determination of dimethoate in water was developed based on the monitoring of the complex formation between bis 5-phenyldipyrrinate of nickel (II) and the herbicide dimethoate. The method showed a short response time (10 s), high selectivity (very low interference from other sulfate and salts), high sensitivity (limit of detection (LOD) 0.45 µM, limit of quantitation (LOQ) of 1.39 µM), and a Kd of 2.4 µM. Stoichiometry experiments showed that complex formation occurred with a 1:1 relation. The method was applied to different environmental water samples such as lagoon, stream, urban, and groundwater samples. The results indicated that independently from the water source, the method exhibited high precision (0.25-2.47% variation coefficient) and accuracy (84.42-115.68% recovery). In addition, the method was also tested using an effluent from a wastewater treatment plant from Mexico; however, the results indicated that the presence of organic matter had a pronounced effect on the detection.