Harmonização e classificação toxicológica de agrotóxicos em 1992 no Brasil e a necessidade de prever os impactos da futura implantação do GHS

Em 1992, o Brasil modificou seus critérios de classificação toxicológica de agrotóxicos adequando-os à recomendação de classificação de periculosidade da Organização Mundial da Saúde (OMS). Em 2002, o Sistema Globalmente Harmonizado de Classificação e Rotulagem de Produtos Químicos (GHS) foi adotado pela Organização das Nações Unidas. Em decorrência, a OMS está adequando ao GHS sua recomendação de classificação de agrotóxicos, o que também deverá ser feito pelo Brasil. Considerou-se oportuno estimar o impacto da alteração de critérios, ocorrida em 1992, na reclassificação toxicológica dos produtos comerciais que se encontravam registrados na ocasião. Encontrou-se que 58,6% do total dos agrotóxicos então registrados (74,9% das formulações líquidas e 31,0% das sólidas) podem ter sofrido reclassificação para classes toxicológicas consideradas de me-nor periculosidade, sofrendo mudanças na comunicação de riscos expressa na rotulagem. Isto pode ter ocasionado conseqüências negativas devido a confusões de interpretação pelos agricultores. Nos países que já dispõem de sistemas de classificação de periculosidade de agrotóxicos, como o Brasil, recomenda-se estimar, antes da implantação, os impactos das mudanças que poderão decorrer da adoção do GHS.

Harmonização e classificação de periculosidade de agrotóxicos: impactos na classificação toxicológica, Brasil, 1992

Em 1992 o Brasil modificou seus critérios de classificação toxicológica de agrotóxicos adequando-os à recomendação de classificação de periculosidade da Organização Mundial da Saúde (OMS). Em 2002, o Sistema Globalmente Harmonizado de Classificação e Rotulagem de Produtos Químicos (GHS) foi adotado pela Organização das Nações Unidas. Em decorrência, a OMS está adequando ao GHS sua recomendação de classificação de agrotóxicos, o que também deverá ser feito pelo Brasil. Considerou-se oportuno estimar o impacto da alteração de critérios, ocorrida em 1992, na reclassificação toxicológica dos produtos comerciais que se encontravam registrados na ocasião. Encontrou-se que 58,6% do total dos agrotóxicos então registrados (74,9% das formulações líquidas e 31,0% das sólidas) podem ter sofrido reclassificação para Classes Toxicológicas consideradas de menor periculosidade, sofrendo mudanças na comunicação de riscos expressa na rotulagem. Isto pode ter ocasionado conseqüências negativas devido à confusões de interpretação pelos agricultores. Nos países que já dispõem de sistemas de classificação de periculosidade de agrotóxicos, como o Brasil, recomenda-se estimar, antes da implantação, os impactos das mudanças que poderão decorrer da adoção do GHS

O uso de praguicidas nas psiculturas e pesqueiros situados na bacia do rio Mogi-Guaçu

The use of pesticides has been the main strategy to prevent ectoparasites that threaten aquaculture productivity. The non regulated use of such chemicals may lead to damage in aquatic ecosystems that receive the ponds effluents, compromising environmental and consumers' health. With the aim of evaluate the use of pesticides in aquacultural practices developed in Mogi-Guacu catchment, fish farm and fee fishing owners were interviewed. Eighty-nine enterprises were visited, and was verified that about 40% uses pesticide during management practices in recent years. The diflubenzuron, methyl parathion, trichlorfon and triflumuron were the pesticides most used. In addition to the interviews, samples were taken in 3 enterprises localized in Socorro, SP (Peixe River sub-catchment) which had a pesticide usage history. It was not detected residues of the pesticides diflubenzuron, methyl parathion and dichlorvos in any water, sediments nor fishes samples from tow distinct seasons (lower and high fishing seasons). On fact, non-detected pesticides residues corroborate with the fish farmers statement to deny recently pesticide usage during management practices. Nevertheless, the lack of chemotherapeutics usage criteria and the potential hazardous due to these practices were discussed.

Antimicrobial Activity of Diterpenes from Viguiera arenaria against Endodontic Bacteria

Six pimarane-type diterpenes isolated from Viguiera arenaria Baker and two semi-synthetic derivatives were evaluated in vitro against a panel of representative microorganisms responsible for dental root canal infections. The microdilution method was used for the determination of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against Porphyromonas gingivalis, Prevotella nigrescens, Prevotella intermedia, Prevotella buccae, Fusobacterium nucleatum, Bacteroides fragilis, Actinomyces naeslundii, Actinomyces viscosus, Peptostreptococcus micros, Enterococcus faecalis and Aggregatibacter actinomycetemcomitans. The compounds ent-pimara-8(14), 15-dien-19-oic acid, its sodium salt and ent-8(14), 15-pimaradien-3 beta-ol were the most active, displaying MIC values ranging from 1 to 10 mu g mL(-1). The results also allow us to conclude that minor structural differences among these diterpenes significantly influence their antimicrobial activity, bringing new perspectives to the discovery of new chemicals for use as a complement to instrumental endodontic procedures.

Anticariogenic Properties of ent-Pimarane Diterpenes Obtained by Microbial Transformation

In the present work, the anticariogenic activities of three pimarane-type diterpenes obtained by fungal biotransformation were investigated. Among these metabolites, ent-8(14), 15-pimaradien-19-ol was the most active compound, displaying very promising MIC values (ranging from 1.5 to 4.0 mu g mL(-1)) against the main microorganisms responsible for dental caries: Streptococcus salivarius, S. sobrinus, S. mutans, S. mitis, S. sanguinis, and Lactobacillus casei. Time kill assays performed with ent-8(14), 15-pimaradien-19-ol against the primary causative agent S. mutans revealed that this compound only avoids growth of the inoculum in the first 12 h (bacteriostatic effect). However, its bactericidal effect is clearly noted thereafter (between 12 and 24 h). The curve profile obtained by combining ent-8(14), 15-pimaradien-19-ol and chlorhexidine revealed a significant reduction in the time necessary for killing S. mutans compared with each of these two chemicals alone. However, no synergistic effect was observed using the same combination in the checkerboard assays against this microorganism. In conclusion, our results point out that ent-8(14), 15-pimaradien-19-ol is an important metabolite in the search for new effective anticariogenic agents.

Incidence and risk factors of aplastic anemia in Latin American countries: the LATIN case-control study

Background Associations between aplastic anemia and numerous drugs, pesticides and chemicals have been reported. However, at least 50% of the etiology of aplastic anemia remains unexplained. Design and Methods This was a case-control, multicenter, multinational study, designed to identify risk factors for agranulocytosis and aplastic anemia. The cases were patients with diagnosis of aplastic anemia confirmed through biopsy or bone marrow aspiration, selected through an active search of clinical laboratories, hematology clinics and medical records. The controls did not have either aplastic anemia or chronic diseases. A total of 224 patients with aplastic anemia were included in the study, each case was paired with four controls, according to sex, age group, and hospital where the case was first seen. Information was collected on demographic data, medical history, laboratory tests, medications, and other potential risk factors prior to diagnosis. Results The incidence of aplastic anemia was 1.6 cases per million per year. Higher rates of benzene exposure (>= 30 exposures per year) were associated with a greater risk of aplastic anemia (odds ratio, OR: 4.2; 95% confidence interval, CI: 1.82-9.82). Individuals exposed to chloramphenicol in the previous year had an adjusted OR for aplastic anemia of 8.7 (CI: 0.87-87.93) and those exposed to azithromycin had an adjusted OR of 11.02 (CI 1.14-108.02). Conclusions The incidence of aplastic anemia in Latin America countries is low. Although the research study centers had a high coverage of health services, the underreporting of cases of aplastic anemia in selected regions can be discussed. Frequent exposure to benzene-based products increases the risk for aplastic anemia. Few associations with specific drugs were found, and it is likely that some of these were due to chance alone.

Deep sequencing of New World screw-worm transcripts to discover genes involved in insecticide resistance

Background: The New World screw-worm (NWS), Cochliomyia hominivorax, is one of the most important myiasis-causing flies, causing severe losses to the livestock industry. In its current geographical distribution, this species has been controlled by the application of insecticides, mainly organophosphate (OP) compounds, but a number of lineages have been identified that are resistant to such chemicals. Despite its economic importance, only limited genetic information is available for the NWS. Here, as a part of an effort to characterize the C. hominivorax genome and identify putative genes involved in insecticide resistance, we sampled its transcriptome by deep sequencing of polyadenylated transcripts using the 454 sequencing technology. Results: Deep sequencing on the 454 platform of three normalized libraries (larval, adult male and adult female) generated a total of 548,940 reads. Eighteen candidate genes coding for three metabolic detoxification enzyme families, cytochrome P450 monooxygenases, glutathione S transferases and carboxyl/cholinesterases were selected and gene expression levels were measured using quantitative real-time polymerase chain reaction (qRT-PCR). Of the investigated candidates, only one gene was expressed differently between control and resistant larvae with, at least, a 10-fold down-regulation in the resistant larvae. The presence of mutations in the acetylcholinesterase (target site) and carboxylesterase E3 genes was investigated and all of the resistant flies presented E3 mutations previously associated with insecticide resistance. Conclusions: Here, we provided the largest database of NWS expressed sequence tags that is an important resource, not only for further studies on the molecular basis of the OP resistance in NWS fly, but also for functional and comparative studies among Calliphoridae flies. Among our candidates, only one gene was found differentially expressed in resistant individuals, and its role on insecticide resistance should be further investigated. Furthermore, the absence of mutations in the OP target site and the high frequency of mutant carboxylesterase E3 indicate that metabolic resistance mechanisms have evolved predominantly in this species.

Development of a DNA-dosimeter system for monitoring the effects of solar-ultraviolet radiation

Solar radiation sustains and affects all life forms on Earth. In recent years, the increase in environmental levels of solar-UV radiation due to depletion of the stratospheric ozone layer, as a result of anthropogenic emission of destructive chemicals, has highlighted serious issues of social concern. This becomes still more dramatic in tropical and subtropical regions, where the intensity of solar radiation is higher. To better understand the impact of the harmful effects of solar-UV radiation on the DNA molecule, we developed a reliable biological monitoring system based on the exposure of plasmid DNA to artificial UV lamps and sunlight. The determination and quanti. cation of different types of UV photoproducts were performed through the use of specific DNA repair enzymes and antibodies. As expected, a significant number of CPDs and 6-4PPs was observed when the DNA-dosimeter system was exposed to increasing doses of UVB radiation. Moreover, CPDs could also be clearly detected in plasmid DNA when this system was exposed to either UVA or directly to sunlight. Interestingly, although less abundant, 6-4PPs and oxidative DNA damage were also generated after exposure to both UVA and sunlight. These results confirm the genotoxic potential of sunlight, reveal that UVA may also produce CPDs and 6-4PPs directly in naked DNA and demonstrate the applicability of a DNA-dosimeter system for monitoring the biological effects of solar-UV radiation.

Molecular determinants of improved cathepsin B inhibition by new cystatins obtained by DNA shuffling

Background: Cystatins are inhibitors of cysteine proteases. The majority are only weak inhibitors of human cathepsin B, which has been associated with cancer, Alzheimer's disease and arthritis. Results: Starting from the sequences of oryzacystatin-1 and canecystatin-1, a shuffling library was designed and a hybrid clone obtained, which presented higher inhibitory activity towards cathepsin B. This clone presented two unanticipated point mutations as well as an N-terminal deletion. Reversing each point mutation independently or both simultaneously abolishes the inhibitory activity towards cathepsin B. Homology modeling together with experimental studies of the reverse mutants revealed the likely molecular determinants of the improved inhibitory activity to be related to decreased protein stability. Conclusion: A combination of experimental approaches including gene shuffling, enzyme assays and reverse mutation allied to molecular modeling has shed light upon the unexpected inhibitory properties of certain cystatin mutants against Cathepsin B. We conclude that mutations disrupting the hydrophobic core of phytocystatins increase the flexibility of the N-terminus, leading to an increase in inhibitory activity. Such mutations need not affect the inhibitory site directly but may be observed distant from it and manifest their effects via an uncoupling of its three components as a result of increased protein flexibility.

CHEMICAL AND PHYSICO-CHEMICAL CHARACTERIZATION OF LIGNINS OBTAINED FROM ETHANOL-WATER FRACTIONATION OF BAGASSE

Organosolv lignins can replace petroleum chemicals such as phenol either partially or totally in various applications. Eight lignins, seven of which corresponded to the ethanol-water fractionation of bagasse and the other to a reference lignin (Alcell (R)) were analyzed with the aim to evaluate their chemical and physicochemical characteristics. The purity of the lignin fractions was determined by high pressure liquid chromatography (HPLC) and by ash content. Fourier Transform-Infrared Spectroscopy (FTIR) techniques and differential UV spectroscopy were applied to identify the chemical groups in the lignin samples. The molecular weight distribution was determined by size exclusion chromatography (HPSEC). Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) techniques were used to determine the mass loss due to the high temperature treatment. The lignins studied showed the presence of p-hydroxyphenyl (H unit) and a greater proportion of guaiacyl (G unit) moieties, lower purity, similar or greater amount of phenolic hydroxyl groups, and higher degradation temperatures, than the Alcell (R) lignin.

Total soil carbon and chemical attributes under different land uses in the Brazilian savanna

Total soil carbon and chemical attributes under different land uses in the Brazilian savanna. The Brazilian savanna region (Cerrado) is one of the largest cultivated areas of the world. The different land uses in the region can effectively change the quantities of soil organic matter and the cycling of nutrients. I-lie objective of this study was to evaluate the effect of different land use management systems on the relationship between soil organic carbon and the soil chemical attributes of a Red Latosol (Oxisol) under Cerrado in Rio Verde (Goias state). The treatments studied were native vegetation (cerrado), low-productivity pasture, conventional tillage with soybean, and no-tillage with soybean and maize. The smallest values for pH, available P, K, Ca and Mg were observed for the Cerradao treatment, even if the relatively high C levels increased the potential soil cation exchange capacity. The pasture, conventional tillage and no-tillage treatments showed higher K, Ca, Mg, available 13, and S concentrations in the soil. In the areas where soil tillage did not take place and lime and fertilizers were applied superficially, the stratification of the soil organic carbon provides the retention of the elements near to the surface, with significance correlations with the soil chemicals attributes.

Harvest-ironman: heavy armature, and not its defensive secretions, protects a harvestman against a spider

Natural selection has caused prey species to evolve distinct defensive mechanisms. One of such mechanisms was the evolution of noxious or distasteful chemicals, which have appeared independently in a number of vertebrates and invertebrates. In detailed analyses of arthropod behaviour, scent gland secretions have consistently been shown to be responsible for repelling specific predators. Because using such chemicals is costly, animals with alternative cheaper defences are expected not to release such secretions when alternative options exist. In this study, we sought to determine the defensive mechanisms of the harvestman Discocyrtus invalidus, a heavy bodied species that bears a pair of repugnatorial glands. The spider Enoploctenus cyclothorax was used as the predator, and the cricket Gryllus sp. was used as a control. In a first set of experiments, the harvestmen were preyed upon significantly less than the crickets. In two other experiments, we found that harvestmen did not use their scent gland secretions to deter the predator. Moreover, results of a fourth experiment revealed that these spiders are not repelled by defensive secretions. Discocyrtus invalidus has a thick cuticle on the entire body: scanning electron micrographs revealed that only the mouth, the articulations of appendages and the tips of the legs are not covered by a hard integument. In a fifth experiment, we found that these spiders had difficulty piercing the harvestmen body. This is the first experimental evidence that a chemically defended arachnid does not use its scent gland secretions to repel a much larger predator but instead relies on its heavily built body. (c) 2010 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

Identification of new ozonation disinfection byproducts of 17 beta-estradiol and estrone in water

Estrogens are a class of micro-pollutants found in water at low concentrations (in the ng L(-1) range), but often sufficient to exert estrogenic effects due to their high estrogenic potency. Disinfection of waters containing estrogens through oxidative processes has been shown to lead to the formation of disinfection byproducts, which may also be estrogenic. The present work investigates the formation of disinfection byproducts of 17 beta-estradiol (E2) and estrone (E1) in the treatment of water with ozone. Experiments have been carried out at two different concentrations of the estrogens in ground water (100 ng L(-1) and 100 mu g L(-1)) and at varying ozone dosages (0-30 mg L(-1)). Detection of the estrogens and their disinfection byproducts in the water samples has been performed by means of ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) with a triple quadrupole (QqQ) and a quadrupole-time of flight (QqTOF) instrument. Both E2 and El have been found to form two main byproducts, with molecular mass (MM) 288 and 278 in the case of E2, and 286 and 276 in the case of El, following presumably the same reaction pathways. The E2 byproduct with MM 288 has been identified as 10epsilon-17beta-dihydroxy-1,4-estradieno-3-one (DEO), in agreement with previously published results. The molecular structures and the formation pathways of the other three newly identified byproducts have been suggested. These byproducts have been found to be formed at both high and low concentrations of the estrogens and to be persistent even after application of high ozone dosages. (C) 2011 Elsevier Ltd. All rights reserved.

Comparison of adsorbent films obtained by plasma polymerization of oxygenated organic compounds

Thin films obtained by plasma polymerization of ethyl ether, methyl or ethyl acetate, acetaldehyde, acetone and 2-propanol were compared. Infrared spectroscopy (FFIR), resistance to chemicals, contact angle measurements, X-ray photoelectron spectroscopy (XPS), optical and scanning electron microscopy (SEM), and quartz crystal microbalance (QCM) were carried out. For all films FTIR showed high intensity for polar bonds yet the films are not resistant to polar solvents. Contact angle measurements revealed hydrophilic and organophilic surfaces and XPS pointed out a high proportion of oxygenated bonds. All films showed good step coverage and peeling was significant only with acetone and 2-propanol. All films are adsorbent for organic compounds in a large scale of polarity but acetaldehyde and 2-propanol act like a selective membrane. Also, deposition of these films on hydrophobic substrates leads to island formation. A possible model to explain the results must consider the hydrogen bridge formation on 2-propanol and acetaldehyde films. Ethyl ether, ethyl and methyl acetate showed good characteristics for development of sensor and sample pretreatment using miniaturized devices. (C) 2007 Elsevier B.V. All rights reserved.

Cytotoxic and mutagenic evaluation of extracts from plant species of the Miconia genus and their influence on doxorubicin-induced mutagenicity: An in vitro analysis

The Miconia genus, a plant widely used for medicine, occurs in tropical America and its extracts and isolated compounds have demonstrated antibiotic, antitumoral, analgesic and antimalarial activities. However, no study concerning its genotoxicity has been conducted and it is necessary to determine its potential mutagenic effects to develop products and chemicals from these extracts. This study assessed the cytotoxicity, mutagenicity and the protective effects of methanolic extracts from Miconia species on Chinese hamster lung fibroblast cell cultures (V79). The cytotoxicity was evaluated using a clonogenic assay. Cultures exposed to the extract of Miconia albicans up to a concentration of 30 mu g/mL, M. cabucu up to 40 mu g/mL, M. albicans up to 40 mu g/mL and M. stenostachya up to 60 mu g/mL exhibited a cytotoxic effect on the cells. The clonogenic assay used three non-cytotoxic concentrations (5, 10 and 20 mu g/mL) to evaluate mutagenicity and antimutagenicity of the extracts. Cultures were treated with these three extract concentrations (mutagenicity test) or the extract associated with doxorubicin (DXR) (antimutagenicity test) in three protocols (pre-, simultaneous and post-treatments). Distilled water and DXR were used as negative and positive controls, respectively. In the micronucleus (MN) test, a significant reduction was observed in MN frequency in cultures treated with DXR and extracts compared to those receiving only DXR; a significant reduction was also observed for the presence of mutagenicity in all treatments. This study confirmed the safe use of Miconia extracts at the concentrations tested and reinforced the therapeutic properties previously described for Miconia species by showing their protective effects on doxorubicin-induced mutagenicity. (C) 2010 Elsevier GmbH. All rights reserved.