792 resultados para ENVIRONMENTAL SCIENCES


Relevância:

60.00% 60.00%

Publicador:

Resumo:

The impact of particle emissions by biomass burning is increasing throughout the world. We explored the toxicity of particulate matter produced by sugar cane burning and compared these effects with equivalent mass of traffic-derived particles. For this purpose, BALB/c mice received a single intranasal instillation of either distilled water (C) or total suspended particles (15 mu g) from an urban area (SP group) or biomass burning-derived particles (Bio group). Lung mechanical parameters (total, resistive and viscoelastic pressures, static elastance, and elastic component of viscoelasticity) and histology were analyzed 24h after instillation. Trace elements and polycyclic aromatic hydrocarbons (PAHs) metabolites of the two sources of particles were determined. All mechanical parameters increased similarly in both pollution groups compared with control, except airway resistive pressure, which increased only in Bio. Both exposed groups showed significantly higher fraction area of alveolar collapse, and influx of polymorphonuclear cells in lung parenchyma than C. The composition analysis of total suspended particles showed higher concentrations of PAHs and lower concentration of metals in traffic than in biomass burning-derived particles. In conclusion, we demonstrated that a single low dose of ambient particles, produced by traffic and sugar cane burning, induced significant alterations in pulmonary mechanics and lung histology in mice. Parenchymal changes were similar after exposure to both particle sources, whereas airway mechanics was more affected by biomass-derived particles. Our results indicate that biomass particles were at least as toxic as those produced by traffic. (C) 2008 Elsevier Inc. All rights reserved.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

The Canoparmelia texana epiphytic lichenized fungi was used to monitor atmospheric pollution in the Sao Paulo metropolitan region, SP, Brazil. The cluster analysis applied to the element concentration values confirmed the site groups of different levels of pollution due to industrial and vehicular emissions. In the distribution maps of element concentrations, higher concentrations of Ba and Mn were observed in the vicinity of industries and of a petrochemical complex. The highest concentration of Co found in lichens from the Sao Miguel Paulista site is due to the emissions from a metallurgical processing plant that produces this element. For Br and Zn, the highest concentrations could be associated both to vehicular and industrial emissions. Exploratory analyses revealed that the accumulation of toxic elements in C. texana may be of use in evaluating the human risk of cardiopulmonary mortality due to prolonged exposure to ambient levels of air pollution. (c) 2007 Elsevier Ltd. All rights reserved.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

In this study, we tested the influence of ambient air pollution on different phases of development of adult mice. With respect to adult weight, the animals that had spent their in utero period exposed to pollution showed less weight gain over their lifetime, as well as lower activity levels of the antioxidant enzymes catalase, superoxide dismutase (SOD) and glutathione peroxidase (GPx). Our study suggests that contact with atmospheric pollutants during the foetal period produces important changes on enzymatic erythrocyte antioxidant defense and weight in adult mice. (C) 2011 Elsevier B.V. All rights reserved.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

In Brazil, sugarcane fields are often burned to facilitate manual harvesting, and this burning causes environmental pollution from the large amounts of soot released into the atmosphere. This material contains numerous organic compounds such as PAHs. In this study, the concentrations of PAHs in two particulate-matter fractions (PM(2.5) and PM(10)) in the city of Araraquara (SE Brazil, with around 200,000 inhabitants and surrounded by sugarcane plantations) were determined during the sugarcane harvest (HV) and non-harvest (NHV) seasons in 2008 and 2009. The sampling strategy included four campaigns, with 60 samples in the NHV season and 220 samples in the HV season. The PM(2.5) and PM(10) fractions were collected using a dichotomous sampler (10 L min(-1), 24 h) with Teflon (TM) filters. The filter sets were extracted (ultrasonic bath with hexane/acetone (1:1 v/v)) and analyzed by HPLC/Fluorescence. The median concentration for total PAHs (PM(2.5) in 2009) was 0.99 ng m(-3) (NHV) and 3.3 ng m(-3) (HV). In the HV season, the total concentration of carcinogenic PAHs (benz(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, and benzo(a)pyrene) was 5 times higher than in the NHV season. B(a)P median concentrations were 0.017 ng m(-3) and 0.12 ng m(-3) for the NHV and HV seasons, respectively. The potential cancer risk associated with exposure through inhalation of these compounds was estimated based on the benzo[a]pyrene toxic equivalence (BaP(eq)), where the overall toxicity of a PAR mixture is defined by the concentration of each compound multiplied by its relative toxic equivalence factor (TEF). BaP(eq) median (2008 and 2009 years) ranged between 0.65 and 1.0 ng m(-3) and 1.2-1.4 ng m(-3) for the NHV and HV seasons, respectively. Considering that the maximum permissible BaPeq in ambient air is 1 ng m(-3), related to the increased carcinogenic risk, our data suggest that the level of human exposure to PAHs in cities surrounded by sugarcane crops where the burning process is used is cause for concern. (C) 2010 Published by Elsevier Ltd.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Objectives: The purpose of this study was to explore the clinical relevance of chronic exposure to ambient levels of traffic derived air pollution on the ocular surface. Methods: A panel study involving 55 volunteers was carried out in Sao Paulo, Brazil. We measured the mean individual levels of nitrogen dioxide (NO(2)) exposure for 7 days. All subjects answered the Ocular Symptom Disease Index (OSDI) and a symptoms inventory. Subsequently, subjects underwent Schirmer I test, biomicroscopy, vital staining and tear breakup time (TOUT) assessment. Subject`s mean daily exposure to NO(2) was categorized in quartiles. Statistical analysis was performed using one-way ANOVA, Tukey HSD and Chi-Square tests. Results: A dose-response pattern was detected between OSDI scores and NO(2) quartiles (p < 0.05). There was a significant association between NO(2) quartiles and reported ocular irritation (X(2) = 9.2, p < 0.05) and a significant negative association between TBUT and NO(2) exposure (p < 0.05, R = -0.316. Spearman`s correlation). There was a significant increase in the frequency of meibomitis in subjects exposed to higher levels of NO(2) (p < 0.05). Conclusions: Subjects exposed to higher levels of traffic derived air pollution reported more ocular discomfort symptoms and presented greater tear film instability, suggesting that the ocular discomfort symptoms and tear breakup time could be used as convenient bioindicators of the adverse health effects of traffic derived air pollution exposure. (C) 2010 Elsevier Inc. All rights reserved.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

We evaluated short-term effects of sidestream cigarette smoke (SSCS) exposure on baroreflex function in spontaneously hypertensive rats (SHR) and Wistar Kyoto (WKY) normotensive rats. Rats were exposed to SSCS during three weeks, 180min, five days per week, in a concentration of carbon monoxide (CO) between 100 and 300ppm. We observed that SSCS exposure increased tachycardic peak and heart rate range while it attenuated bradycardic reflex in WKY. In respect to SHR, SSCS also increased tachycardic peak. Taken together, our data suggests that three weeks of exposure to SSCS affects the sympathetic and parasympathetic component of the baroreflex in normotensive WKY while it tended to affect the sympathetic component in SHR.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Wastewater control at storage terminals of liquid chemical products in bulk is very difficult because of the variety of products handled in the facilities generating effluents of variable composition. The main objective of this work was to verify if the Vibrio fischeri acute toxicity test could be routinely included in the wastewater management of those facilities along with physical and chemical analysis in order to evaluate and improve the quality of the generated effluents. The study was performed in two phases before and after the implementation of better operational practices/treatment technologies. Chemical oxygen demand (COD) and toxicity of treated effluents did not correlate showing that effluents with low COD contain toxic substances and non-biodegradable organic matter, which may be not degraded when discharged into the aquatic environment. Segregation of influents or pre-treatment based on toxicity results and biodegradability index were implemented in the facilities generating significant improvements in the quality of final effluents with reduction of Biochemical oxygen demand (BOD) and toxicity. The integration of physical and chemical analysis with the V.fischeri toxicity test turned out to be an excellent tool for wastewater management in chemical terminals allowing rapid decision making for pollution control and prevention measures. Reuse of rain water was also proposed and when implemented by the facilities resulted in economical and environmental benefits. (C) 2010 Elsevier B.V. All rights reserved.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Objective: Biofuel from sugarcane is widely produced in developing countries and is a clean and renewable alternative source of energy. However, sugarcane harvesting is mostly performed after biomass burning. The aim of this study was to evaluate the effects of harvesting after biomass burning on nasal mucociliary clearance and the nasal mucus properties of farm workers. Methods: Twenty seven sugarcane workers (21-45 years old) were evaluated at the end of two successive time-periods: first at the end of a 6-month harvesting period (harvesting), and then at the end of a 3-month period without harvesting (non-harvesting). Nasal mucociliary clearance was evaluated by the saccharine transit test, and mucus properties were analyzed using in vitro mucus contact angle and mucus transportability by sneeze. Arterial blood pressure, heart rate, respiratory rate, pulse oximetry, body temperature, associated illness, and exhaled carbon monoxide were registered. Results: Data are presented as mean values (95% confidence interval). The multivariate model analysis adjusted for age, body-mass index, smoking status and years of working with this agricultural practice showed that harvesting yielded prolonged saccharine transit test in 7.83 min (1.88-13.78), increased mucus contact angle in 8.68 degrees (3.18-14.17) and decreased transportability by sneeze in 32.12 mm (-44.83 to -19.42) compared with the non-harvesting period. No significant differences were detected in any of the clinical parameter at either time-period. Conclusion: Sugarcane harvesting after biomass burning negatively affects the first barrier of the respiratory system in farm workers by impairing nasal mucociliary clearance and inducing abnormal mucus properties. (C) 2011 Elsevier Inc. All rights reserved.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Polymorphic variations of several genes associated with dietary effects and exposure to environmental carcinogens may influence susceptibility to leukemia development. The objective of the present study was to evaluate the effect of the polymorphisms of debrisoquine hydroxylase (CYP2D6), epoxide hydrolase (EPHX1), myeloperoxidase (MPO), and quinone-oxoreductase (NQO1), which have been implicated in xenobiotic metabolism, on the risk of childhood acute lymphoblastic leukemia (ALL). We evaluated the frequency of polymorphisms in the CYP2D6 (*3 and *4), EPHX1 (*2 and *3), MPO (*2), and NQO1 (*2) genes in 206 patients with childhood ALL and in 364 healthy individuals matched for age and gender from a Brazilian population separated by ethnicity (European ancestry and African ancestry), using the PCR-RFLP method. The CYP2D6 polymorphism variants were associated with an increased risk of ALL. The EPHX1, NQO1, and MPO variant genotypes were significantly associated with a reduced risk of childhood ALL. A significantly stronger protective effect is observed when the EPHX1, NQO1, and MPO variant genotypes are combined suggesting that, CYP2D6 polymorphisms may play a role in the susceptibility to pediatric ALL, whereas the EPHX1, NQO1, and MPO polymorphisms might have a protective function against leukemogenesis. Environ. Mal. Mulagen. 51:48-56, 2010. (C) 2009 Wiley-Liss, Inc.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

The purpose of this study was to determine the concentrations of aluminum (Al) and other metals in water samples from elderly people`s houses and retirement homes. Forty-six duplicate water samples from kitchen taps were collected in Ribeiro Preto/SP, Brazil. Metal levels were measured by atomic absorption spectrophotometer. Aluminum concentration exceeded the maximum allowed values in 26% of samples according to the Decree 518/2004 of the Brazilian Health Ministry. It was noted that 11% of elderly living at monitored houses, as well as 19% living at retirement homes presented Alzheimer disease diagnostic. These results suggest taking into account Al risks among vulnerable elderly population groups.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Wild canids are under many pressures, including habitat loss, fragmentation and disease. The current lack of information on the status of wildlife health may hamper conservation efforts in Brazil. In this paper, we examined the prevalence of canine pathogens in 21 free-ranging wild canids, comprising 12 Cerdocyon thous (crab-eating fox), 7 Chrysocyon brachyurus (maned wolf), 2 Lycalopex vetulus (hoary fox), and 70 non-vaccinated domestic dogs from the Serra do Cip National Park area, Southeast Brazil. For wild canids, seroprevalence of antibodies to canine parvovirus, canine adenovirus, canine coronavirus and Toxoplasma gondii was 100 (21/21), 33 (7/21), 5 (1/19) and 68 (13/19) percent, respectively. Antibodies against canine distemper virus, Neospora caninum or Babesia spp. were not found. We tested domestic dogs for antibodies to canine parvovirus, canine distemper virus and Babesia spp., and seroprevalences were 59 (41/70), 66 (46/70), and 42 (40/70) percent, respectively, with significantly higher prevalence in domestic dogs for CDV (P < 0.001) and Babesia spp. (P = 0.002), and in wild canids for CPV (P < 0.001). We report for the first time evidence of exposure to canine coronavirus in wild hoary foxes, and Platynossomun sp. infection in wild maned wolves. Maned wolves are more exposed to helminths than crab-eating foxes, with a higher prevalence of Trichuridae and Ancylostomidae in the area. The most common ectoparasites were Amblyomma cajennense, A. tigrinum, and Pulex irritans. Such data is useful information on infectious diseases of Brazilian wild canids, revealing pathogens as a threat to wild canids in the area. Control measures are discussed.

Relevância:

60.00% 60.00%

Publicador:

Resumo:

Synthetic type II pyrethroid insecticides, such as cyhalothrin at certain dosage levels, simultaneously induce stress-like symptoms and innate immunosuppressive effects in laboratory animals. The present study was designed to further analyze the stress-like effects induced by cyhalotrin and also investigate the role of Hypothalamus-Hypophysis-Adrenal (HHA) axis and Sympathetic Nervous Systems (SNS) and their effects on macrophage activity of rats. Results showed that cyhalothrin treatment (3.0 mg/kg/day. for 7 days) increased corticosterone serum levels and c-fos immunoreactivity at the paraventricular nucleus of the hypothalamus (PVN) but induced no changes in c-fos expression at the basolateral amygdala (BLA). Both areas were related to HHA axis and SNS activations by stress. Further analysis showed that adrenalectomy partially abrogated the suppression effects of cyhalothrin on macrophage activity and that 6-OHDA-induced peripheral symphatectyomy had no effects on this innate immune cell activity. The present observed data support and reinforce the notion that cyhalotrin at this treatment schedule induces stress-like symptoms and suggest that other factors, beyond indirect neuroadaptative responses, are necessary for the suppression effects of insecticide on innate immune response. (C) 2008 Elsevier B.V. All rights reserved.