Ecotoxicological Effects Of Carbofuran And Oxidised Multiwalled Carbon Nanotubes On The Freshwater Fish Nile Tilapia: Nanotubes Enhance Pesticide Ecotoxicity.

The interactions of carbon nanotubes with pesticides, such as carbofuran, classical contaminants (e.g., pesticides, polyaromatic hydrocarbons, heavy metals, and dyes) and emerging contaminants, including endocrine disruptors, are critical components of the environmental risks of this important class of carbon-based nanomaterials. In this work, we studied the modulation of acute carbofuran toxicity to the freshwater fish Nile tilapia (Oreochromis niloticus) by nitric acid treated multiwalled carbon nanotubes, termed HNO3-MWCNT. Nitric acid oxidation is a common chemical method employed for the purification, functionalisation and aqueous dispersion of carbon nanotubes. HNO3-MWCNT were not toxic to Nile tilapia at concentrations ranging from 0.1 to 3.0 mg/L for exposure times of up to 96 h. After 24, 48, 72 and 96 h, the LC50 values of carbofuran were 4.0, 3.2, 3.0 and 2.4 mg/mL, respectively. To evaluate the influence of carbofuran-nanotube interactions on ecotoxicity, we exposed the Nile tilapia to different concentrations of carbofuran mixed together with a non-toxic concentration of HNO3-MWCNT (1.0 mg/L). After 24, 48, 72, and 96 h of exposure, the LC50 values of carbofuran plus nanotubes were 3.7, 1.6, 0.7 and 0.5 mg/L, respectively. These results demonstrate that HNO3-MWCNT potentiate the acute toxicity of carbofuran, leading to a more than five-fold increase in the LC50 values. Furthermore, the exposure of Nile tilapia to carbofuran plus nanotubes led to decreases in both oxygen consumption and swimming capacity compared to the control. These findings indicate that carbon nanotubes could act as pesticide carriers affecting fish survival, metabolism and behaviour.

Variabilidade espacial e sazonal da concentração de elementos-traço em sedimentos do sistema estuarino de Santos-Cubatão (SP)

Multi-element analyses of sediment samples from the Santos-Cubatão Estuarine System were carried out to investigate the spatial and seasonal variability of trace-element concentrations. The study area contains a rich mangrove ecosystem that is a habitat for tens of thousands of resident and migratory birds, some of them endangered globally. Enrichments of metals in fine-grained surface sediments are, in decreasing order, Hg, Mn, La, Ca, Sr, Cd, Zn, Pb, Ba, Cu, Cr, Fe, Nb, Y, Ni and Ga, relative to pre-industrial background levels. The maximum enrichment ranged from 49 (Hg) to 3.1 (Ga). Mercury concentrations were greater in the Cubatão river than in other sites, while the other elements showed greater concentrations in the Morrão river. Concentrations of Mn were significantly greater in winter and autumn than in summer and spring. However, other elements (e.g. Cd and Pb) showed the opposite, with greater concentrations in summer and spring. This study suggests that seasonal changes in physical and chemical conditions may affect the degree of sediment enrichment and therefore make the assessment of contamination difficult. Consequently, these processes need to be considered when assessing water quality and the potential contamination of biota.

Novos sorventes baseados em poli (metiloctilsiloxano) sobre sílica para uso em extração em fase sólida

This paper presents an easy and practical procedure to obtain silica-based C-8 type sorbents for use in solid-phase extraction. The materials are prepared by depositing poly(methyloctylsiloxane), PMOS, on the silica support. Two different treatments for immobilization were used: thermal treatment or gamma irradiation. Suitable recoveries were obtained after pre-concentration of dilute solutions, at the ng/L level, of a mixture of pesticides, indicating the good performance of the materials.

Contaminação de produtos de higiene e cosméticos por n-nitrosaminas

N-nitrosamines are carcinogenic compounds that have been found during the last three decades in a variety of consumer products, including cosmetic and personal care products, and their raw materials. These compounds are formed from amine precursors and nitrosating agents present in the formulations. This paper reviews the formation and occurrence of N-nitrosamines in cosmetic products, as well as presents considerations about analytical, toxicological and regulatory aspects.

Sistema limpo em linha para extração em fase sólida de contaminantes emergentes em águas naturais

A solid-phase in-line extraction system for water samples containing low levels of emerging contaminants is described. The system was specially developed for large volume samples (up to 4 L) using commercial solid-phase extraction (SPE) cartridges. Four sets containing PTFE-made connectors, brass adapters and ball valves were used to fit SPE cartridges and sample bottles to a 4-port manifold attached to a 20 L carboy. A lab-made vacuum device was connected to the manifold cap. The apparatus is robust and less expensive than the typical available system. Its also provides less experimental handling, avoiding cross contamination and sample losses.

Alteração da atividade enzimática em organismos aquáticos por poluentes de origem agrícola: uma abordagem geral e sobre a suscetibilidade da fosfatase ácida

The input of agrochemicals in the aquatic compartment can results in biochemical injuries for living organisms. In this context, the knowledge of alterations of enzymatic activities due the presence of agriculture pollutants contributes for the elucidation of the mechanisms of toxicity, implementation of economic methods for monitoring purposes and establishment of maximum allowed concentrations. In the present work, the above considerations are discussed, and data concerning changes in enzymatic function by pesticides and fertilizer contaminants are reviewed. Also, we focused on the acid phosphatase due its susceptibility to several pollutants and diversity in cellular functions.

Modelos de transferência de metal pesado na cana-de-açúcar adubada com composto de lixo urbano

The research approaches recycling of urban waste compost (UWC) as an alternative fertilizer for sugarcane crop and as a social and environmental solution to the solids residuals growth in urban centers. A mathematical model was used in order to know the metal dynamics as decision support tool, aiming to establish of criteria and procedures for UWC's safe use, limited by the amount of heavy metal. A compartmental model was developed from experimental data in controlled conditions and partially checked with field data. This model described the heavy metal transference in the system soil-root-aerial portion of sugarcane plants and concluded that nickel was metal to be concern, since it takes approximately three years to be attenuated in the soil, reaching the aerial portions of the plant at high concentrations. Regarding factors such as clay content, oxide level and soil pH, it was observed that for soil with higher buffering capacity, the transfer of the majority of the metals was slower. This model may become an important tool for the attainment of laws regarding the UWC use, aiming to reduce environment contamination the waste accumulation and production costs.

Filtros de areia aplicados à irrigação localizada: teoria e prática

The application of sand filters in localized irrigation systems is recommended in the presence of organic and algae contamination. The proper design and maintenance of these equipments are essential to assure an effective water quality control, in order to reduce the emitters clogging, to keep its water application uniformity, and to prevent increasing in the system operation costs. Despite the existence of some references about design, operation and maintenance of these filters, they are dispersed, with not enough details to guarantee the optimization of its hydraulics structure design and the proper selection of porous media to be used. Therefore, the objective of this work was to report a current literature review, relating practical information with scientific knowledge. The content of this review would help to induce and intensify the research on this subject and to contribute so the operational functions for the equipment are reached. It is also expected to assist the improvement of the filtration and flushing processes in the agricultural irrigation and the development of original design procedures and the rational use of these devices.

Thermolysed and active yeast to reduce the toxicity of aflatoxin

Aflatoxins are hepatotoxic metabolites produced by Aspergillus flavus and A. parasiticus on a number of agricultural commodities. This research was carried out to evaluate the ability of thermolysed and active Saccharomyces cerevisiae to attenuate liver damage caused by aflatoxin. Diets were prepared containing 0 aflatoxin; 400 mug kg-1 aflatoxin; 400 mug kg-1 aflatoxin plus 1% of dehydrated active yeast, and 400 mug kg-1 aflatoxin plus 1% of thermolysed yeast. A bioassay with Wistar rats was conducted for 28 days, and body organs were weighted and analyses of the liver tissue of the animals were performed. The relative weight of heart, kidneys and liver from animals submitted to the different treatments did not show any difference, and liver tissue of animals feeding on the aflatoxin-free diet was adopted as a toxicity-free pattern. Hepatic tissue of animals feeding on diets containing 400 mug kg-1 aflatoxin or the diet supplemented with 1% thermolysed yeast showed clear signs of toxicity and damage. Hepatic tissue of animals feeding on the diet containing 1% of dehydrated active yeast showed less toxicity signs and damage than those receiving the diet containing 400 mug kg-1 aflatoxin. Active, dehydrated yeast had the ability to reduce toxic effects caused by aflatoxin, but thermolysed yeast was not able to alleviate the effects of aflatoxin toxicity.

Qualidade pós-colheita de caqui 'fuyu' com utilização de diferentes concentrações de cobertura comestível

One of the main objectives of applying edible coatings on fruits surface is to create a protective film to reduce weight loss due to evaporation and transpiration and also to decrease the risk of fruit rot caused by environmental contamination, in order to improve the visual aspect. Therefore, it is possible to increase shelf life, and decrease post harvest losses. Persimmon is a much appreciated fruit, with high potential for export, but sensitive to handling and storage. This study aimed to evaluate the effect of applying the edible coating Megh Wax ECF-124 (18% of active composts, consisting of emulsion of carnauba wax, anionic surfactant, preservative and water) produced by Megh Industry and Commerce Ltda in three different concentrations (25, 50 and 100%) on post harvest quality of 'Fuyu' persimmon stored for 14 days. The attributes evaluated for quality were: firmness, pH, acidity, soluble solids, weight loss and color. The results showed that application of carnauba wax in different concentrations was effective on decreasing weight loss of persimmon cv. Fuyu and maintenance of color aspects. Treatment at lower concentration, 25%, showed lower rate of discharge, but high concentrations showed lower values of mass loss. Carnauba wax application showed a high potential for use on postharvest conservation, and can be applied together with other technologies, helping to maintain quality for export.

Hidrocarbonetos aromáticos policíclicos em margarina, creme vegetal e maionese

Polycyclic aromatic hydrocarbons (PAHs) are a group of compounds that have been the subject of much concern due to their toxic potential. In this study, margarine?s, vegetable cream and mayonnaise available on the Brazilian market were analyzed for pyrene, chrysene, benzo(a)pyrene, benzo(b)fluoranthene and dibenzo(a,h)anthracene. The analytical methodology involved liquid-liquid extraction, clean-up on silica gel column and determination by high performance liquid chromatography using fluorescence detector. Variable levels of contamination were found within differents brands of the same product and within differents batches of the same brand. The total PAH content was in the range of 4.1 to 7.1mug/kg in vegetable cream, 1.7 to 3.9mug/kg in margarine and 1.0 to 21.7mug/kg in mayonnaise. In general the products which according to the label contain corn oil showed the highest levels of contamination. Based on these results and on the importance of fat, oils and derived products for the intake of PAHs, it is recommended that producers of margarine, vegetable creams and mayonnaise start to control the contamination of the vegetable oils used in the elaboration of these products, in order to reduce the exposure of consumers to excessive amounts of potentially carcinogenic compounds.

Qualidade de vida e avaliação fisica em intoxicados por mercurio : estudo observacional transversal descritivo

Universidade Estadual de Campinas . Faculdade de Educação Física

Bonding agent underneath sealant: shear bond strength to oil-contaminated

This study evaluated in vitro the shear bond strength of a resin-based pit-and-fissure sealant (Fluroshield - F) associated with either an ethanol-based (Adper Single Bond 2 - SB) or an acetone-based (Prime & Bond - PB) adhesive system under conditions of oil contamination. Mesial and distal enamel surfaces from 30 sound third molars were randomly assigned to 2 groups (n=30): I - no oil contamination; II - oil contamination. Contamination (0.25 mL during 10 s) was performed after 37% phosphoric acid etching with an air/oil spray. The specimens were randomly assigned to subgroups, according to the bonding protocol adopted: subgroup A - F was applied to enamel without an intermediate bonding agent layer; In subgroups B and C, SB and PB, respectively, were applied, light-cured, and then F was applied and light-cured. Shear bond strength was tested at a crosshead speed of 0.5 mm/min in a universal testing machine. Means (± SD) in MPa were: IA-11.28 (±1.84); IIA-12.02 (±1.15); IB-9.73 (±2.38); IIB-9.62 (±2.29); IC-28.30 (±1.63); and IIC-25.50 (±1.91). It may be concluded that the oil contamination affected negatively the sealant bonding to enamel and the acetone-based adhesive system (PB) layer applied underneath the sealant was able to prevent its deleterious effects to adhesion.

Effect of phosphate-bonded investments on titanium reaction layer and crown fit

This study analyzed the reaction layer and measured the marginal crown fit of cast titanium applied to different phosphate-bonded investments, prepared under the following conditions (liquid concentration/casting temperature): Rema Exakt (RE) - 100%/237°C, 75%/287°C, Castorit Super C (CS)-100%/70°C, 75%/141°C and Rematitan Plus (RP)- 100%/430°C (special to titanium cast, as the control group). The reaction layer was studied using the Vickers hardness test, and analyzed by two way ANOVA and Tukey's HSD tests (α = 0.05). Digital photographs were taken of the crowns seated on the die, the misfit was measured using an image analysis system and One-way ANOVA, and Tukey's test was applied (α = 0.05). The hardness decreased from the surface (601.17 VHN) to 150 μm (204.03 VHN). The group CS 75%/141°C presented higher hardness than the other groups, revealing higher surface contamination, but there were no differences among the groups at measurements deeper than 150 μm. The castings made with CS - 100%/70°C presented the lowest levels of marginal misfit, followed by RE -100%/237°C. The conventional investments CS (100%) and RE (100%) showed better marginal fit than RP, but the CS (75%) had higher surface contamination.

Antimicrobial efficacy of chemical disinfectants on contaminated full metal crowns

Prosthetic restorations that have been tried in the patient's mouth are potential sources of infection. In order to avoid cross-infection, protocols for infection control should be established in dental office and laboratory. This study evaluated the antimicrobial efficacy of disinfectants on full metal crowns contaminated with microorganisms. Full crowns cast in a Ni-Cr alloy were assigned to one control group (n=6) and 5 experimental groups (n=18). The crowns were placed in flat-bottom glass balloons and were autoclaved. A microbial suspension of each type of strain - S. aureus, P. aeruginosa, S. mutans, E. faecalis and C. albicans- was aseptically added to each experimental group, the crowns being allowed for contamination during 30 min. The contaminated specimens were placed into recipients with the chemical disinfectants (1% and 2% sodium hypochlorite and 2% glutaraldehyde) for 5, 10 and 15 min. Thereafter, the crowns were placed into tubes containing different broths and incubated at 35ºC. The control specimens were contaminated, immersed in distilled water for 20 min and cultured in Thioglycollate broth at 35ºC. Microbial growth assay was performed by qualitative visual examination after 48 h, 7 and 12 days. Microbial growth was noticed only in the control group. In the experimental groups, turbidity of the broths was not observed, regardless of the strains and immersion intervals, thus indicating absence of microbial growth. In conclusion, all chemical disinfectants were effective in preventing microbial growth onto full metal crowns.