Removal of fipronil by advanced oxidative processes using sulfite activated by cobalt immobilized on silica.

Sulfite auto-oxidation catalyzed by cobalt complexed with ammonia deposited on silica (CoNSi) was used to generate sulfate radicals. The material was characterized by ATR-FTIR, suggesting that the silica structure did not change, and SEM-EDS, indicating an uniform dispersion of cobalt across the material surface according with XRD results. BET analysis provided information on a mesoporous material (type IV isotherm) with regular morphology (H1 hysteresis). The DSC analysis showed that CoNSi is thermally stable under the studied conditions. Quantitative analysis of Fipronil (FIP) was performed by HPLC-DAD, where the applied method was selective and linear. The Box-Behnken experimental design (BBD) method was used to define the best condition for removing the analyte in water. It was found that in 60 min, 76% removal of 1.8 mg L-1 of FIP was reached by adding 0.30 g of the material and 0.30 g of the sulfite in a solution under stirring, aeration, pH 8.0, and room temperature and protected from radiation. However, analysis of cobalt leaching into the solution by FAAS showed a small amount of the metal (0.44 mg L-1) informing that the synthesis of the material must be improved.

Mutagenic activity of airborne particulate matter (PM10) in a sugarcane farming area (Araraquara city, southeast Brazil).

Brazil contains 25% of the total land planted with sugarcane in the world and is thus one of the major producers. The annual burning of sugarcane fields prior to harvesting emits huge amounts of pyrogenic particles. Biomass burning is an important primary and secondary source of aerosol particles. The presence of carbonaceous particles in the inhalable size range makes it important to study this fraction in view of the possible effects on human health and the climate. In this study, the mutagenic activity associated with inhalable airborne particulate matter (PM(10)) collected on air filters in a sugarcane-growing area near the city of Araraquara (SE Brazil) was determined. The extracts were dissolved in dimethylsulfoxide and tested for mutagenicity by the Ames plate incorporation test with Salmonella typhimurium YG1024 in the presence and absence of the S9 mixture. To assess the association between mutagenicity and PM(10), samples were collected in sugarcane harvesting and non-harvesting periods of the year. Significant mutagenicity was detected in organic solvent extracts of all samples, with differences between the two periods. The highest values of mutagenic potency (13.45 and 5.72 revertants/m(3) of air in the absence and presence of the S9 mixture, respectively) were observed during the harvest. In this period, a Teflon™-coated glass-fiber air filter trapped 67.0 µg of particulate matter per m(3) of air. In the non-harvest period, on the same type of filter, only 20.9 µg of particulate matter was found per m(3). The mutagenic potencies at this time were 1.30 and 1.04 revertants/m(3) of air, in the absence and presence of the S9 mixture, respectively. Period, concentration of PM(10) and mutagenicity were associated with each other. For routine monitoring of mutagenicity in the atmosphere, the use of YG1024 tester strain without metabolic activation (S9) is recommended.

Effects of genetic polymorphisms CYP1A1, GSTM1, GSTT1 and GSTP1 on urinary 1-hydroxypyrene levels in sugarcane workers.

Sugarcane workers in Brazil are exposed to various genotoxic compounds, including polycyclic aromatic hydrocarbons (PAHs), derived from an incomplete combustion process of burnt sugarcane fields. The effects of the occupational exposure to sugarcane fields burning were measured in urine samples of sugarcane workers from the northwest of the State of São Paulo when exposed (harvesting) and when non-exposed (non-harvesting). The urinary levels of 1-hydroxypyrene (1-OHP) and the influence of the genetic polymorphisms CYP1A1, GSTM1, GSTT1 and GSTP1 were evaluated. Our results showed that the 1-OHP levels were significantly higher (P<0.0000) in the exposed sugarcane workers (0.318 mumol mol(-1) creatinine) than in the non-exposed workers (0.035 mumol mol(-1) creatinine). In an unvaried analysis, no influence regarding the polymorphisms was observed. However, multivariate regression analysis showed that the CYP1A1()4 polymorphism in the exposed group, and age and the GSTP1 polymorphism in the non-exposed group significantly influenced urinary 1-OHP excretion levels (P<0.10). The same group of sugarcane workers was significantly more exposed to PAHs during the harvesting period than during the non-harvesting period.