Franz Zirena Vilca

Microcystin-LR bioaccumulation and depuration kinetics in lettuce and arugula: Human health risk assessment

Microcystin-LR (MC-LR) is one of the most toxic and common microcystins (MCs) variant found in aquatic ecosystems. Little is known about the possibility of recovering microcystins contaminated agricultural crops. The objectives of this study were to determine the bioaccumulation and depuration kinetics of MC-LR in leaf tissues of lettuce and arugula, and estimate the total daily intake (ToDI) of MC-LR via contaminated vegetables by humans. Arugula and lettuce were irrigated with contaminated water having 5 and 10μgL(-1) of MC-LR for 7days (bioaccumulation), and subsequently, with uncontaminated water for 7days (depuration). Quantification of MC-LR was performed by LC-MS/MS. The one-compartment biokinetic model was employed for MC-LR bioaccumulation and depuration data analysis. MC-LR was only accumulated in lettuce. After 7days of irrigation with uncontaminated water, over 25% of accumulated MC-LR was still retained in leaf tissues of plants treated with 10μgL(-1) MC-LR. Total daily toxin intake by adult consumers (60kg-bw) exceeded the 0.04μgMC-LRkg(-1) limit recommended by WHO. Bioaccumulation was found to be linearly proportional to the exposure concentration of the toxin, increasing over time; and estimated to become saturated after 30days of uninterrupted exposure. On the other hand, MC-LR depuration was less efficient at higher exposure concentrations. This is because biokinetic half-life calculations gave 2.9 and 3.7days for 5 and 10μgL(-1) MC-LR treatments, which means 29-37days are required to eliminate the toxin. For the first time, our results demonstrated the possibility of MC-LR decontamination of lettuce plants.

Monitoring of Pesticide Residues in Surface and Subsurface Waters, Sediments, and Fish in Center-Pivot Irrigation Areas

In this study, the monitoring of pesticide residues, which show potential for environmental contamination, in center-pivot irrigated areas in the Brazilian cerrado, was performed. The pesticides monitored were acephate, atrazine, azoxystrobin, buprofezin, carbofuran, cyproconazole, chlorpyrifos, difenoconazole, diuron, imidacloprid, malathion, methamidophos, metolachlor, metribuzin, monocrotophos, monuron, thiamethoxam, and triazophos. Surface water samples were collected upstream and downstream of Tijunqueiro dam. The subsurface water in piezometric wells was drilled in the surroundings of the irrigated area; fish and sediment were collected in the dam. The technique of solid phase extraction (SPE) was used for the extraction of water samples, the matrix solid phase dispersion (MSPD) for the sediment samples and QuEChERS (quick, easy, cheap, effective, rugged and safe) for the fish samples. The multiresidue methods used were accurate and precise for most pesticides monitored by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Atrazine was detected in two of the subsurface water samples.

GLIFOSATO EN CUERPOS HÍDRICOS: PROBLEMA AMBIENTAL

La necesidad de incrementar la produccion de alimentos en el mundo esta haciendo con que los sistemas agricolas esten siendo mas extensivos, caracterizandose por sistemas de produccion a gran escala, donde el control de plagas y de malezas se hace mediante la aplicacion de productos quimicos. Muchos de los cuales son parte fundamental de un paquete tecnologico como es el caso del glifosato en el cultivo de soja transgenica; dada su alta eficacia en el control de malezas. Sin embargo, residuos de este producto puede contaminar varios compartimientos del ecosistema, siendo el ecosistema acuatico el mas perjudicado. Por lo que, seran abordados varios efectos adversos de este compuesto en organismos que habitan estos ecosistemas. ABSTRACT The need to increase food production in the world is creating more extensive agricultural systems, featured by large scales of production, where the control of pest and weeds are made through the application of chemical products. Many of them belong to a technological package that is the case of glyphosate in the cultivation of transgenic soy; given its high efficiency in the control of invasive plants, however, residues of this product can contaminate several compartments of the ecosystem, the aquatic ecosystem being the most affected. Therefore, several adverse effects of this compound will be addressed to organisms that inhabit this ecosystem. Key words: Polluted water, pesticides, environmental impact, ecological risk.

Concentrations of polycyclic aromatic hydrocarbons in liver samples of juvenile green sea turtles from Brazil: Can these compounds play a role in the development of fibropapillomatosis?

Fibropapillomatosis (FP) poses a significant threat to the conservation of green sea turtles (Chelonia mydas). Polycyclic aromatic hydrocarbons-PAHs are considered mutagenic, carcinogenic and toxic, and can act as cofactor of this disease. In order to evaluate possible differences between green sea turtles with and without FP, we monitored 15 PAHs in liver samples of 44 specimens (24 with FP) captured in Brazil. We detected eight PAHs and quantified phenanthrene in all green sea turtles with FP. Specimens without FP presented lower values than the tumored ones (1.48 ng g-1 and 17.35 ng g-1, respectively; p < 0.0001). There were no significant differences between tumored and non-tumored specimens, among studied areas, or Southwest Atlantic Fibropapillomatosis Score. Even though we found higher concentrations in the liver samples of green sea turtles with FP, further studies are necessary to confirm if these pollutants are involved in the pathogenesis of the disease.

Quechers Approach for the Determination of Seven Pesticide Residues in Brazilian Honey Samples Using GC-µECD

Honey is an important food widely used by people around the world. It can contain agrochemical residues as a result of the use of these products in agriculture. QuEChERS method was used for the determination of seven pesticide residues (chlorothalonil, heptachlor, captan, α-endosulfan, β-endosulfan, endosulfan sulfate and dieldrin) in 25 Brazilian honey samples from different regions. Extraction was carried out through the use of 1% acetic acid-ethyl acetate solvent with MgSO4 and CH3COONa, followed by dSPE cleanup with PSA sorbent. The analyses were carried out with GC-µECD. The chromatographic signal showed good linearity with correlation coefficient ≥ 0.99 and the LOQs for the pesticides studied varied between 0.007 to 0.05 mg kg -1 . The method was validated using a blank sample of honey spiked at three fortification levels (0.07, 0.2 and 0.4 mg kg -1 ). The recoveries for the seven compounds ranged from 75% to 119%, and relative standard deviations were ≤ 26%. Five of the 25 honey samples analyzed contained pesticide residues, with a maximum concentration of 0.026 mg kg -1 for α-endosulfan. From the five contaminated samples, four were from non-agricultural areas, which indicated environmental contamination at these sites. The QuEChERS approach was successfully employed for the GC-µECD analyses of the seven studied pesticides in honey samples.