The evaluation of the potential ecotoxicity of pyroligneous acid obtained from fast pyrolysis.

Pyroligneous acid (PA) is a by-product of bio-oil, which is obtained by pyrolysis of the wood. This product has been tested for use in several areas, such as agriculture, as a promising green herbicide; however, there are few scientific data regarding its environmental impacts. For this study, an ecotoxicity testing battery, composed of Daphnia magna acute toxicity test, Allium cepa test and in vitro Comet assay with the rainbow trout gonad-2 cell fish line (RTG-2) were used to evaluate the acute toxicity and genotoxicity of PA obtained from fast pyrolysis of eucalyptus wood fines. The PA presented acute toxicity to D. magna (microcrustacea) with EC50 of 26.12 mg/L, and inhibited the seed germination (EC50 5.556 g/L) and root development (EC50 3.436 g/L) of A. cepa (higher plant). No signs of genotoxicity (chromosomal aberrations and micronuclei in A. cepa and primary DNA lesions in RTG-2 cells) were detected to this product. The acute toxicity and absence of genotoxicity may relate to the molecules found in the PA, being the phenolic fraction the key chemical candidate responsible for the toxicity observed. In addition, daphnids seem to be more sensitivity to the toxicity of PA than higher plants based on their EC50 values. This first ecotoxicological evaluation of PA from fast pyrolysis pointed out the need of determining environmental exposure limits to promote the safer agriculture use of this product, avoiding impacts to living organisms.

Slow delivery of biocide from nanostructured, microscaled, particles reduces its phytoxicity: A model investigation.

Nano-engineered delivery systems have emerged as possible solutions for more efficient pest management in agriculture. Likewise for nanostructured drug delivery systems (DDS) in medicine, the use of biocide delivery systems (BDS) brought concerns on their toxicology on non-targeted organisms. Plants, for instance, are the foundation of the ecosystem, acting as primary actor in the food chain and is associated with the whole biodiversity, being strictly related to human health. This is a very important consideration to fully understand the benefits of using delivery systems for crop protection and production. Herein, a biocide delivery system was prepared by loading nanostructured, microscaled, biogenic silica particles with thymol, a known phytotoxicant. The resulting system contains 120 mg of thymol per gram of silica and displays slow release features. The Allium cepa bioassay was chosen to demonstrate how the toxicity and cellular damages induced by thymol can be significantly reduced through a slow, controlled, release strategy. The lower mobility of the reference particles associated with slow-delivery features reduced the toxicity and cellular damages caused by thymol in the plant genetic model.

Allium cepa test in environmental monitoring: a review on its application.

Higher plants are recognized as excellent genetic models to detect environmental mutagens and are frequently used in monitoring studies. Among the plant species, Alium cepa has been used to evaluate DNA damages, such as chromosome aberrations and disturbances in the mitotic cycle. Employing the A. cepa as a test system to detect mutagens dates back to the 40s. It has been used to this day to assess a great number of chemical agents, which contributes to its increasing application in environmental monitoring. The A. cepa is characterized as a low cost test. It is easily handled and has advantages over other short-term tests that require previous preparations of tested samples, as well as the addition of exogenous metabolic system. Higher plants, even showing low concentrations of oxidase enzymes and a limitation in the substrate specification in relation to other organism groups, present consistent results that may serve as a warning to other biological systems, since the target is DNA, common to all organisms. The A. cepa test also enables the evaluation of different endpoints. Among the endpoints, chromosome aberrations have been the most used one to detect genotoxicity along the years. The mitotic index and some nuclear abnormalities are used to evaluate citotoxicity and analyze micronucleus to verify mutagenicity of different chemicals. Moreover, the A. cepa test system provides important information to evaluate action mechanisms of an agent about its effects on the genetic material (clastogenic and/or aneugenic effects). In the face of all the advantages that the A. cepa test system offers, it has been widely used to assess the impacts caused by xenobiotics, characterizing an important tool for environmental monitoring studies, where satisfactory results have been reported.

Action mechanisms of petroleum hydrocarbons present in waters impacted by an oil spill on the genetic material of Allium cepa root cells.

Chromosomal aberration (CA) assays have been widely used, not only to assess the genotoxic effects of chemical agents, but also to evaluate their action mechanisms on the genetic material of exposed organisms. This is of particular interest, since such analyses provide a better knowledge related to the action of these agents on DNA. Among test organisms, Allium cepa is an outstanding species due to its sensitivity and suitable chromosomal features, which are essential for studies on chromosomal damage or disturbances in cell cycle. The goal of the present study was to analyze the action mechanisms of chemical agents present in petroleum polluted waters. Therefore, CA assay was carried out in A. cepa meristematic cells exposed to the Guaecá river waters, located in the city of São Sebastião, SP, Brazil, which had its waters impacted by an oil pipeline leak. Analyses of the aberration types showed clastogenic and aneugenic effects for the roots exposed to the polluted waters from Guaecá river, besides the induction of cell death. Probably all the observed effects were induced by the petroleum hydrocarbons derived from the oil leakage.

Chromosome aberration and micronucleus frequencies in Allium cepa cells exposed to petroleum polluted water--a case study.

In the present study, we applied Chromosome Aberration (CA) and Micronucleus (MN) tests to Allium cepa root cells, in order to evaluate the water quality of Guaecá river. This river, located in the city of São Sebastião, SP, Brazil, had been affected by an oil pipeline leak. Chemical analyses of Total Petroleum Hydrocarbons (TPHs) and Polycyclic Aromatic Hydrocarbons (PAHs) were also carried out in water samples, collected in July 2005 (dry season) and February 2006 (rainy season) in 4 different river sites. The largest CA and MN incidence in the meristematic cells of A. cepa was observed after exposure to water sample collected during the dry season, at the spring of the river, where the oil leak has arisen. The F(1) cells from roots exposed to such sample (non-merismatic region) were also analyzed for the incidence of MN, showing a larger frequency of irregularities, indicating a possible development of CA into MN. Lastly, our study reveals a direct correlation between water chemical analyses (contamination by TPHs and PAHs) and both genotoxic and mutagenic effects observed in exposed A. cepa cells.