Genotoxic potential generated by biomass burning in the Brazilian Legal Amazon by Tradescantia micronucleus bioassay: a toxicity assessment study.

BACKGROUND: The Brazilian Amazon has suffered impacts from non-sustainable economic development, especially owing to the expansion of agricultural commodities into forest areas. The Tangará da Serra region, located in the southern of the Legal Amazon, is characterized by non-mechanized sugar cane production. In addition, it lies on the dispersion path of the pollution plume generated by biomass burning. The aim of this study was to assess the genotoxic potential of the atmosphere in the Tangará da Serra region, using Tradescantia pallida as in situ bioindicator. METHODS: The study was conducted during the dry and rainy seasons, where the plants were exposed to two types of exposure, active and passive. RESULTS: The results showed that in all the sampling seasons, irrespective of exposure type, there was an increase in micronucleus frequency, compared to control and that it was statistically significant in the dry season. A strong and significant relationship was also observed between the increase in micronucleus incidence and the rise in fine particulate matter, and hospital morbidity from respiratory diseases in children. CONCLUSIONS: Based on the results, we demonstrated that pollutants generated by biomass burning in the Brazilian Amazon can induce genetic damage in test plants that was more prominent during dry season, and correlated with the level of particulates and elevated respiratory morbidity.

Buccal micronucleus cytome assay: Inter-laboratory scoring exercise and micronucleus and nuclear abnormalities frequencies in different populations from Brazil.

The Buccal Micronucleus Cytome Assay (BMCyt) has become an important biomonitoring tool for assessing cytogenetic damage in many studied populations. Each laboratory applies protocols that vary according to the method of collecting and preparing samples. Besides, Brazil is a country of great territorial extensions that received immigrants from various parts of the world with different genetic backgrounds. Therefore, the present study aimed to evaluate the inter-laboratory variation in scoring the same set of slides using the more comprehensive scoring criteria, to standardize the BMCyt protocol, to observe the basal alterations in populations of different Brazilian regions and to compare it with other places around the world. Our results showed that a valuable number of laboratories participated, ten laboratories from different regions of the country, for the validation of the BMCyt in human biomonitoring studies, resulting in the 804 healthy individuals. This was possible because we observed: a range of measures needs to be considered, such as the baseline frequency of DNA damage and cell death in non-exposed individuals; age when grouped showed an influence on DNA damage, although when evaluated by group we did not see an influence; association between smoking habit and all endpoints of the BMCyt (except karyolytic cells) was evident; the basal MN frequency, in the majority of groups, follows those around the world; and the BMCyt was confirmed as a good health status biomarker. We emphasize the need for constant discussions on the parameters of cell death due to greater difficulty among the analyzers.

Evaluation of the relationship of the molecular aggregation state of amphotericin B in medium to its genotoxic potential.

This work analyzes the genotoxicity potential, in the G2 phase of the cellular cycle, of an amphotericin B (AmB) commercially available form (Fungizone), and correlates it with the physicochemical properties of this product in aqueous media. The genotoxic studies were performed using peripheral blood lymphocytes from human donors. The chromosome aberrations and mitotic index were determined. Absorption spectra of Fungizone were obtained by dispersion of the stock solution in water for injection at various AmB concentrations, and using different cuvette path lengths for spectrophotometric determination. The absorption spectra of Fungizone in water are concentration dependent. High concentrations of Fungizone present a spectrum with an intense band at 340 nm, characteristic of AmB self-association. Conversely, at low concentrations, the spectra are similar to those obtained with AmB in methanol, with a positive band at 409 nm, assigned to AmB monomeric form. Similarly, the cytogenetic analysis shows an important decrease on the mitotic index, which is also concentration dependent when compared with control. Furthermore, the chromosome aberrations present a small, not statistically significant, increase only at the highest concentration. The results suggest that the Fungizone presents a cytotoxicity similar to membrane pore formation in mammalian cells that depends on the existence of self-associated AmB. In the presence of only monomeric forms, this phenomenon disappears. However, no genotoxicity was observed in this study.