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

Abstract

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.

Figure 1

Spatial distribution of the study site, delimiting the southern region of the Legal Amazon and the cities studied. Georeferencing of sampling stations for the Tradescantia-micronucleus (Trad-MCN) assay.

Figure 2

Active exposure, micronuclei frequency in T. pallida at the study sites. ^#p < 0.05 and ^##p < 0.01 by Kruskal-Wallis. *p < 0.05 and **p < 0.01 by Mann-Whitney.

Figure 3

Passive exposure, micronuclei frequency in T. pallida at the study sites. ^#p < 0.05 and ^##p < 0.01 by Kruskal-Wallis. *p < 0.05 and **p < 0.01 by Mann-Whitney.

Figure 4

Micronucleus frequencies in T. pallida in active and passive monitoring. D = dry season. R = rainy season. Spearman's correlation coefficient (r and p) for the two types of exposure.