Among the few studies assessing genetic damage in schoolchildren exposed to air pollution, none has assessed damage generated by exposure to pollutants released through biomass burning in the Amazon region.
A study conducted by Sisenando et al. [6
] in the same region of the Legal Amazon showed a delimitation of two well-defined climatic periods (dry and rainy). This fact influences concentration and dispersion of pollutants, given that pollution generated by biomass burning in the Amazon reaches its peak during the dry season (May-October). Results of PM2.5
modeled in the study region show that TS and PV areas presented much higher particulate matter values than the control area, this validating the choice of CH as a control in this study and corroborates with the toxicity evaluation study of Sisenando et al. [6
] who also chose this same area as a control. With respect to meteorological variables, results presented show no significant difference between mean temperatures modeled among the areas. Higher humidity in Porto Velho in comparison to other points is justified by the fact that the area is part of the Amazon biome and consequently suffers greater influence from humidity emanating from the Amazon rainforest [39
Baseline MN frequency obtained in CH (control area) is in agreement with values observed by Holland et al. [17
] in the review article of the Human Micronucleus Project on Exfoliated Buccal Cells (HUMNXL
) regarding the baseline observed in articles that evaluated environmental pollutants. Comparison between areas exposed and not exposed to pollution showed that children exposed to pollution have a higher frequency of micronuclei. These results corroborate studies by Maimulov et al. [28
] in Russia, Lahiri et al. [30
] India, Huen et al. [24
] and Chen et al. [41
] in the United States that evaluated the influence of air pollution in formation of micronuclei in children. The highest MN‰ observed in TS in relation to PV although not significant confirms the results of modeled particulate material on that TS was the area most exposed in both periods analyzed. This difference in particulate matter concentration observed in TS may be associated with burning of sugar cane in the area. Sisenando et al. [6
] and Alves et al. [9
] showed the genotoxic ability of pollutants generated by burning sugar cane in the TS region using the bioindicator Tradescantia pallida in situ
and ex situ
experiments. Alves et al. [9
] also detected the presence of PAHs with high mutagenic potential (e.g.: benzo[e]pyrene) and n-alkanes in the sampled through Teflon filters in the troposphere of Tangará da Serra during the dry season.
In Brazil, consumption of vegetables, fruit and animal protein is associated with cultural values, and consumption of vitamin supplementation is expensive and restricted to individuals with greater buying power. Bonassi et al. [42
] in a review article of the HUMNXL
project shows that factors related to lifestyle and diet may influence frequency of micronuclei. In this study, the factor of alcohol and tobacco consumption was minimized at time of collection and the cultural factor was minimized by choosing areas (test and control) with similar cultural values. Although in the study region there is a clear economic difference between users of public and private schools, this fact did not provide significant differences between the two groups.
More recent publication HUMNXL
project showed that people who eat fish regularly have a lower baseline MN frequency compared to non-consumers of fish [42
When comparing household per capita consumption of fish between the two test areas, we found that fish consumption in PV was 2.31 times higher than in TS [43
]. This may help to explain the low frequency of micronuclei observed in PV. Regarding gender, the results no showed significant difference between males and females. This result corroborates the review articles of Neri et al. [16
] and Bonassi et al. [42
] and did not corroborate the study of Maimulov et al. [28
] which showed that female children were more sensitive to environmental pollution in St. Petersburg. In relation to age, the results showed a slight yet not significant increase in MN frequency in all areas. This observation is in accordance with Bonassi et al. [42
] which showed that frequency of micronuclei constantly increases with age. In general, significant differences were observed when comparing data obtained in sites TS and PV with those from CH in all parameters, except between MN‰ in children under 07 years old from PV that was not significant in comparison to the control (p > 0.05
). This fact can be explained by the small sample size in this age group.
A fact that could be considered a limitation of this study was the small number of children who participate in the study in the public school of Chapada dos Guimarães and the inability to conduct the study in the private school of Porto Velho. However, this study is marked by the pioneering character in the assessment of genotoxicity in an area of difficult access and with few environmental monitoring stations.