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Pollutant Emitted by Forest Fire Causes DNA Damage and Lung Cell Death

Publicado em 25 outubro 2017

The main culprit appears to be retene, a chemical compound that belongs to the class of polycyclic aromatic hydrocarbons (PAHs).

These are some of the main findings of a study published by a group of Brazilian researchers on September 7, 2017, in the journal Scientific Reports.

“We found no information on the toxicity of retene in the scientific literature. I hope our findings serve as an incentive for the compound to be better studied and for its environmental concentrations to be regulated by health organizations,” said Nilmara de Oliveira Alves Brito, first author of the article and awardee of a postdoctoral scholarship from FAPESP.

The study was conducted under the supervision of Carlos Menck, a professor at the University of São Paulo’s Biomedical Science Institute (ICB-USP), and Silvia Regina Batistuzzo, a professor at the Federal University of Rio Grande do Norte (UFRN). The research group also included Paulo Saldiva , a professor at the University of São Paulo’s Medical School (FM-USP), and Paulo Artaxo, a professor at the same university’s Physics Institute (IF-USP), as well as scientists at the Federal University of Rio de Janeiro (UFRJ), Oswaldo Cruz Foundation (FIOCRUZ), and Washington University in Saint Louis in the United States.

“When I was doing my master’s research at UFRN, I noticed that exposure of lung cells to this particulate matter emitted by biomass burning led to mutations in lung cell DNA,” Alves Brito said. “This more recent study set out to investigate the mechanisms by which this happens.”


The first step, she explained, consisted of determining the concentration of pollutants to be used in the lab experiments designed to mimic the exposure suffered by people who live in the area of intensely changing land use and plant cover known as the “deforestation arc” — 500,000 square kilometers extending westward from eastern and southern Pará into Mato Grosso, Rondônia and Acre.

Using mathematical models, the researchers calculated the human lung’s capacity to inhale particulate matter at the height of the burning season and the percentage of pollutants that is deposited in lung cells. “Based on this theoretical mass, we determined the concentration levels to be tested using cultured cells,” Alves Brito said.

The pollutants used in vitro were collected in a natural area near Porto Velho, Rondônia, during the burning season, which peaks in September and October.

“The samples were collected using a device that draws in air and deposits fine particles with a diameter of less than 10 micrometers in a filter. We were interested in studying these very fine particles because they’re small enough to penetrate the alveoli in the lungs,” Alves Brito said.

According to Artaxo, the filters were frozen shortly after the particulate matter was collected because the organic compounds found in the pollution plume are highly volatile.

“This material was shipped to São Paulo and diluted in a nutritive solution, which was then applied to the cell cultures,” he said. “The proportion of pollutants used was the same as that found in the air inhaled by the inhabitants of Porto Velho.”

The cultured cells treated with the solution were compared with a group of control cells, which received only the solvent used to extract pollutants from the filters. The aim was to confirm that any adverse effects observed were caused by the particulate matter and not by the solvent.

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