Abstract: Since 2008, Brazil has become one of the largest consumers of pesticides in the world. Many of these compounds have already been banned in several countries due to the negative effects they have on human health. Studies show that pesticides have a broad relationship with the increase in cases of diseases that mostly involve the nervous system and cancer. Soft Agar Colony Formation Assay is a test used to determine the carcinogenicity of a compound. It is based on the hypothesis that healthy cells cannot grow off a solid surface, but modified cells (malignant transformations) will have this ability and form colonies.

In order to study the cytotoxicity and carcinogenicity of PM2.5 collected in cities in the state of São Paulo (São Paulo, Piracicaba, and Capuava), human lung cells (BEAS-2B) were separately exposed for 7 days to both PM2.5 collected at these sites, and different pesticide patterns that were found in representative concentrations in the samples. For this, the violet crystal assay and Solft Agar were used.

The PM2.5 samples collected at all sampling sites with concentrations (C1 = 5 μg/m3 , C2 = 25 μg/m3 , and C3 = 50 μg/m3 ) showed cytotoxicity from 72h of exposure. Piracicaba was the site with the highest cytotoxicity, followed by Capuava and São Paulo. In the case of pesticides (C1=300 pg/m3 and C2=3000 pg/m3 ), during the first 4 days of exposure no significant differences were found between pesticides and control. From the 5th day on, different behaviors were observed, but further studies are needed to understand the cytotoxicity of these compounds. Based on the hypothesis that more carcinogenic compounds can form more colonies in the soft agar, the results show the tumorigenic effect of PM2.5 (C=5 μg/m3 ), with Piracicaba again being the site with the greatest effects. In the case of pesticides, only Atrazine (ATRA) and the substance containing a mixture of 25 pesticides (MIXG) showed tumorigenic effects for both concentrations, but this effect was smaller than that found for PM2.5. Statistically, there are no significant differences between the results for exposure to ATRA and MIXG. This indicates that the tumorigenic effect found in MIXG may be influenced by the presence of ATRA. To date, no references have been found to similar studies carried out on samples of particulate matter collected at sites in the state of São Paulo, nor on the pesticides of interest, thus having great relevance to the results found in this research.

Keywords: Particulate matter, Pesticide inhalation, Cytotoxicity, Carcinogenicity, Soft agar