In Brazil, genetically modified (GM) crops were initially introduced illegally at the end of the 1990s and officially authorized in 2003. Six types of GM crops are authorized, but only three are effectively in use, namely, soybean, corn and cotton that are herbicide-resistant, insect-resistant or both.

A new study has identified and characterized changes in the patterns of use of pesticides and herbicides in Brazil from 2000 to 2012. The emphasis was on soybeans, the main commodity produced in the country, of which 90% of the crops are GM. In 2014, when pesticide sales in Brazil were the highest at US$12.2 billion, the cultivated area of GM crops reached 42.2 million hectares, which represented an increase of 1306.67% over the 3 million hectares registered in 2003.

The study found that contrary to the initial expectations of decreasing pesticide use following the adoption of GM crops, overall pesticide use in Brazil increased 1.6-fold between the years 2000 and 2012. During the same period, pesticide use for soybean increased 3-fold. However, this increase did not result in an increase in average productivity. The results obtained in this study agree with similar studies in the US, Argentina, and other parts of the world which strongly suggest that the adoption of GM crops increases pesticide use, specifically herbicides sprayed on soybean, with possible increases in environmental and human exposure and associated negative impacts.