Abstract: Since 2008, Brazil has become the largest consumer of pesticides worldwide. This development follows four decades of governmental investments aimed at modernizing Brazilian agriculture. An unintended consequence of pesticide consumption has been the steady growth of human health problems and environmental contamination. This paper provides an in-depth analysis of how pesticides are routinely handled by smallholders in a tropical region of the Rio de Janeiro state and the potential environmental post-application fate based on chemical product characteristics. While our results do not confirm that the farmers’ apparent careless handling of pesticides is linked to an intentional disregard for intoxication risk, they do point to a more complex set of explanatory variables that include: labor scarcity, inadequacy of protective gear, mixing practices, and limited educational effectiveness of labeling standards. Mixing practices may be increasing the risk to human health and to the environment, especially given the toxicity levels of the fifteen active ingredients identified in this study. For ten of the commercially used pesticides identified we suggest further study. These chemicals can potentially contaminate groundwater through leaching and run-off due to their physicochemical characteristics which facilitate their mobility in the soil layers. Given the large consumption of pesticides in Brazil and the risks listed herein, we find urgent to address legislation, labeling, training and other measures that would provide incentives to reduce intoxication risks to both Brazilian farmers and the environment. [Marcos Antonio Pedlowski, Maria Cristina Canela, Maria Alice da Costa Terra & Rogéria Maria Ramos de Faria (2012). Modes of pesticides utilization by Brazilian smallholders and their implications for human health and the environment. Crop Protection, 31(1), 113-118, dx.