Pesticide-loss Simulation and Health Risk Assessment during the Flood Season in Watershed Systems

There have been growing concerns over the negative effects of pesticide usage on human health and environmental sustainability. Pesticide residues, if they enter water bodies, will impair water quality and pose risks to human health. During flood season, floodwater could wash off large amount of pesticide residues to rivers and lakes. A pesticide-loss simulation and health-risk assessment (PSHA) system was developed to predict pesticide losses and evaluate associated health risks during flood season. A case study was conducted in the Auglaize-Blanchard Watershed in Ohio to calibrate and verify the proposed system. The results showed a reasonable prediction accuracy and model performance. The PSHA system was then applied to estimate pesticide losses and assess health risks during May 1997 to April 1998, especially during the flood season from May to August. The results show that water discharge during the flood season contributed 90 percent of the total pesticide losses. The chronic and acute health risks were then quantified and the results showed that the health risks caused by atrazine losses were markedly high during flood season. Therefore, pesticides applied during flood season would cause more serious pollution problems and higher health risks than that in other times. Flood season was shown to be a critical period for not only controlling flooding hazards but also mitigating pesticide pollution.