Pesticide Contamination and Environmental Health Risk Assessment in Typical Rice Growing Areas of China

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Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Medicine & Dentistry
Griffith Health
Pymetrozine has replaced the toxic organophosphate pesticides that were previously used for rice crops in China. Owing to its recent introduction, there are limited studies on the residuals and dynamics of Pymetrozine in the environment. The existing data usually pertain to application studies on artificially constructed plots. Such studies do not adequately address the behaviour of natural dynamics and residuals of Pymetrozine in actual field conditions. Therefore, it is necessary to carry out studies under field conditions to investigate the natural dynamics and residuals of Pymetrozine in typical rice-growing areas in China. In addition, residents living close to agricultural lands might be exposed to pesticides through environmental pathways including spray drift and volatilisation of pesticides beyond the treated area. Most studies about the metabolism, environmental distribution, fate and exposure of Pymetrozine have been carried out in laboratory conditions. However, these experiments cannot represent the natural dynamics and residuals and its exposure and human health risk in the field situation. Therefore, it is necessary to systematically assess Pymetrozine exposures and potential health risks through the environmental routes for residents living close to agricultural lands in field situations. This study was carried out in two rice growing areas in China: Guangxi Province and Hunan Province. Surface soil and paddy water samples were collected in each area on the day prior to spraying and up to the 28th day after pesticide application in June 2019. A modified Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) method was used to extract the target analyte. Parameters including linearity, linear range, LOQs, accuracy, precision and stability were considered to evaluate the method validation. Calibration curve analysis and kinetic evaluation methods were used to discuss the dynamics and residual levels of Pymetrozine. In addition, data on the registrat