Survey on Dioxin Contamination in Chinese-Produced Pesticides and Evaluation of Dioxin Emissions During their Application
摘要
An investigation into dioxin contamination in Chinese pesticides was conducted using an improved detection method, analyzing 390 batches of Chinese-produced 2,4-D and its derivative active ingredients, along with 32 commonly used pesticide formulations. Dioxin concentrations of the raw active ingredients ranged from 0.00721 to 98.9 pg TEQ·g-1, all below the strictest current regulatory limit set by the United States (100 pg TEQ·g-1). Nevertheless, only 1.03% of the samples met the advanced process level specified in the UNEP 2013 Toolkit (0.1 pg TEQ·g-1). As the world's largest exporter of 2,4-D and its derivative active ingredients, China has considerable room for improvement in its production standards. Fingerprint characteristic analysis identified chlorophenols as the primary source of dioxin contamination. Notably, the dioxin content in three formulations—butachlor, atrazine, and imidacloprid—was significantly higher than that in known high-risk pesticide formulations. Analysis of raw materials and production processes indicated a high likelihood of contamination introduced by auxiliary materials. Currently, the emission factors specified by the UNEP cover only a few recognized high-risk categories, all based on active ingredients, which may lead to an underestimation of overall emissions. Based on the detection results for formulations and national pesticide production data, annual dioxin emissions—expressed as toxic equivalent (TEQ)—from herbicides, insecticides, and fungicides ranged from 0.0302 to 5.55 g TEQ, with a median of 0.861 g TEQ per year. These three pesticide categories account for 94.6% of total pesticide use in China, thereby effectively reflecting the overall emission profile associated with pesticide application.