Neonicotinoid Occurrence and Its Potential Toxicity Level in Tropical Environmental Waters of Indonesia

Indonesia as a megadiverse country and the third largest rice producer in the world utilizes neonicotinoids, a group of systemic insecticides reported to have polluted environmental waters and reduced the abundance of aquatic invertebrates mostly in sub-tropical and temperate countries. To date, no study and regulation on neonicotinoid pollution have been established in Indonesian environmental waters which situates in tropical zone. This research investigated neonicotinoid pollution in seven types of environmental waters of Indramayu Regency (one of the largest rice-producing areas in Indonesia), and assessed the potential risk and toxicity level of detected neonicotinoids to the tropical aquatic environment. Data collections included water sampling and analysis using LC/MS/MS. Results showed that the detection frequency of neonicotinoids was 53% (in 17 out of 32 samples), with imidacloprid and thiamethoxam being the most common compounds detected. The highest total concentration (140.26 ng/L) and the highest concentrations of imidacloprid, thiamethoxam, thiacloprid, dinotefuran, and acetamiprid (48.98 ng/L, 65.14 ng/L, 16.66 ng/L, 23.12 ng/L, and 25.04 ng/L, respectively) were detected in estuaries and mangrove areas. No sample was found to have neonicotinoid concentration above the acute and chronic toxicities of several tropical aquatic organisms assessed. About 19% of the samples contained imidacloprid exceeding the chronic thresholds regulated by The Netherlands, while 6% were also above The United States' regulation, thus encouraging the establishment of necessary actions to prevent unwanted disturbance to the aquatic ecosystem. This study delivered the first report of the occurrence of seven neonicotinoid compounds in seven types of Indonesian environmental waters.