[M-ZZ51] 環境汚染・環境毒性と生物

[MZZ51-12] Assessing the Net Benefits of Organic Farming interventions in Ecosystem Preservation against Emerging Pesticides

*COLLINS NIMAKO¹、Anri HIRAI¹、Takahiro ICHISE¹、Shouta MM NAKAYAMA^1,2、Mayumi Ishizuka¹、Yoshinori IKENAKA^1,3,4,5 (1.Laboratory of Toxicology, Department of Environmental Veterinary Sciences, Faculty of Veterinary Medicine, Hokkaido University, Hokkaido, Japan、2.Biomedical Sciences Department, School of Veterinary Medicine, The University of Zambia、3.Water Research Group, Unit for Environmental Sciences and Management, North-West University, Potchefstroom, South Africa、4.One Health Research Center, Hokkaido University, Hokkaido, Japan、5.Translational Research Unit, Veterinary Teaching Hospital, Faculty of Veterinary Medicine, Hokkaido University, Hokkaido, Japan)

キーワード：Pesticides, Neonicotinoids, Ecosystem, Organic Farming, Detection frequency, Metabolite

Pesticides are widely used in many sectors of life to safeguard global food security for the increasing human populations. Although pesticides offer numerous benefits to society, uncontrolled applications of pesticides may visit several devastating effects on ecosystem diversity. Lately, many concerns have been raised about the high global application rates of emerging pesticides such as Neonicotinoids (NNIs). This class of pesticides has been widely tagged as a potential threat to the ecosystem diversity due to their ubiquitous occurrence in the environment. Upon release into the environment, NNIs may undergo various metabolic transformations; and the resulting metabolites in-tandem with remnant residues of their parent compounds may percolate into various ecosystem compartments, thereby posing risks to aquatic, terrestrial, or avian species. Globally, organic farming practices have been tipped as potential countermeasures for ecosystem preservation against emerging pesticides, including NNIs. However, little is known if current organic interventional measures adopted in Japan are able to mitigate NNI exposures in the ecosystem or otherwise. Hence the current study sought to (1) assess the residual levels of NNIs in organic and conventional green tea leaves produced in Japan (hereafter known as food contamination studies) and, (ii) validate the efficacies of organic dietary interventions in ameliorating NNIs exposures and their potential toxicological effects in human populations (hereafter, known as exposure surveillance). Regarding the food contamination studies, a total of 103 tea leaves (thus, 42 organic and 61 conventional) were sampled from grocery stores in Japan. Concentrations of NNIs in the tea leaves were quantified using LC-MS/MS, and the data was used to estimate maximum daily intakes of NNIs within the Japanese population. Eight NNI compounds were detected in both organic and conventional tea leaves. Detection frequencies (%Dfs) of NNIs in the tea samples (n=103) were found in the decreasing order; thiacloprid (84.47%) > dinotefuran (74.76%) > imidacloprid (69.90%) ≈ clothianidin (69.90%) > dm-acetamiprid (63.11%) > thiamethoxam (58.25%) > acetamiprid (4.85%) > nitenpyram (1.94%). About 94.20% of the tea leaves contained two or more NNI compounds simultaneously. The %Dfs of NNIs were relatively lower in organic tea leaves compared to the conventional tea leaves. Various percentile concentrations of NNIs were far lower in organic tea leaves compared to conventional tea leaves. The maximum daily intakes of NNIs through consumption of tea were also lower for organic tea leaves compared to the conventional tea samples. In the case of the human exposure surveillance, a total of 103 Japanese volunteers were recruited and fed strictly with either organic diets for 5 or 30 days or with conventional diets. Then the exposure rates of eight NNI compounds were determined in the population. Subsequently, the residual levels of NNIs were determined in organic and conventional green tea leaves produced in Japan. After analysis, eight NNIs were detected in the target population; but the detection rates were far lower in the organic diet consumers compared to conventional diet consumers. The organic dietary intervention drastically reduced the cumulative levels and the daily intake rates of the target pesticides within the studied population. Seven NNI compounds and one NNI metabolite were detected in Japanese tea leaves cultivated by strict organic farming methods. However, the detection rates of pesticides were relatively lower in organic tea leaves than conventional tea leaves. Moreover, the daily exposure rates of pesticides through green tea consumption were far lower for organic tea leaves than conventional tea leaves. Findings from the current study ultimately show that the adoption of organic farming interventions may offer optimum ameliorative outcomes on pesticide exposure rates within the ecosystem.