The current study sought to assess the residual levels of neonicotinoid insecticides (NEO) in organic and conventional green tea leaves produced in Japan. A total of 103 tea leaves (thus, 42 organic and 61 conventional), were sampled from grocery stores in Japan. Concentrations of NEOs in the tea leaves were quantified using LC–MS/MS; and the data was used to estimate maximum daily intakes of NEOs within the Japanese population. Seven native NEO compounds and one NEO metabolite were detected in both organic and conventional tea leaves. Detection frequencies (%Dfs) of NEOs 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 NEO compounds simultaneously. The %Dfs of NEOs were relatively lower in organic tea leaves, compared to the conventional tea leaves. Various percentile concentrations of NEOs were far lower in organic tea leaves, compared to the conventional tea leaves. The maximum daily intakes of NEOs through consumption of tea (MDIgt) were also lower for organic tea leaves, compared to the conventional tea samples.

Toxicological effects of neonicotinoid insecticides (NNIs) have been reported for mammals, such as humans, rats, and mice. However, there are limited reports on their toxic effects on wild mammals. To predict NNI-induced toxic effects on wild mammals, it is necessary to determine the exposure levels and metabolic ability of these species. We considered that raccoons could be an animal model for evaluating NNI-induced toxicities on wildlife because they live near agricultural fields and eat crops treated with NNIs. The objective of the present study was to estimate the effects of NNI exposure on wild raccoons. Urinary concentrations of NNI compounds (n = 59) and cytochrome P450-dependent metabolism of NNIs (n = 3) were evaluated in wild raccoons captured in Hokkaido, Japan, in 2020. We detected either one of the six NNIs or one metabolite, including acetamiprid, imidacloprid, clothianidin, dinotefuran, thiacloprid, thiamethoxam, and desmethyl-acetamiprid in 90% of raccoons (53/59); the average cumulative concentration of the seven NNI compounds was 3.1 ng/ml. The urinary concentrations were not much different from those reported previously for humans. Furthermore, we performed an in vitro assessment of the ability of raccoons to metabolize NNIs using hepatic microsomes. The amounts of NNI metabolites were measured using liquid chromatography–electrospray ionization–tandem mass spectrometry and compared with those in rats. Raccoons showed much lower metabolic ability; the maximum velocity/Michaelis–Menten constant (Vmax/Km) values for raccoons were one-tenth to one-third of those for rats. For the first time, we show that wild raccoons could be frequently exposed to NNIs in the environment, and that the cytochrome P450-dependent metabolism of NNIs in the livers of raccoons might be low. Our results contribute to a better understanding of the effects of NNIs on raccoons, leading to better conservation efforts for wild mammals. Environ Toxicol Chem 2022;41:1865–1874. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Neonicotinoids, a neuro-effective class of insecticides, are heavily applied in agricultural activities worldwide. Poultry can be exposed to neonicotinoids by several routes, but the knowledge of neonicotinoid’s metabolism in poultry and its associated interspecies differences is highly limited. Hence, this study aims to investigate the species differences in metabolite formations, as well as cytochrome P450 (CYP)-dependent metabolism of four major neonicotinoid compounds, acetamiprid, imidacloprid, clothianidin, and thiamethoxam, in poultry. In vitro biotransformation assays using hepatic microsomes of chicken, ducks, geese, quails, and rats were conducted. Metabolites of neonicotinoids were then screened by LC/Q-TOF and quantified by LC/MS/MS. The results revealed an existence of interspecies differences in the formations of N-[(6-chloro-3-pyridyl) methyl] -N-methyl acetamidine (IM-1-5) of acetamiprid and dm-clothianidin of clothianidin between chicken and other species. In addition, the greatest CYP activities in the metabolism of most neonicotinoid substrates, such as acetamiprid to dm-acetamiprid, imidacloprid to hydroxylated-imidacloprid and imidacloprid-olefin, clothianidin to dm-clothianidin, and thiamethoxam to clothianidin, were found in chicken. These results suggested that the CYPs in chicken may have a greater capacity for metabolism of neonicotinoids compared to other poultry. This study further revealed that the maximum intrinsic clearance of dn-imidacloprid and dn-clothianidin in ducks may be superintended by CYP-mediated nitro-reductions of imidacloprid and clothianidin. Further studies employing CYP recombinant enzymes may be required to elucidate the specific CYP isoforms that may be involved in neonicotinoid metabolism in avian species.

Pesticides are widely used to meet the food demands of a growing population, with various types used to control pests depending on the crops grown. Rainfall, overspray, and runoff from agricultural fields can wash these insecticides into water bodies, posing documented environmental risks. Imidacloprid is commonly used in Afrotropical regions such as South Africa, yet limited information is available on its toxicity to aquatic ecosystems within this climate region. To address this, a 16-week outdoor microcosm study was conducted, exposing aquatic communities to 0.1, 10, and 250 µg/L of imidacloprid under natural conditions. Physicochemical parameters, such as pH, dissolved oxygen, temperature, and various others, were monitored regularly. The microbial community, organic decomposition, and zooplankton were largely unaffected by the exposure to imidacloprid. In contrast, 10 and 250 µg/L of imidacloprid led to long-term effects on the macroinvertebrate community, while short-term effects were found in the 0.1-µg/L treatment. Families such as Coenagrionidae were affected across all treatments, while Caenidae and Notonectidae were affected in only the highest treatment. Changes in the community structure resulted in reduced predator abundance (e.g., Coenagrionidae, Libellulidae, and Notonectidae) and increased filter feeders (Culicidae). High temperatures likely increased the toxicity to arthropods when compared with similar studies with lower light intensities and temperatures. Recovery was limited during the postexposure period, with some families (Baetidae) rebounding quickly, while others (Caenidae and Coenagrionidae) showed delayed recovery. Full recovery of the macroinvertebrate community systems did not occur during the eight-week recovery period, highlighting the importance of unexposed refuges for recolonization. This study provides important field-realistic evidence of the ecological risks associated with imidacloprid use in Southern African freshwater systems.

The rapid population growth across Africa has increased the demand for food production, resulting in increased pesticide use. South Africa is among the top four pesticide importers in Sub-Saharan Africa, raising significant concerns regarding the contamination of freshwater ecosystems. Organochlorine pesticides (OCPs), historically used for agriculture and vector control, persist in the environment due to their high lipophilicity and long half-lives. Despite bans on many OCPs, residues remain in aquatic systems, potentially affecting non-target organisms such as fish. Similarly, neonicotinoids, introduced as safer alternatives, are now linked to adverse effects on aquatic biota, yet little is known about their bioaccumulation in wild fish species in southern Africa. This study investigated 13 neonicotinoids and 19 OCPs in fish muscle tissue from the Inkomati and Letaba catchments. Only two OCPs, p,p’ -DDE and p,p’ -DDD, were detected, likely due to ongoing DDT use in malaria control. Concentrations were generally low and varied between sites, with higher values found in the Letaba catchment. Neonicotinoids were detected at low concentrations, with acetamiprid and imidacloprid being the most prevalent, although the concentrations were lower than those reported globally. Muscle tissue, representing long-term exposure, may underestimate total pesticide burdens due to lower lipid content than other tissue types. Findings suggest that the detected residues reflect the persistent legacy of historical DDT use, potential ongoing localised DDT use for malaria vector control, as well as ongoing neonicotinoid use in agricultural systems. Although concentrations were below levels of concern for vertebrates, this study highlights the need for continued monitoring and expanded tissue analysis to better understand bioaccumulation and ecological risks in southern African freshwater systems.