Quantitative elucidation of the transfer of the neonicotinoid pesticide clothianidin to the breast milk in mice

• Published in: Toxicology letters Vol. 373; pp. 33 - 40
• Main Authors: Shoda, Asuka, Nishi, Misaki, Murata, Midori, Mantani, Youhei, Yokoyama, Toshifumi, Hirano, Tetsushi, Ikenaka, Yoshinori, Hoshi, Nobuhiko
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.01.2023
• Subjects: Breast milk; Clothianidin; Fetomaternal transfer; Maternal blood; Metabolites; Neonicotinoid; Maternal blood; Neonicotinoid; Fetomaternal transfer; Metabolites; Clothianidin; Breast milk
• ISSN: 0378-4274; 1879-3169
• DOI: 10.1016/j.toxlet.2022.10.006

Neonicotinoid pesticides (NNs) have been reported to have neurobehavioral effects on offspring after fetal and lactational exposure. In this study, clothianidin (CLO), an NN, was administered orally as a single dose (6.5 mg/kg: 1/10 of the no-observed-adverse-effect level in the current Pesticide Evaluation Report) to 10-day post-partum ICR mice, and CLO and its metabolites desmethyl-CLO (dm-CLO) were quantified using liquid chromatography-electrospray ionization/tandem mass spectrometry (LC-ESI/MS/MS) after collecting maternal breast milk and blood samples over time (1, 3, 6, 9, 12, and 24 h after administration). CLO and dm-CLO were detected in the breast milk at 1 h after the administration, and their concentrations were significantly higher than those in blood at all time points. The concentrations of CLO and dm-CLO in the breast milk were at their highest levels at 1 and 3 h, respectively, and then decreased over time to become almost undetectable at 24 h after the administration. These results show that CLO is metabolized in the mother’s body and is rapidly transferred to and concentrated in the breast milk. Since CLO concentrations in breast milk are higher than those in the blood, there is concern about the effects of CLO during lactation. •CLO is metabolized maternally in mice and rapidly transferred in breast milk.•CLO and metabolites are more highly concentrated in breast milk than maternal blood.•Most of CLO and its metabolites were eliminated from the mother's body within 24 h.•Infants are sensitive to chemicals, so adverse CLO effects in infants are a concern.