title: Quantitative analysis of organophosphate insecticide metabolites in urine extracted from disposable diapers of toddlers in Japan.
abstract: Epidemiological studies linking insecticide exposure to childhood neurodevelopment have been gaining global attention. Despite the rapid development of the central nervous system in early childhood, studies regarding the biological monitoring of insecticide exposure in diapered children are limited. In this study, we aimed to clarify the concentrations of organophosphate (OP) insecticide metabolites in toddler urine extracted from disposable diapers in Japan.
  
  
  
  We recruited diapered children from the Aichi regional subcohort participants of the Japan Environment and Children's Study (JECS) at the time of their 18-month checkup. A total of 116 children wore designated disposable diapers overnight, which were then sent as refrigerated cargo. The urine was extracted from the diapers using acetone and analyzed by ultra-performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS) to determine the concentrations of six dialkyl phosphates (DAPs) (i.e., dimethyl phosphate [DMP], dimethyl thiophosphate [DMTP], dimethyl dithiophosphate [DMDTP], diethyl phosphate [DEP], diethyl thiophosphate [DETP], and diethyl dithiophosphate [DEDTP]). DAP absorption into the diapers was quantified to calculate the urinary DAP concentrations.
  
  
  
  The DAP recovery using the developed method yielded between 54.2% (DEDTP) and 101.4% (DEP). Within-run precision expressed as the relative standard deviation was between 2.4% and 14.7%, and the between-run precision was between 3.1% and 8.5%. A Bland-Altman analysis confirmed the agreement between the results obtained by the developed method and by the measurements for the corresponding urine without diaper absorption. The geometric means (GM) of urinary DMP, DMTP, DMDTP, DEP, DETP, and total DAPs (ΣDAP) were 3.6, 3.9, 0.9, 6.0, 0.6μg/L, and 137.6 nmol/L, respectively. The GM of DEDTP was not calculated due to its low detection rate.
  
  
  
  We successfully established a method to measure the DAP concentrations in urine extracted from diapers and this is the first report of these pesticide concentrations in diapered children in Japan.
authors: Department of Occupational and Environmental Health, Nagoya City University Graduate School of Medical Sciences, Japan.
authors: Naoko
authors: N
authors: Oya
authors: Department of Occupational and Environmental Health, Nagoya City University Graduate School of Medical Sciences, Japan. Electronic address: yukey@med.nagoya-cu.ac.jp.
authors: Yuki
authors: Y
authors: Ito
authors: Department of Occupational and Environmental Health, Nagoya City University Graduate School of Medical Sciences, Japan.
authors: Keisuke
authors: K
authors: Hioki
authors: Department of Occupational and Environmental Health, Nagoya City University Graduate School of Medical Sciences, Japan.
authors: Yuya
authors: Y
authors: Asai
authors: Department of Pathophysiological Laboratory Sciences, Field of Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, Japan.
authors: Arisa
authors: A
authors: Aoi
authors: Department of Pathophysiological Laboratory Sciences, Field of Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, Japan.
authors: Yuka
authors: Y
authors: Sugiura
authors: Department of Pathophysiological Laboratory Sciences, Field of Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, Japan.
authors: Jun
authors: J
authors: Ueyama
authors: Department of Occupational and Environmental Health, Nagoya City University Graduate School of Medical Sciences, Japan.
authors: Tomoko
authors: T
authors: Oguri
authors: Department of Occupational and Environmental Health, Nagoya City University Graduate School of Medical Sciences, Japan.
authors: Sayaka
authors: S
authors: Kato
authors: Department of Occupational and Environmental Health, Nagoya City University Graduate School of Medical Sciences, Japan.
authors: Takeshi
authors: T
authors: Ebara
authors: Department of Occupational and Environmental Health, Nagoya City University Graduate School of Medical Sciences, Japan. Electronic address: kamijima@med.nagoya-cu.ac.jp.
authors: Michihiro
authors: M
authors: Kamijima
mesh_terms: D041381:Diapers, Infant; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000652:urine*; D005260:Female; D006801:Humans; D007223:Infant; D007306:Insecticides / Q000652:urine*; D007564:Japan; D008297:Male; D010755:Organophosphates / Q000652:urine*
chemical_list: D004785:Environmental Pollutants; D007306:Insecticides; D010755:Organophosphates
keywords: Child; Dialkyl phosphates; Disposable diaper; Liquid chromatography-tandem mass spectrometry; Organophosphate insecticide; Urine