Within-individual and interlaboratory variability analyses of urinary metabolites measurements of organophosphorus insecticides

Yuki Ito, Jun Ueyama, Shoji F. Nakayama, Tomohiko Isobe, Naoko Oya, Hirotaka Sato, Takeshi Ebara, Kouichi Yoshimasu, Kanami Tsuno, Nozomi Tatsuta, Kunihiko Nakai, Michihiro Kamijima

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


Single-spot urine is often used to estimate organophosphorus insecticide (OP) exposure. However, variations of urinary metabolite concentrations during the day are considerable as OP half-lives are short and as diet is their main exposure source. In addition, quality control is indispensable for institutions that analyze these metabolites. This study aimed to clarify (1) adequate frequencies of urine collection for estimating OP exposure and (2) interlaboratory variation in measured concentrations of OP metabolites, dialkylphosphates (DAPs). To quantify intra-individual variations, urine was collected eight times during a period that spanned 5 consecutive days from nine children aged 5–6 years. For interlaboratory variations, 41 spot samples from 14 pregnant women and 13 three-year-old children were used. Intraclass correlation coefficients for the DAPs were moderate but misclassification occurred in > 50% of the surrogate category analyses using single measurements. The misclassification frequency decreased to satisfactory levels when three temporal measurements were conducted. Values of four DAPs measured in the two laboratories correlated well except in the cases of urine samples obtained from two pregnant women. In conclusion, urinary DAPs should be measured from spot urine samples obtained during 3 different days. Sharing matrix-contained standards and quality control samples should minimize interlaboratory variations.

Original languageEnglish
Pages (from-to)721-729
Number of pages9
JournalJournal of Exposure Science and Environmental Epidemiology
Issue number4
Publication statusPublished - 2020 Jul 1


  • Biomonitoring
  • Interlaboratory variability
  • Organophosphorus insecticides
  • Urine
  • Within-individual variability

ASJC Scopus subject areas

  • Epidemiology
  • Toxicology
  • Pollution
  • Public Health, Environmental and Occupational Health


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