TY - JOUR
T1 - Within-individual and interlaboratory variability analyses of urinary metabolites measurements of organophosphorus insecticides
AU - Ito, Yuki
AU - Ueyama, Jun
AU - Nakayama, Shoji F.
AU - Isobe, Tomohiko
AU - Oya, Naoko
AU - Sato, Hirotaka
AU - Ebara, Takeshi
AU - Yoshimasu, Kouichi
AU - Tsuno, Kanami
AU - Tatsuta, Nozomi
AU - Nakai, Kunihiko
AU - Kamijima, Michihiro
PY - 2020/7/1
Y1 - 2020/7/1
N2 - 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.
AB - 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.
KW - Biomonitoring
KW - Interlaboratory variability
KW - Organophosphorus insecticides
KW - Urine
KW - Within-individual variability
UR - http://www.scopus.com/inward/record.url?scp=85061100525&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85061100525&partnerID=8YFLogxK
U2 - 10.1038/s41370-019-0124-7
DO - 10.1038/s41370-019-0124-7
M3 - Article
AN - SCOPUS:85061100525
VL - 30
SP - 721
EP - 729
JO - Journal of Exposure Science and Environmental Epidemiology
JF - Journal of Exposure Science and Environmental Epidemiology
SN - 1559-0631
IS - 4
ER -