Intra-individual variations of organophosphate pesticide metabolite concentrations in repeatedly collected urine samples from pregnant women in Japan

Abstract

BackgroundLow-dose exposure to organophosphate (OP) insecticides during pregnancy may adversely affect neurodevelopment in children. To evaluate the OP exposure levels, single urine sampling is commonly adopted to measure the levels of dialkylphosphates (DAPs), common OP metabolites. However, the inter-day variations of urinary DAP concentrations within subjects are supposed to be large due to the short biological half-lives of the metabolites, and it is thus considered difficult to accurately assess OP exposure during pregnancy with single sampling. This study aimed to assess intra-individual variations of DAP concentrations and the reproducibility of the exposure dose categorization of OPs according to DAP concentration ranges in pregnant women in Japan.MethodsUrine samples were collected from 62 non-smoking pregnant women (12–22 weeks of gestation) living in Aichi Prefecture, Japan. First morning void (FMV) and spot urine samples taken between lunch and dinner on the same day were collected on five different days during 2 weeks. The concentrations of DAP and creatinine in urine samples were measured using an ultra performance liquid chromatography with tandem mass spectrometry. Creatinine-adjusted and unadjusted concentrations were used for the intraclass correlation coefficient (ICC) calculations and surrogate category analyses.ResultsFor all DAP metabolites, the creatinine-adjusted single ICCs exceeded 0.4, indicating moderate reliability. Overall, ICCs of spot urine samples taken in the afternoon were better than those taken as FMV. Surrogate category analyses showed that participants were categorized accurately into four exposure dose groups according to the quartile points.ConclusionThis study indicated that a single urine sample taken in the afternoon may be useful in assessing OP exposure as long as the exposure is categorized into quartiles when conducting epidemiological studies in early to mid-pregnant women in Japan.Electronic supplementary materialThe online version of this article (10.1186/s12199-019-0761-4) contains supplementary material, which is available to authorized users.

Urinary Metabolites of Organophosphate Pesticides among Pregnant Women Participating in the Japan Environment and Children’s Study (JECS)

“…To the best of our knowledge, this is the first study to investigate urinary DAP concentrations of Japanese pregnant women on this scale. Urinary DAP concentrations were comparable with those in another Japanese study [ 21 ] and in previous studies from other countries [ 3 , 6 , 48 , 49 , 50 , 51 , 52 ]. In this study, strict QC measures were employed such as reproducibility, repeatability (intermediate precision), blank test, linearity of the calibration curves, duplicated measurements, recovery of IS samples, target ion/qualifier ion ratio and external QC.…”

“…Urinary metabolites of OPPs, i.e., DAPs, have short half-lives ranging from 2 to 15.5 h [ 17 , 18 ]. One study on Japanese pregnant women reported intra-class correlation coefficients (ICCs) to be 0.42–0.55 [ 21 ], while studies conducted in other countries provided −0.01–0.52 [ 51 , 56 , 57 , 58 ]. According to the rule of thumb, an ICC of 0.4 is categorised as “moderate” [ 59 ].…”

“…There are no nationally representative biomonitoring data for OPPs in Japan. A few studies conducted in the last five years showed that metabolites of OPPs were detected in Japanese women and children [ 14 , 20 ], including pregnant women [ 21 ].…”

Impact of Pesticide Exposure among Rural and Urban Female Population. An Overview

“…Similar studies have been carried out in different countries, so in comparison to these levels of DAP, they were slightly higher than the ones from the Columbia Center for Children’s Environmental Health, another NYC-based cohort [ 47 ]. These levels were lower than for most European and Asian cohorts [ 48 , 49 ]. Many authors tried to associate the increase of these levels of DAP with vegetable and meat intake.…”

Organophosphate Pesticide Exposure and Breast Cancer Risk: A Rapid Review of Human, Animal, and Cell-Based Studies

“…While biomonitoring provides a rough estimate, it is often considered a more biologically accurate way of measuring OP exposure. Future studies should consider using the highly specific method of gas chromatography coupled with tandem mass spectrometry for biomonitoring [ 80 , 81 , 82 ].…”