Department of Occupational and Environmental Health, Nagoya City University Graduate School of Medical Sciences, Nagoya, 467-8601, Japan.
Center for Health and Environmental Risk Research, National Institute for Environmental Studies, Tsukuba, 305-8506, Japan.
Environ Health Prev Med. 2019 Jan 17;24(1):7. doi: 10.1186/s12199-019-0761-4.
Low-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.
Urine 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.
For 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.
This 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.
孕期低剂量接触有机磷（OP）杀虫剂可能对儿童的神经发育产生不利影响。为了评估 OP 暴露水平，通常采用单次尿样采集来测量二烷基磷酸酯（DAP）的水平，DAP 是常见的 OP 代谢物。然而，由于代谢物的生物半衰期较短，受试者内尿液 DAP 浓度的日内变化应该很大，因此单次采样很难准确评估孕期 OP 暴露情况。本研究旨在评估日本孕妇 DAP 浓度的个体内变异以及根据 DAP 浓度范围对 OP 暴露剂量进行分类的重现性。
采集了来自日本爱知县的 62 名不吸烟孕妇（妊娠 12-22 周）的尿液样本。在两周内的 5 天内，采集了 5 天不同日期的 12-22 孕周的非吸烟孕妇晨尿（FMV）和当天午餐至晚餐之间采集的随机尿样。使用超高效液相色谱-串联质谱法测量尿液样本中 DAP 和肌酐的浓度。使用尿肌酐调整和未调整的浓度进行组内相关系数（ICC）计算和替代类别分析。
对于所有 DAP 代谢物，尿肌酐调整后的单 ICC 均超过 0.4，表明具有中度可靠性。总体而言，下午采集的随机尿样的 ICC 优于 FMV 采集的尿样。替代类别分析表明，根据四分位数点，参与者可以准确地分为四个暴露剂量组。
本研究表明，在日本孕早期至中期进行流行病学研究时，只要将暴露分为四分位数，下午采集的单次尿样可能有助于评估 OP 暴露情况。
