Background

Spot urine samples are often used to assess exposure to organophosphate (OP) pesticides in place of “gold standard” 24-hr samples, which are cumbersome to collect. Assessment of non-persistent chemicals using spot urine samples may result in exposure misclassification that could bias epidemiological analyses towards the null. Few studies have examined the validity of measurements of urinary metabolites in spot samples to estimate daily OP dose or the potential implications of reliance on spot samples for risk assessments.

Objective

Examine the validity of using first morning void (FMV) and random non-FMV urine samples to estimate cumulative 24-hr OP pesticide dose among children living in an agricultural region.

Methods

We collected urine samples over 7 consecutive days, including two 24-hr samples, from 25 children living in an agricultural community. We used measurements of urinary dialkylphosphate (DAP) metabolites, data on nearby agricultural pesticide applications, and daily dietary intake data to estimate internal dose from exposure to a mixture of OP pesticides according to the U.S. Environmental Protection Agency Cumulative Risk Assessment guidelines. Dose estimates from volume- and creatinine-adjusted same-day FMV and non-FMV spot urine samples were compared to the “gold standard” estimates from 24-hr samples.

Results

Non-FMV samples had relatively weak ability to predict 24-hr dose (R² = 0.09–0.38 for total DAPs) and tended to underestimate the percentage of samples exceeding regulatory guidelines. Models with FMV samples or the average of an FMV and non-FMV sample were similarly predictive of 24-hr estimates (R² for DAPs = 0.40–0.68 and 0.40–0.80, respectively, depending on volume adjustment method).

Conclusion

Reliance on non-FMV samples for risk assessments may underestimate daily OP dose and the percentage of children with dose estimates exceeding regulatory guidelines. If 24-hr urine sample collection is infeasible, we recommend future studies prioritize the collection of FMV samples to most accurately characterize OP dose in children.

中文翻译：

---

根据从农业社区儿童中收集的当场和24小时尿液样本估算有机磷农药的剂量

背景

尿液现货样品通常用于评估有机磷（OP）农药的暴露水平，以代替“金标准” 24小时样品，这些样品很难收集。使用尿液样本对非持久性化学品进行评估可能会导致暴露分类错误，这可能会使流行病学分析偏向于无效。很少有研究检查了现场样本中尿液代谢物的测量方法的有效性，以估计每日OP剂量或依赖现场样本进行风险评估的潜在影响。

目的

检查使用第一个早晨排尿（FMV）和随机非FMV尿液样本估计居住在农业地区儿童中24小时OP农药累积剂量的有效性。

方法

我们连续7天收集了25个生活在农业社区中的儿童的尿液样本，包括两个24小时样本。根据美国环境保护署累积风险评估指南，我们使用了尿酸二烷基磷酸酯（DAP）代谢产物的测量值，附近农业杀虫剂应用的数据以及日常饮食摄入量数据，估算了因接触OP农药混合物而产生的内部剂量。将体积和肌酐调整后的当日FMV和非FMV现场尿液样本的剂量估计值与24小时样本的“黄金标准”估计值进行比较。

结果

非FMV样品的24小时剂量预测能力相对较弱（ 总DAP的R ² = 0.09-0.38），并且往往低估了超出监管准则的样品百分比。具有FMV样本或FMV和非FMV样本平均值的模型可以类似地预测24小时估算值（DAP的R ^2分别为0.40-0.68和0.40-0.80，这取决于体积调整方法）。

结论

依靠非FMV样本进行风险评估可能会低估每日OP剂量以及剂量估计超出监管准则的儿童的百分比。如果无法进行24小时尿液样本收集，我们建议以后的研究优先收集FMV样本，以最准确地表征儿童的OP剂量。