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Sci Total Environ. 2017 Mar 1;581-582:66-79. doi: 10.1016/j.scitotenv.2016.09.207. Epub 2016 Oct 5.
Since Flint returned to its pre-crisis source of drinking water close to 25,000 water samples have been collected and tested for lead and copper in >10,000 residences. This paper presents the first analysis and time trend modeling of lead data, providing new insights about the impact of this intervention. The analysis started with geocoding all water lead levels (WLL) measured during an 11-month period following the return to the Detroit water supply. Each data was allocated to the corresponding tax parcel unit and linked to secondary datasets, such as the composition of service lines, year built, or census tract poverty level. Only data collected on residential parcels within the City limits were used in the analysis. One key feature of Flint data is their collection through two different sampling initiatives: (i) voluntary or homeowner-driven sampling whereby concerned citizens decided to acquire a testing kit and conduct sampling on their own (non-sentinel sites), and (ii) State-controlled sampling where data were collected bi-weekly at selected sites after training of residents by technical teams (sentinel sites). Temporal trends modeled from these two datasets were found to be statistically different with fewer sentinel data exceeding WLL thresholds ranging from 10 to 50μg/L. Even after adjusting for housing characteristics the odds ratio (OR) of measuring WLL above 15μg/L at non-sentinel sites is significantly >1 (OR=1.480) and it increases with the threshold (OR=2.055 for 50μg/L). Joinpoint regression showed that the city-wide percentage of WLL data above 15μg/L displayed four successive trends since the return to Detroit Water System. Despite the recent improvement in water quality, the culprit for differences between sampling programs needs to be identified as it impacts exposure assessment and might influence whether there is compliance or not with the Lead and Copper Rule.
自弗林特（Flint）恢复使用其危机前的饮用水源以来，已采集并测试了超过 10000 个住宅的近 25000 个水样，以检测铅和铜的含量。本文首次分析和建立时间趋势模型，以提供有关这项干预措施影响的新见解。分析从测量自返回底特律供水系统后的 11 个月内所有饮用水中的铅水平（WLL）开始。每个数据都被分配到相应的税区单元，并与二次数据集（例如服务线路的组成、建造年份或普查区贫困水平）相关联。仅使用城市范围内住宅地段收集的数据进行分析。弗林特数据的一个关键特征是通过两个不同的采样计划进行收集：（i）自愿或房主驱动的采样，即有关公民决定自行购买测试套件并进行采样（非哨点），以及（ii）州控制采样，在技术团队培训居民后，每周在选定地点收集数据（哨点）。从这两个数据集建模的时间趋势被发现存在统计学差异，较少的哨点数据超过 10 至 50μg/L 的 WLL 阈值。即使在调整住房特征后，非哨点测量的 WLL 超过 15μg/L 的比值比（OR）仍然显著>1（OR=1.480），且随着阈值的增加而增加（OR=2.055 对于 50μg/L）。连接点回归显示，自底特律供水系统恢复以来，全市超过 15μg/L 的 WLL 数据百分比显示出四个连续趋势。尽管最近水质有所改善，但仍需确定采样计划之间差异的原因，因为这会影响暴露评估，并可能影响是否符合《铅和铜规则》。
