Background

Several studies have found associations between increases in QT interval length, a marker of cardiac electrical instability, and short-term fine particulate matter (PM_2.5) exposures. To our knowledge, this is the first study to examine the association between specific PM_2.5 metal components and QT interval length.

Methods

We measured heart-rate corrected QT interval (QTc) duration among 630 participants in the Normative Aging Study (NAS) based in Eastern Massachusetts between 2000 and 2011. We utilized time-varying linear mixed-effects regressions with a random intercept for each participant to analyze associations between QTc interval and moving averages (0–7 day moving averages) of 24-h mean concentrations of PM_2.5 metal components (vanadium, nickel, copper, zinc and lead) measured at the Harvard Supersite monitoring station. Models were adjusted for daily PM_2.5 mass estimated at a 1 km × 1 km grid cell from a previously validated prediction model and other covariates. Bayesian kernel machine regression (BKMR) was utilized to assess the overall joint effect of the PM_2.5 metal components.

Results

We found consistent results with higher lead (Pb) associated with significant higher QTc intervals for both the multi-pollutant and the two pollutant (PM_2.5 mass and a PM_2.5 component) models across the moving averages. The greatest effect of lead on QTc interval was detected for the 4-day moving average lead exposure. In the multi-pollutant model, each 2.72 ng/m³ increase in daily lead levels for a 4-day moving average was associated with a 7.91 ms (95% CI: 3.63, 12.18) increase in QTc interval. In the two-pollutant models with PM_2.5 mass and lead, each 2.72 ng/m³ increase in daily lead levels for a 4-day moving average was associated with an 8.50 ms (95% CI: 4.59, 12.41) increase in QTc interval. We found that 4-day moving average of copper has a negative association with QTc interval when compared to the other PM_2.5 metal components. In the multi-pollutant model, each 1.81 ng/m³ increase in daily copper levels for a 4-day moving average was associated with an −3.89 ms (95% CI: -6.98, −0.79) increase in QTc interval. Copper's essential function inside the human body could mediate its cardiotoxicity on cardiac conductivity and explain why we found that copper in comparison to the other metals was less harmful for QTc interval.

Conclusions

Exposure to metals contained in PM_2.5 are associated with acute changes in ventricular repolarization as indicated by QT interval characteristics.

中文翻译：

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规范老化研究中 PM2.5 金属成分与 QT 间期长度之间的关联

 背景

多项研究发现，QT 间期长度（心脏电不稳定的标志）的增加与短期细颗粒物 (PM _2.5 ) 暴露之间存在关联。据我们所知，这是第一项研究特定 PM _2.5金属成分与 QT 间期长度之间关系的研究。

 方法

我们测量了 2000 年至 2011 年间在马萨诸塞州东部进行的规范衰老研究 (NAS) 中 630 名参与者的心率校正 QT 间期 (QTc) 持续时间。我们利用时变线性混合效应回归，对每个参与者进行随机截距分析 QTc 间隔与哈佛 Supersite 监测站测量的 PM _2.5金属成分（钒、镍、铜、锌和铅）24 小时平均浓度的移动平均值（0-7 天移动平均值）之间的关联。根据先前验证的预测模型和其他协变量在 1 km × 1 km 网格单元中估计的每日 PM _2.5质量对模型进行了调整。利用贝叶斯核机器回归 (BKMR) 来评估 PM _2.5金属成分的整体联合效应。

 结果

我们发现，对于跨移动平均值的多污染物和两种污染物（PM _2.5质量和 PM _2.5成分）模型，较高的铅 (Pb) 与显着较高的 QTc 间隔相关，结果一致。在 4 天移动平均铅暴露中检测到铅对 QTc 间期的影响最大。在多污染物模型中，4 天移动平均值的日铅水平每增加 2.72 ng/m ³ ，QTc 间期就会增加 7.91 ms (95% CI: 3.63, 12.18)。在 PM _2.5质量和铅的两种污染物模型中，4 天移动平均值的每日铅水平每增加 2.72 ng/m ³与 QTc 间期增加 8.50 ms (95% CI: 4.59, 12.41) 相关。我们发现，与其他 PM _2.5金属成分相比，铜的 4 天移动平均线与 QTc 间隔呈负相关。在多污染物模型中，4 天移动平均值的每日铜水平每增加 1.81 ng/m ³ ，与 QTc 间期增加 -3.89 ms（95% CI：-6.98，-0.79）相关。铜在人体内的基本功能可以介导其对心脏电导率的心脏毒性，并解释了为什么我们发现与其他金属相比，铜对 QTc 间期的危害较小。

 结论

QT 间期特征表明，接触 PM _2.5中所含的金属与心室复极的急剧变化相关。