Institute for Risk Assessment Sciences (IRAS), Utrecht University, Utrecht, the Netherlands.
Barcelona Institute for Global Health (ISGlobal), Doctor Aiguader 88, 08003, Barcelona, Spain; Universitat Pompeu Fabra (UPF), Doctor Aiguader 88, 08003, Barcelona, Spain; CIBER Epidemiología y Salud Pública (CIBERESP), Melchor Fern'andez Almagro, 3-5, 28029, Madrid, Spain.
Environ Res. 2024 Dec 15;263(Pt 3):120215. doi: 10.1016/j.envres.2024.120215. Epub 2024 Oct 22.
Health Impact Assessments (HIAs) for air pollutant mixtures are challenging because risk estimates are primarily derived from single-pollutant models. Combining risk estimates from multiple pollutants requires new approaches, as a simple addition of single pollutant risk estimates from correlated air pollutants may result in double counting. We investigated approaches applying concentration-response functions (CRFs) from single- and two-pollutant models in HIAs, focusing on long-term exposure to particulate matter with a diameter less than 2.5 μm (PM) and nitrogen dioxide (NO) and their associations with all-cause mortality.
A systematic literature search of MEDLINE and EMBASE identified cohort studies employing single- and two-pollutant models of long-term exposure to PM and NO with all-cause mortality. Pooled CRFs were calculated through random-effects meta-analyses of risk estimates from single- and two-pollutant models. Coefficient differences were calculated by comparing single- and two-pollutant model estimates. Four approaches to estimating population-attributable fractions (PAFs) were compared: PM or NO single-pollutant models to represent the mixture, the sum of single-pollutant models, the sum of two-pollutant models and the sum of single-pollutant models from a larger body of evidence adjusted by coefficient difference.
Seventeen papers reported both single and two-pollutant estimates. Pooled hazard ratios (HRs) for mortality from single- and two-pollutant models were 1.053 (95% confidence interval: 1.034-1.071) and 1.035 (1.014-1.057), respectively, for a 5 μg/m increase in PM. HRs for a 10 μg/m increase in NO were 1.032 (1.014-1.049) and 1.024 (1.000-1.049) for single- and two-pollutant models, respectively. The average coefficient difference between single- and two-pollutant models was 0.017 for PM and 0.007 for NO. Combined PAFs for the PM-NO mixture using joint HRs from single- and two-pollutant model CRFs were 0.09 and 0.06, respectively.
Utilizing CRFs from two-pollutant models or applying the coefficient difference to a more extensive evidence base seems to mitigate the potential overestimation of mixture health impacts from adding single-pollutant CRFs.
由于风险估计主要源自单污染物模型，因此对空气污染物混合物进行健康影响评估（HIA）具有挑战性。要合并来自多种污染物的风险估计值，需要采用新的方法，因为简单地将来自相关空气污染物的单污染物风险估计值相加，可能会导致重复计算。我们研究了在 HIA 中应用单污染物和双污染物模型的浓度-反应函数（CRF）的方法，重点是长期暴露于直径小于 2.5μm 的颗粒物（PM）和二氧化氮（NO）及其与全因死亡率的关系。
通过对 MEDLINE 和 EMBASE 进行系统的文献检索，确定了采用单污染物和双污染物模型长期暴露于 PM 和 NO 与全因死亡率的队列研究。通过对单污染物和双污染物模型的风险估计值进行随机效应荟萃分析，计算了合并的 CRF。通过比较单污染物和双污染物模型的估计值，计算了系数差异。比较了四种估计人群归因分数（PAF）的方法：PM 或 NO 单污染物模型来代表混合物，单污染物模型的总和，双污染物模型的总和以及由更大的证据体调整系数差异后的单污染物模型的总和。
有 17 篇论文报告了单污染物和双污染物的估计值。PM 浓度每增加 5μg/m，单污染物和双污染物模型的死亡率的合并危害比（HR）分别为 1.053（95%置信区间：1.034-1.071）和 1.035（1.014-1.057）。NO 浓度每增加 10μg/m，单污染物和双污染物模型的 HR 分别为 1.032（1.014-1.049）和 1.024（1.000-1.049）。PM 和 NO 的单污染物和双污染物模型之间的平均系数差异分别为 0.017 和 0.007。使用单污染物和双污染物模型的 CRF 的联合 HR 计算 PM-NO 混合物的综合 PAF 分别为 0.09 和 0.06。
利用双污染物模型的 CRF 或应用系数差异到更广泛的证据基础，似乎可以减轻因添加单污染物 CRF 而导致的混合物健康影响的潜在高估。
