This investigation aimed to conduct a systematic review of the literature and meta-analysis to determine whether exposure to the herbicide paraquat was associated with the development of Parkinson's disease (PD). Observational studies that enrolled adults exposed to paraquat with PD as the outcome of interest were searched in the PubMed, Embase, LILACS, TOXNET, and Web of Science databases up to May 2019. Two authors independently selected relevant studies, extracted data, and assessed methodological quality. The evidence certainty was assessed by the GRADE approach, which served as basis for a tentative causality assessment, supplemented by the Bradford Hill criteria when necessary. Results from nine case-control studies indicated that PD occurrence was 25% higher in participants exposed to paraquat. The only cohort investigation included demonstrated a non-significant OR of 1.08. Results from subgroup analyses also indicated higher PD frequency in participants that were exposed to paraquat for longer periods or individuals co-exposed with paraquat and any other dithiocarbamate. Data indicate apositive association between exposure to paraquat and PD occurrence, but the weight-of-evidence does not enable one to assume an indisputable cause-effect relationship between these two conditions. Better designed studies are needed to increase confidence in results. Systematic Review Registration: PROSPERO CRD42017069994.

中文翻译：

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百草枯和帕金森氏病：对观察性研究的系统评价和荟萃分析。

这项调查旨在对文献和荟萃分析进行系统的审查，以确定暴露于除草剂百草枯是否与帕金森氏病（PD）的发生有关。截止至2019年5月，在PubMed，Embase，LILACS，TOXNET和Web of Science数据库中搜索了纳入百草枯暴露于百草枯的成年成年人的观察性研究。两名作者独立选择了相关研究，提取了数据并评估了方法学质量。证据的确定性是通过GRADE方法进行评估的，GRADE方法是暂时性因果关系评估的基础，必要时可以补充Bradford Hill标准。九项病例对照研究的结果表明，暴露于百草枯的参与者中PD的发生率高出25％。唯一的队列研究包括1.08的非显着OR。亚组分析的结果还表明，长期接触百草枯或与百草枯和任何其他二硫代氨基甲酸酯共同暴露的个体，其PD频率较高。数据表明百草枯的暴露与PD的发生之间存在积极联系，但证据权重不能使人们假设这两种情况之间存在无可争辩的因果关系。需要更好设计的研究来增加对结果的信心。系统评价注册：PROSPERO CRD42017069994。亚组分析的结果还表明，长期接触百草枯或与百草枯和任何其他二硫代氨基甲酸酯共同暴露的个体，其PD频率较高。数据表明百草枯的暴露与PD的发生之间存在积极联系，但证据权重不能使人们假设这两种情况之间存在无可争辩的因果关系。需要更好设计的研究来增加对结果的信心。系统评价注册：PROSPERO CRD42017069994。亚组分析的结果还表明，长期接触百草枯或与百草枯和任何其他二硫代氨基甲酸酯共同暴露的个体，其PD频率较高。数据表明百草枯的暴露与PD的发生之间存在积极联系，但证据权重不能使人们假设这两种情况之间存在无可争辩的因果关系。需要更好设计的研究来增加对结果的信心。系统评价注册：PROSPERO CRD42017069994。