Systematic Review and Meta-Analysis on the Impact of Polycyclic Aromatic Hydrocarbons Exposure in Cognitive Function and Neurodegeneration in Humans

Abstract

Exposure to air pollution is now recognized globally by governments, leading research scientists, and civil society as one of the greatest public health hazards of the 21st century. Polycyclic aromatic hydrocarbons (PAH) are a group of air pollutants discharged mainly from incomplete combustion and pyrolysis of hydrocarbons, predominantly found in: coal, oil, wood and petrol. PAH exist in the atmosphere in a gaseous state or adsorbed to particulate matter, mainly of 2.5mm diameter or less (PM2.5). Given the anthropogenic nature of PAH sources and their small size, they are difficult to regulate and account for, but their exposure has been associated with worsening asthma, coronary heart disease, various types of cancers, decreased immune function and organ damage. However, their implications on cognitive functions and neuronal health in humans has not been systematically recorded/analysed up to date as only sporadic studies have been conducted in few countries. This submission contains the results of the systematic search, data extraction and meta-analyses from systematically reviewing the existent literature on the impact of PAH exposure in cognitive function and neurodegeneration in humans. The data is contained in two excel spreadsheets. One spreadsheet contains details of the search (i.e., search strategy, keywords, databases, search results, included references, excluded references with reasons for exclusion, and duplicates). The other spreadsheet contains the data extracted from analysing the papers reviewed (i.e., included), and the meta-analyses (multi-variable graphs and forest plots with their sources). Worksheets not containing meta-analyses are also provided in csv (comma delimited) format.