Polycyclic aromatic hydrocarbons contamination in Amazonian environments: a systematic review

The Amazon River has become contaminated with organic pollutants, such as polycyclic aromatic hydrocarbons (PAHs). This systematic review aimed to evaluate environmental samples, including water, sediment, and biological matrices, as monitoring tools for determining PAHs concentrations within the Amazon ecosystem. A comprehensive literature search was conducted across four databases (PubMed, ScienceDirect, Web of Science, and Scopus) from January 2013 to June 2024, resulting in 25 studies meeting the inclusion criteria. The systematic review revealed widespread significant contamination of PAHs in the Amazon, with sediments being the most affected matrix. Ecuador's Aguarico and Napo River basins showed the highest PAH levels, linked to extensive oil extraction activities, while Brazil's São Raimundo Harbor and Barcarena also exhibited high contamination due to industrial and fossil fuel activities. The PAHs values found in water range from 4 to 5,363,000 ng L^-1. The PAHs values in sediment range from 5 to 711,100 ng L^-1. For PAHs in urine, values ranged from 0.31 to 0.50 µmol mol^-1 creatinine. Biomarkers in species like Sciades herzbergii revealed oxidative stress and genotoxic effects, demonstrating the ecological impacts of PAHs in Amazonian ecosystems. However, direct health risk data for humans and terrestrial fauna remain limited and were not the focus of this review. The uneven geographical distribution of research, with Brazil representing 84% (21 of 25 studies) of the literature, emphasizes the need for expanded investigations in underrepresented areas of the Amazon.