Applicability of in vitro methods in evaluating the biotransformation of polycyclic aromatic hydrocarbons (PAHs) in fish: Advances and challenges

The biotransformation of polycyclic aromatic hydrocarbons (PAHs) and the biochemical mechanisms involved in such process continue to be intensively studied in the fields of environmental science and toxicology. The investigation of PAH biotransformation in fish is fundamental to understand how piscine species cope with PAH exposure, as these compounds are ubiquitous in aquatic ecosystems and impact different levels of biological organization. New approaches are continuously developed in the field of ecotoxicology, allowing live animal testing to be combined with and, in some cases, replaced with novel in vitro systems. Many in vitro techniques have been developed and effectively applied in the investigation of the biochemical pathways driving the biotransformation of PAH in fish. In vitro experimentation has been fundamental in the advancement of not only understanding PAH-mediated toxicity, but also in highlighting suitable cell-based models for such investigations. Therefore, the present review highlights the value and applicability of in vitro systems for PAH biotransformation studies, and provides up-to-date information on the use of in vitro fish models in the evaluation of PAH biotransformation, common biomarkers, and challenges encountered when developing and applying such systems.