A review of the effects of benzo(α)pyrene on amphibians

Abstract

In this overview, we address both in vitro and in vivo studies involving amphibians and the environmental contaminant benzo(α)pyrene (BαP). We indentified 66 papers published between 1939 and 2025, encompassing 23 species – 16 from the order Anura and 7 from the order Caudata, with no studies on Gymnophiona. Across these studies, regardless of taxonomic group, amphibians exhibited rapid absorption and metabolism of BαP (within 24 h), leading to the formation of secondary metabolites such as diols, which act as precursors of carcinogenic compounds capable of inducing DNA strand breaks. Following these initial processes, anatomical, physiological, and ultrastructural changes begin to occur. The progression of effects typically starts with genetic damage (e.g. adducts, breaks, and mutations) which alter the expression of genes related to metabolism and cellular structures. Subsequent histopathological effects include pigmentary changes, tissue disorganization, and leukocyte infiltration, which, if persd leukocyte infiltration, which, if persistent, can lead to pathologies, malformations, and tumors. These effects may result in permanent damage that can be transmitted to subsequent generations. In addition to examining the biological effects of BαP, this overview also summarizes key methodological aspects of the reviewed papers, including exposure routes, concentration, dilution and duration of exposure. This work aims to serve as a valuable reference for future investigations, while also identifying knowledge gaps and guiding new experiments and research efforts.