Recommendations for advancing test protocols examining the photo-induced toxicity of petroleum and polycyclic aromatic compounds

Photo-induced toxicity of petroleum products and polycyclic aromatic compounds (PACs) is the enhanced toxicity caused by their interaction with ultraviolet ra-diation and occurs by two distinct mechanisms: photosensitization and photomodification. Laboratory approaches for designing, conducting, and reporting of photo -induced toxicity studies are reviewed and recommended to enhance the original Chemical Response to Oil Spills: Ecological Research Forum (CROSERF) protocols which did not address photo-induced toxicity. Guidance is provided on conducting photo-induced toxicity tests, including test species, endpoints, experimental design and dosing, light sources, irradiance measurement, chemical characterization, and data reporting. Because of distinct mechanisms, aspects of photosensiti-zation (change in compound energy state) and photomodification (change in compound structure) are addressed separately, and practical applications in laboratory and field studies and advances in predictive modeling are discussed. One goal for developing standardized testing protocols is to support lab-to-field extrapolations, which in the case of petroleum substances often requires a modeling framework to account for differential physicochemical properties of the constituents. Rec-ommendations are provided to promote greater standardization of laboratory studies on photo-induced toxicity, thus facilitating comparisons across studies and generating data needed to improve models used in oil spill science.

Automated summary

Photo-induced toxicity of petroleum products and PACs is enhanced by interaction with ultraviolet radiation through photosensitization and photomodification mechanisms. This article reviews and recommends laboratory approaches for conducting photo-induced toxicity studies, providing guidance on test species, endpoints, experimental design, dosing, light sources, irradiance measurement, chemical characterization, and data reporting. The importance of standardized testing protocols, practical applications, and predictive modeling in oil spill science is discussed.