Science Inventory

Recommendations for Advancing Test Protocols Examining the Photo-induced Toxicity of Petroleum and Polycyclic Aromatic Compounds

Citation:

Alloy, M., B. Finch, C. Ward, A. Redman, A. Bejarano, AND M. Barron. Recommendations for Advancing Test Protocols Examining the Photo-induced Toxicity of Petroleum and Polycyclic Aromatic Compounds. AQUATIC TOXICOLOGY. Elsevier Science Ltd, New York, NY, 256:106390, (2023). https://doi.org/10.1016/j.aquatox.2022.106390

Impact/Purpose:

The purpose of this article is to summarize the state of the science on phototoxicity testing, and provide recommendations to advancing the science and making toxicity results more useful. The paper is the product of an international workgroup lead by the Canadian Department of Fisheries and Oceans. The impact of the work is that phototoxicity is an important consideration in oil spill response and impact assessment because sunlight can substantially increase the aquatic toxicity of specific petroleum hydrocarbons (phenonenom known as phototoxicity). Developing better phototoxicity data will facilitate an understanding of oil toxicity in the environment and may provide for more informed spill response decisions and assessments. The presentation will provide conference participants a succinct overview of mechanisms of toxicity, which are not widely understood or appreciated. The impact of this presentation is three fold: (1) It will communicate that dogma concerning a single minimal toxicity mechanism is not sufficient in assessing the impacts of oil spills. (2) It will show that EPA scientists are leaders in the field of oil toxicology, which is significant for future testimony as an expert witness. (3) It provides an opportunity to interact with other scientists and exchange information.

Description:

Photo-induced toxicity of petroleum products and polycyclic aromatic compounds (PACs) is the enhanced toxicity caused by their interaction with ultraviolet radiation 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 which did not address phototoxicity. 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 photosensitization (change in compound energy state) and photomodification (change in compound structure) are addressed separately, and practical applications in laboratory and field studies and predictive model development 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. Recommendations are provided to promote greater standardization of laboratory studies on photo-induced toxicity to further advance comparisons across studies and to highlight the connection of these data types and study conditions to the models used in oil spill assessments.