Hazard assessment of oil spill response chemical herding agents to commercially valuable North Atlantic species.

This article focuses on the acute toxicity assessment of two herding agents, Siltech OP-40 (OP-40) and ThickSlick 6535 (TS6535), which are approved by the U.S. Environmental Protection Agency for use in oil spill response to reduce oil slick surface area. Toxicity tests were conducted on early life stages of four commercially important North Atlantic marine species: green sea urchin (Strongylocentrotus droebachiensis), American lobster (Homarus americanus), Atlantic cod (Gadus morhua), and lumpfish (Cyclopterus lumpus). Results showed that OP-40 is consistently more toxic—by factors ranging from 4 to 78—than TS6535 across species and endpoints, with toxicity values generally exceeding the concentrations expected in the environment after herder application. These findings provide hazard data to inform regulatory decisions and spill response strategies, emphasizing the need to balance efficacy with ecological risk, especially given limited knowledge on chronic effects and environmental persistence.