Acute Toxicity of a Tire Rubber-Derived Chemical, 6PPD Quinone, to Freshwater Fish and Crustacean Species

N-(1,3-Dimethylbutyl)-N′-phenyl-p-phenylenediamine-quinone, also known as 6PPD quinone, was recently identified as a toxic chemical that causes acute mortality in coho salmon following exposure to urban runoff. Despite its potential occurrence in receiving waters worldwide, there is no information about the toxicity of 6PPD quinone to other aquatic species. In this study, to assess the aquatic toxicity of 6PPD quinone to freshwater fish and crustacean species, we performed standardized 48–96 h acute toxicity tests of 6PPD quinone with four species (Danio rerio, Oryzias latipes, Daphnia magna, and Hyalella azteca). In contrast to the high toxicity observed in coho salmon in a previous study (24 h LC50 of 0.79 μg/L), 6PPD quinone did not exhibit acute lethal toxicity to any species at its maximum water solubility. The absence of acute lethality of 6PPD quinone to tested species indicates that the urban runoff toxicity observed for the species can be attributed to other chemicals. The observed large discrepancy in toxicity (by a factor of ∼100) might be due to the specific toxicity of 6PPD quinone to coho salmon. Further research is needed to reveal the underlying mechanisms of the observed difference, which will be useful for both urban runoff management and aquatic toxicology.