In Vitro Toxicity Assessment of Tire-related Chemicals in Cells from Diverse Fish Species

Urban stormwater runoff introduces tire‑related contaminants such as 6PPD‑quinone (6PPD‑Q), which has been shown to exhibit acute toxicity in some salmonid species, although the underlying toxic mechanisms remain incompletely understood. To expand in vitro toxicological assessments, we evaluated the cytotoxicity of 3,4‑dichloroaniline and 6PPD‑quinone using six fish‑derived cell lines from salmonids and phylogenetically distant species, based on nominal concentrations at the time of addition. Among these cell lines, CSE‑119 cells, which are derived from coho salmon, exhibited the highest sensitivity to 6PPD‑quinone (EC₅₀ = 8.54 µg/L), demonstrating pronounced species‑specific differences in sensitivity to quinone‑type toxicants and underscoring the value of comparative in vitro models. Using multiple fish cell lines enables the efficient, animal‑welfare-conscious screening of tire‑associated chemicals. However, further investigation is needed into evaluation methods that take into account factors such as the stability of chemicals in the culture medium.