Quantification of two aromatic amine mutagens, PBTA-1 and PBTA-2, in the Yodo River system

The levels of two aromatic amine mutagens, 2-[2-(acetylamino)-4-[bis(2-meth oxyethyl)amino]-5-methoxlphenyl]-5-amino-7-bromo-4-chloro-2H-benzotriazole (PBTA-1) and 2-[2-(acetylamino-4-[N-(2-cyanoethyl)ethylamino]-5-methoxyphen yl]-5-amino-7-bromo-4-chloro-2H-benzotriazole (PBTA-7), were quantitatively analyzed in the Yodo River system in Japan. The river water samples were c ollected at nine sampling sites from the Yodo River system twice or three t imes between May and July in 1997. PBTA-1 and PBTA-2 in the river water sam ples were concentrat ed on blue rayon columns, partially purified by high-p erformance liquid chromatography (HPLC) on reverse-phase columns, then quan tified by HPLC with an electrochemical detector. The amounts of PBTA-1 and PBTA-2 in the water samples were < 0.01-1.91 and < 0.01-2.25 ng/L, respecti vely. High levels of PBTA-1 and PBTA-2 were detected in the samples collect ed within 4 km downstream of two sewage plants, which are located along the banks of the Nishitakase River, a tributary of the Yodo River system, and these samples showed stronger mutagnicity in Salmonella typhimurium YG1024 with S9 mix than the other water samples. On the other hand, the river wate r samples from upstream of the sewage plant were weakly or nor mutagenic an d PBTA-1 and PBTA-2 were not detected. These results confirmed that a major source of PBTA-1 and PBTA-2 in the Yodo River system is effluent from the sewage plants and that discharged mutagens, including PBTA-1 and PBTA-2, ar e diluted and/or decomposed while moving downr the Yodo River system.