1. Acute lethal toxicity of chloramines in some life stages of zebrafish (embryo, larva and adult).
Thee chloramines, ammonia chloramine (NHィイD22ィエD2Cl) (I), ethanolamine choloramine (II) and creatinine chloramine (III), were prepared and applied to acute lethal toxicity tests in embryo (8-9 hours after spawn), larva (3 or 4 days after hatch) and adults (6 month old). In embryos, EC50 (3 h) values of (I), (II), (III) and hypochlorous acid (HOCl) were 3.85, 4.04, 2.07 and 6.34 mg/L, respectively. The whitening of embryos proceeded after the transfer of them to clean water. These EC50 values after 24 h reduced to about 50% of 3 h. Delay of time for hatch was observed in the HOCl exposure. In larvae, EC50 (3h) values of (I), (III) and HOCl were 0.66, 2.00 and <0.20 mg/L, respectively. In adults, the tolerance for (I) was as well as that in larvae, but for HOCl, it was increased slightly.
2. Cytotoxicities of chloramines in cultured cells (BALB/3T3).
Cytotoxicities of ammonia chloramine (I), creatinin chloramine (III) and HOCl were determined from colony forming ability in cultured cells (BALB/3T3). The exposure medium was exchanged to Hanks solution in order to reduce side actions between chloramines and culture medium containing bovine serum. The concentration and time for 50% reduction of colony forming ability of (I) were 0.36 mg/L and 2 min. These of (III) and HOCl were 4.2 mg/L and 7 min and 1.42 mg/L and 5 min, respectively. In HOCl, side reactions between HOCl and cell components seemed to have effects on the extension of concentration and time.
These obtained results may give a fundamental information to the evaluation of residual chloramines effects on aquatic life.