Distribution and elimination of naphthalene and 2-methylnaphthalene in rainbow trout during short- and long-term exposures

Abstract

The accumulation and elimination of¹⁴C in rainbow trout tissues following short- and long-term exposures to aqueous¹⁴C-naphthalene or^14C-2-methylnaphthalene were studied. After exposure for eight hr to 0.005 mg/L or 0.023 mg/L of¹⁴C-naphthalene most tissues of fingerling rainbow trout studied contained¹⁴C at 20 to 100 times the water levels while fat and bile contained¹⁴C at several hundred times water levels. The half-lives for elimination of¹⁴C from all tissues except fat were less than 24 hr. Exposure of fingerling rainbow trout to¹⁴C-naphthalene or¹⁴C-2-methylnaphthalene for four weeks in a continuous-flow delivery system resulted in maximum tissue levels of these chemicals of from 40 to 300 times the water concentration. Maximum bile¹⁴C levels were 13,000 and 23,500 times the water concentration for¹⁴C-naphthalene and¹⁴C-2-methylnaphthalene exposure, respectively. Elimination of¹⁴C accumulated from¹⁴C-naphthalene in this long-term exposure was much slower than after short-term exposures, while elimination of¹⁴C accumulated from¹⁴C-2-methylnaphthalene was biphasic. The presence of parent compounds and metabolites in acetone extracts of muscles was determined by TLC. The data suggest that the biphasic release of¹⁴C from muscle of trout exposed to¹⁴C-2-methylnaphthalene may be due to differential elimination of parent compound and metabolites.