Optical properties of rainbow trout lenses after in vitro exposure to polycyclic aromatic hydrocarbons in the presence or absence of ultraviolet radiation.

The optical properties of rainbow trout lenses were investigated after in vitro exposure to polycyclic aromatic hydrocarbons (PAHs) and ultraviolet (UV) irradiation, both because PAHs frequently contaminate aquatic environments and because UV exposure has generally increased with the decline of the ozone layer. Lenses were exposed to UV irradiation for 12 hr while immersed in culture medium. UV irradiation, with or without the presence of PAHs, was accomplished with one UVA and one UVB photoreactor lamp to yield a photon fluence rate of 9.27 micromol m(-2)s(-1)UVA (UVA:UVB 10.8, radiant exposure of 13.4 Jcm(-1)). Individual PAHs studied were fluorene, fluoranthene and benzo(a)pyrene. In addition, lenses were exposed to a solution of creosote, a wood preservative used in the aquatic environment that contains many PAHs. All PAH exposures, including creosote, were carried out either in the dark or concurrently with UV irradiation. A scanning laser monitor system was used to evaluate the optical properties of lenses for up to 236 hr after the UV/PAH treatments. Mean focal length variability (FLV) increased with time after concurrent exposure to UV irradiation and high concentrations of either fluoranthene (4900 n m), benzo(a)pyrene (265 n m) or creosote (70 microg ml(-1)), with FLV values ranging from, 0.21-0.41, 0.21-0.64 and 0.15-0.22 mm, respectively, 72 hr after termination of the UV/PAH treatment. UV irradiation alone or exposure to PAHs in the dark brought about no changes in the optical properties of lenses. Also, fluorene in the presence or absence of UV had no effect, even at concentrations as high as 128 microm. Lenses were also unchanged by 12 hr exposures in the dark to solutions of either fluorene, fluoranthene, benzo(a)pyrene or creosote that had been previously UV irradiated for 12 hr. This meant that photomodified products of the individual PAHs or creosote were not cataractogenic and emphasized that simultaneous exposure to UV and PAHs or creosote was necessary for the increased FLV. The results point for the first time to an interaction between UV irradiation and PAHs as a potential contributing factor to cataract formation in fish. Copyright 2000 Academic Press.