title: Effects of different protective agents on the phototoxicity of fluoranthene to Daphnia magna.
abstract: Some compounds, accumulated by organisms, are transformed into toxic forms when irradiated with UV light. The polycyclic aromatic hydrocarbon (PAH) fluoranthene is one such compound of environmental importance. In this study on Daphnia magna, fluoranthene toxicity increased significantly after a 2 h exposure to solar-simulating UV light, if organisms were allowed to accumulate the substance for 24 h prior to irradiation. Since no enhanced toxicity was observed if the solutions were irradiated before the daphnids were added and only a slight decrease in toxicity was observed if the daphnids were transferred to pure dilution water prior to exposure, it was concluded that the acute phototoxicity of fluoranthene was predominantly due to photoactivation of accumulated or adsorbed molecules. Thus, the enhanced toxicity of fluoranthene by UV light is thought to act through the production of either singlet oxygen or free radicals. Possible effects of different protective agents (antioxidants, free radical scavengers and UV-screening compounds) were examined in two cultured populations of Daphnia magna. One population received a synthetic diet and the other dried baker's yeast. The yeast-fed population became progressively more sensitive to the photoinduced toxicity of fluoranthene, and after 14 days it was significantly more sensitive than the population that received the synthetic feed. It was not obvious whether any of the additives influenced the UV-induced toxicity significantly, although, alpha-tocopherol, a known antioxidant, was the best candidate.
authors.affiliation: Department of Applied Environmental Science, University of Gothenburg, Sweden. Ann-Sofie.Wernersson@miljo.gu.se
authors.forename: A S
authors.initials: AS
authors.lastname: Wernersson
authors.forename: G
authors.initials: G
authors.lastname: Dave
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D003621:Daphnia / Q000187:drug effects*; D004032:Diet; D005449:Fluorenes / Q000737:chemistry / Q000528:radiation effects / Q000633:toxicity*; D016166:Free Radical Scavengers / Q000494:pharmacology; D010777:Photochemistry; D017319:Photosensitizing Agents / Q000633:toxicity*; D012044:Regression Analysis; D012256:Riboflavin / Q000494:pharmacology; D013473:Sunscreening Agents / Q000494:pharmacology; D013997:Time Factors; D014466:Ultraviolet Rays; D014810:Vitamin E / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D005449:Fluorenes; D016166:Free Radical Scavengers; D017319:Photosensitizing Agents; D013473:Sunscreening Agents; D014810:Vitamin E; C007738:fluoranthene; D012256:Riboflavin