Quantitative structure–activity relationships for chronic toxicity of alkyl-chrysenes and alkyl-benz[a]anthracenes to Japanese medaka embryos (Oryzias latipes)

• Published in: Aquatic toxicology Vol. 159; pp. 109 - 118
• Main Authors: Lin, Hongkang, Morandi, Garrett D., Brown, R. Stephen, Snieckus, Victor, Rantanen, Toni, Jørgensen, Kåre B., Hodson, Peter V.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.02.2015
• Subjects: Alkylated polycyclic aromatic hydrocarbons; Alkylation; Animals; Anthracenes - chemistry; Anthracenes - toxicity; Chronic embryo toxicity; Chrysenes - chemistry; Chrysenes - toxicity; Embryo, Nonmammalian - drug effects; Medaka; Oryzias - physiology; Oryzias latipes; Partition controlled delivery; Petroleum; Polycyclic Aromatic Hydrocarbons - toxicity; Quantitative Structure-Activity Relationship; Structure-Activity Relationship; Structure–activity relationships; Water Pollutants, Chemical - chemistry; Water Pollutants, Chemical - toxicity; Medaka; Alkylated polycyclic aromatic hydrocarbons; Partition controlled delivery; Chronic embryo toxicity; Structure–activity relationships
• ISSN: 0166-445X; 1879-1514
• DOI: 10.1016/j.aquatox.2014.11.027

•Medaka embryos were exposed to alkyl chrysenes and benzo[a]anthracenes (BAA).•Concentrations were kept constant by partition controlled delivery.•Chrysene was not toxic within solubility limits, in contrast to BAA.•Alkylation increased the toxicity of chrysene and BAA.•Toxicity was related to hydrophobicity and to specific modes of action. Alkylated polycyclic aromatic hydrocarbons (alkyl-PAHs) are a class of compounds found at significant concentrations in crude oils, and likely the main constituents responsible for the chronic toxicity of oil to fish. Alkyl substituents at different locations on the aromatic rings change the size and shape of PAH molecules, which results in different interactions with tissue receptors and different severities of toxicity. The present study is the first to report the toxicity of several alkylated derivatives of chrysene and benz[a]anthracene to the embryos of Japanese medaka (Oryzias latipes) using the partition controlled delivery (PCD) method of exposure. The PCD method maintained the desired exposure concentrations by equilibrium partitioning of hydrophobic test compounds from polydimethylsiloxane (PDMS) films. Test concentrations declined by only 13% over a period of 17 days. Based on the prevalence of signs of blue sac disease (BSD), as expressed by median effective concentrations (EC50s), benz[a]anthracene (B[a]A) was more toxic than chrysene. Alkylation generally increased toxicity, except at position 2 of B[a]A. Alkyl-PAHs substituted in the middle region had a lower EC50 than those substituted at the distal region. Except for B[a]A and 7-methylbenz[a]anthracene (7-MB), estimated EC50 values were higher than their solubility limits, which resulted in limited toxicity within the range of test concentrations. The regression between log EC50s and logKow values provided a rough estimation of structure–activity relationships for alkyl-PAHs, but Kow alone did not provide a complete explanation of the chronic toxicity of alkyl PAHs.