The Toxicity of Hydroxylated Alkyl-Phenanthrenes to Embryonic Fish
PAH , Metabolism
Polycyclic aromatic hydrocarbons (PAH) are common aquatic contaminants found at industrially contaminated sites. Alkylated PAH have been identified as a component of oil that is chronically toxic to the early life stages of fish. These compounds are important target analytes in Natural Resource Damage Assessment following oil spills, and often the focus of remedial activities. However, the mechanisms of PAH and alkyl-PAH toxicity are not well understood. The enzymatic metabolism of alkyl-PAH generates ring (OH-ring) and chain hydroxylated (OH-chain) derivatives, and has been associated with the increased prevalence of toxicity in early life stages (ELS) of fish. The role of PAH metabolism in toxicity remains unclear, and may involve the byproducts of metabolism such as reactive oxygen species (ROS), reactive intermediates, metabolites themselves, or a combination thereof. Using 1-methylphenanthrene (1MP) as a model alkyl-PAH, this research describes the relative toxicity of a suite of hydroxylated alkyl-PAH to the early life stages of fish, proposing an association between the formation of para-quinones and enhanced toxicity. The results of this thesis demonstrate: (1) hydroxylated derivatives of 1MP differ in toxicity from their non-hydroxylated counterpart; (2) ring hydroxylated 1MP derivatives are more toxic than both chain-hydroxylated derivatives and 1MP itself; (3) the location of ring-hydroxylation can affect toxicity and (4) the octanol-water partition coefficient (Kow) is a poor predictor of toxicity for hydroxylated APs derivatives.