Measuring the toxicity of alkyl‐phenanthrenes to early life stages of medaka (Oryzias latipes) using partition‐controlled delivery

Abstract

Alkyl-phenanthrenes are a class of compounds present in crude oil and toxic to developing fish. Most research on alkyl-phenanthrenes has focused on retene (7-isopropyl-1-methyl-phenanthrene), but little is known about the chronic toxicity of related congeners to the early life stages of fish. This project is the first to describe the chronic toxicity of a series of alkyl-phenanthrenes to the embryos of Japanese medaka (Oryzias latipes) using the partition-controlled delivery (PCD) method of exposure and is the first to establish a relationship between toxicity of alkyl-phenanthrenes and log P. With PCD, test concentrations were maintained by equilibrium partitioning of test chemicals from polydimethylsiloxane (PDMS) films containing various concentrations of C1 to C4 phenanthrenes. Log film:solution partition constants (log K(fs)) and aqueous solubility limits were determined for each alkyl-phenanthrene. The prevalence of abnormalities in fish embryos increased in an exposure-dependent manner, with median effective concentration (EC50) values lower than experimental solubility limits of the compounds, and typical of environmental concentrations. Alkyl-phenanthrenes were more toxic to medaka embryos than unsubstituted phenanthrene, with effects resembling those of dioxin and indicating a specific receptor-based mechanism of toxicity. These results extend conclusions for the Exxon Valdez oil spill, suggest a specific mechanism of toxicity for alkyl-phenanthrenes, and provide a model for assessing the risks of mixture toxicity.

Diluted bitumen causes deformities and molecular responses indicative of oxidative stress in Japanese medaka embryos

“…Levels of mRNA were standardized to the housekeeping gene ribosomal protein L8 (rpl8) and relative to the respective water control treatments. pericardial edemas, the presence of a tube heart, and absence of a swim bladder, signs typical of medaka exposed to alkyl phenanthrenes (Turcotte et al, 2011). Though present in positive control fish, craniofacial deformities were also common in CEWAF exposure, but absent in WAF-treated fish.…”

“…The malformations evident as BSD in embryonic and juvenile fish exposed to oil have been attributed largely to the toxic effects of 3-to 5-ringed PAH, including alkyl-phenanthrenes (Adams et al, 2014b;Incardona et al, 2006Incardona et al, , 2011aFallahtafti et al, 2012;Turcotte et al, 2011), although the myriad of compounds comprising dilbit may include unknown constituents that contributed to embryotoxicity. Here, we present the first report of similar malformations in Japanese medaka hatchlings exposed to dilbit.…”

“…Toxicity testing followed the methods outlined by Turcotte et al (2011) andFallahtafti et al (2012). Each replicate contained duplicate jars of 10 embryos per treatment (n = 40 per treatment).…”

The effect of the water soluble fraction of crude oil on survival, physiology and behaviour of Caspian roach, Rutilus caspicus (Yakovlev, 1870)

“…The gel method has been successfully used in toxicity tests on epibenthic invertebrate animals (Patrick Gauthier, personal communication) and fish larval stages (Turcotte et al, 2011) in small exposure volumes, but the reliability of this method needs to be tested on larger animals in larger exposure volumes. Additionally, this method has been used for delivering hydrocarbons from laboratory made, highly concentrated stocks and needs some justifications before it can be used for naturally low concentrated stocks such as WSF.…”

History of environmental contamination by oil sands extraction

“…In one lake [NE20 (1)], concentrations of seven PAHs exceeded Canadian Interim Sediment Quality Guidelines (9) but not probable effect levels. The guidelines limit pyrogenic unsubstituted PAHs, not petrogenic PAHs, which are dominated by alkyl derivatives (10) that are as much as 10 times more toxic than unsubstituted congeners [e.g., 7-isopropyl-1-methyl phenanthrene vs. phenanthrene (11)]. Given the 23-fold increase in sediment PAH concentrations over the past 50 y, and the projected 150% increase in oil sands production over the next 15 y, there is reason for concern.…”