Acute, flow‐through, spiked‐exposure toxicity tests were performed on the early life stages of two marine species using two oil dispersants. The species represent two common near‐shore marine taxa: molluscs (red abalone, Haliotis rufescens) and crustaceans (kelp forest mysid, Holmes‐imysis costata). The dispersants were composed of complex mixtures of anionic and nonionic surfactants and solvents. The toxicity data showed that one dispersant, Slik‐A‐Way, was more toxic than the other, Nokomis® 3, to both species. Median‐effect concentration estimates for the two dispersants were significantly different between species. Slik‐A‐Way median‐effect concentrations ranged from 16.8 to 23.9 initial ppm for Haliotis and 25.9 to 34.6 initial ppm for Holmesimysis, whereas Nokomis 3 median‐effect concentrations ranged from 21.0 to 24.0 initial ppm for Haliotis and from 118.0 to 123.2 initial ppm for Holmesimysis. Differences in toxicity seen in the two dispersants may be due to differences in surfactant formulations.
The toxicokinetics and biotransformation of pentachlorophenol (PCP) were determined in the topsmelt (Atherinops affinis). In a static system, topsmelt (n = 9) were exposed to 50 micrograms/L of [U-14C]PCP for 24 hours to determine the absorption rate constant (Ka), the whole-body bioconcentration (at steady-state conditions), the elimination rate constant (Ke), and the elimination half-life (t1/2). Kinetics were determined by direct quantitation of radioactivity in the exposure water. Following exposure, fish were placed in a flow-through metabolism chamber for 24 hours to allow depuration of retained residues, which were collected on XAD-4 resin. Excreted residues were identified and quantified by high-pressure liquid co-chromatography, fraction collection, and liquid scintillation counting. The Ka and Ke, calculated using a simplified model, were 0.012 +/- 0.005/h and 0.014 +/- 0.003/h, respectively, while the 24 hour total concentration factor was 278.0 +/- 182.0 and the t1/2 was 52.7 +/- 11.2. During 24 hours of exposure to clean seawater, topsmelt depurated 32.9% of retained residues, and while PCP was primarily excreted unchanged (64.9%), significant amounts of both pentachlorophenylsulfate (18.9%) and pentachloro-beta-D-glucuronide (16.2%) were also formed.
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