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In their recent paper, Page et al. concluded that spilled oil lost toxicity due to weathering and that it dispersed from beaches so rapidly that the potential for toxicity is now, 13 years after the spill, negligible. Their conclusions, however, are based on insensitive toxicity tests, a statistical design with low power, and invalid assumptions regarding the extent and location of remaining oil.
Although Page et al. make a convincing case that the narcotic toxicity of Exxon Valdez oil declined rapidly after the spill, the claim that all oil toxicity has similarly declined requires a higher standard of evidence. They estimate sediment toxicity from mortality in 10-d amphipod bioassays; however, measures of lethal responses in adult animals are usually less sensitive than sublethal measures, particularly in early life stages. To fully assess the toxic potential of contaminated sediment, evaluation of multiple taxa is frequently recommended. The absence of acute sediment toxicity does not demonstrate the absence of benthic degradation.