The Exxon Valdez oil spill occurred more than two decades ago, and the Prince William Sound ecosystem has essentially recovered. Nevertheless, discussion continues on whether or not localized effects persist on sea otters (Enhydra lutris) at northern Knight Island (NKI) and, if so, what are the associated attributable risks. A recent study estimated new rates of sea otter encounters with subsurface oil residues (SSOR) from the oil spill. We previously demonstrated that a potential pathway existed for exposures to polycyclic aromatic hydrocarbons (PAHs) and conducted a quantitative ecological risk assessment using an individual-based model that simulated this and other plausible exposure pathways. Here we quantitatively update the potential for this exposure pathway to constitute an ongoing risk to sea otters using the new estimates of SSOR encounters. Our conservative model predicted that the assimilated doses of PAHs to the 1-in-1000th most-exposed sea otters would remain 1–2 orders of magnitude below the chronic effects thresholds. We re-examine the baseline estimates, post-spill surveys, recovery status, and attributable risks for this subpopulation. We conclude that the new estimated frequencies of encountering SSOR do not constitute a plausible risk for sea otters at NKI and these sea otters have fully recovered from the oil spill.

在埃克森公司瓦尔迪兹漏油事件发生超过二十年前，和威廉王子湾生态系统基本上已经恢复。尽管如此，关于局部影响是否持续存在于海獭身上的讨论仍在继续（Enhydra lutris) 在奈特岛 (NKI) 北部，如果是，那么相关的可归因风险是什么。最近的一项研究估计了海獭与石油泄漏产生的地下残油 (SSOR) 相遇的新比率。我们之前已经证明存在暴露于多环芳烃 (PAH) 的潜在途径，并使用基于个体的模型进行了定量生态风险评估，该模型模拟了这种和其他可能的暴露途径。在这里，我们使用 SSOR 遭遇的新估计，定量更新了这种暴露途径对海獭构成持续风险的可能性。我们的保守模型预测，暴露于 1000 分之一的海獭的多环芳烃同化剂量将比慢性影响阈值低 1-2 个数量级。我们重新检查基线估计，该亚群的泄漏后调查、恢复状态和归因风险。我们得出的结论是，新估计的遇到 SSOR 的频率不会对 NKI 的海獭构成合理的风险，并且这些海獭已从石油泄漏中完全恢复。