Once the requisite nexus with the waste site was established, each class was strictly liable unless they could prove under section 107(b) that the release or threat of release of hazardous substances was caused solely by unrelated persons or events.

• 一旦与废物处置场确立了某种必然联系，各类人都必须负有严格的法律责任，除非他们按照第107条（b）能够证明，危险物质的泄漏和泄漏的威胁完全是无关的人和事引起的。