KETHLEDGE, Circuit Judge. Seldom is so ambitious a case filed on so slight a basis. The gravamen of Kevin Hardwick’s complaint is that his bloodstream contains trace quantities of five chemicals—which are themselves part of a family of thousands of chemicals whose usage is nearly ubiquitous in modern life. Hardwick does not know what companies manufactured the particular chemicals in his bloodstream; nor does he know, or indeed have much idea, whether those chemicals might someday make him sick; nor, as a result of those chemicals, does he have any sickness or symptoms now. Yet, of the thousands of companies that have manufactured chemicals of this general type over the past half-century, Hardwick has chosen to sue the ten defendants present here. His allegations regarding those defendants are both collective—rarely does he allege an action by a specific defendant—and conclusory. Yet Hardwick sought to represent a class comprising nearly every person “residing in the United States”—a class from which, under Civil Rule 23(c), nobody could choose to opt out. And as relief for his claims, Hardwick asked the district court to appoint a “Science Panel”—whose conclusions, he said, “shall be deemed definitive and binding on all the parties[.]”

The district court, for its part, certified a class comprising every person residing in the State of Ohio—some 11.8 million people. The defendants now appeal that order, arguing (among many other things) that Hardwick lacks standing to bring this case. We agree with that argument, and remand with instructions to dismiss the case.