In recent decades, corporate and special interests have developed a wide repertoire of methods to manufacture doubt about science that threatens their interests. In the case presented here, a trade association issued a rich assortment of rhetorical claims intended to sow public confusion about university studies that threatened to undermine its industry's activities. Journalists' use of these claims appeared to vary largely as a function of their perceptions of their journalistic roles and of their audiences, though their knowledge of science also appeared to play a role. Our findings offer insight into how and why reporters respond to rhetorical claims about scientific ignorance and uncertainty that actors use to discredit threatening science. In so doing, they contribute to growing scholarship on journalists' contributions to the social construction of ignorance in scientific controversies.