An examination of the way in which the Environmental Protection Agency, Occupational Safety and Health Administration, and Consumer Product Safety Commission each responded to evidence of formaldehyde's carcinogenicity in animal systems reveals the interplay between politics and science policy in regulatory determinations. In some cases there were significant and unjustified departures from reasoned decision-making. Agency decisions not to take action deserve special attention by citizens, the Congress, and the judiciary to ensure that federal regulatory agencies take the necessary steps to protect the public from significant health, safety, and environmental risks.