The tobacco industry has attacked “junk science” to discredit the evidence that secondhand smoke—among other environmental toxins—causes disease. Philip Morris used public relations firms and lawyers to develop a “sound science” program in the United States and Europe that involved recruiting other industries and issues to obscure the tobacco industry's role. The European “sound science” plans included a version of “good epidemiological practices” that would make it impossible to conclude that secondhand smoke—and thus other environmental toxins—caused diseases., Public health professionals need to be aware that the “sound science” movement is not an indigenous effort from within the profession to improve the quality of scientific discourse, but reflects sophisticated public relations campaigns controlled by industry executives and lawyers whose aim is to manipulate the standards of scientific proof to serve the corporate interests of their clients.