Asbestos manufactures have been aware of dangers of asbestos exposure for many decades, but they chose to conceal any such information so that it would not cause concern in the workers and consumers. For instance, in the early 1980s, it came to light that Johns-Manville, one of the largest asbestos manufacturers, had been fully aware of the connection between exposure to asbestos dust and the development of serious respiratory disease for at least fifty years. During that fifty-year period, Johns-Manville not only failed to warn potential victims of the risks associated with its product, but it also actively concealed that information in order to safeguard company profits. As one particularly egregious act in a large-scale cover-up, the company routinely withheld x-ray results from periodic employee physical exams – refusing to inform their employees that many of them were suffering from serious respiratory diseases.

In a 1949 company memorandum, the medical director of Johns-Manville, stated that the employees "have not been told of the diagnosis, for it is felt that as long as the man feels well, is happy at home and at work and his physical condition remains good nothing should be said." This unconscionable practice subjected the sick employees to additional exposure to asbestos, substantially contributing to the seriousness of their illness. As a result, many employees would not discover their illness until after retirement, when the statute of limitations on their workers compensation and tort claims had already elapsed.

This practice, however, placed Johns-Manville in a win-win situation. Not only did the company benefit from the additional years of labor by experienced employees, but it also increased the likelihood that they would escape all liability for their intentional misconduct. In a further attempt to conceal the dangerous nature of their product, Johns-Manville and other manufacturers persuaded scientists to delay publication of findings that would be detrimental to the asbestos industry, or to soften the impact of such reports by obscuring their results.