The 15-year history of a study on the health effects of low-dose radiation on workers at the Hanford Atomic Plant in Washington State demonstrates different facets of political control by employers over investigations of employee working conditions. Evidence obtained through the Freedom of Information Act shows that the original study, under the guidance of Dr. Thomas Mancuso, an experienced and respected occupational health epidemiologist, wah proof to employees that their exposure levels were safe. When it turned out that the study might show an increase in cancer rates among plant employees, its control was transferred to the employer. Public reports by scientists working for the employer are at variance with independent analyses of the same data. Lessons from these events are that it may be necessary for organized labor to negotiate the conduct of occupational health investigations as part of negotiated settlements and for legal means to be developed to make health scientists accountable for actions that influence public health policies.