On Mar. 28, 1979, the U.S. Centers for Disease Control and Prevention (CDC) investigated health effects related to the Three-Mile Island nuclear accident.

Proximity of residence to the plant, which related to distress in previous studies, was taken as a possible indicator of accident stress; the postaccident pattern in cancer rates was examined in 69 “study tracts” within a 10-mile radius of TMI, in relation to residential proximity.

A postaccident increase in cancer rates near the Three Mile Island plant was notable in 1982, persisted for another year, and then declined. Radiation emissions, as modeled mathematically, did not account for the observed increase. An alternative mechanism for the cancer increase near the plant is through changes in care-seeking and diagnostic practice arising from postaccident concern.