Cancer incidence of the Residents from the Three Mile Island Accident Area

We report cancer risk associated with low-level radiation exposure from the March 28, 1979 Three Mile Island (TMI) accident.

The Pennsylvania Department of Health (PaDoH) established the TMI cohort by enrolling and interviewing all those present the day of the accident within a 5-mile radius. A total of 11,115 adult men and 11,770 women from TMI cohort were included. Cancer incidence data was available from 1982 to 1995 through the PaDoH cancer registry. Cox regression model was used to calculate relative risk (RR) and 95% confidence interval (95% CI) to assess incidence in four cancer sites: all malignant neoplasms (AMN), bronchus, trachea, and lung (BTL), lymph and hematopoietic tissue (LHT), and female breast associated with radiation-related exposures (background, maximum gamma, and likely gamma).

Adjusted for age, background radiation and smoking, men exposed to maximum gamma 8-19 mrem had increased risk of AMN compared to those exposed to <8 mrem (RR=1.23, 95% CI=1.00-1.52). Among women, higher likely gamma exposure increased risk for AMN (RR=1.00, 1.36, 1.41, and 1.24 for 3, 3-7, 8-15, and 16+ mrem, respectively, P=0.01). Increased female breast cancer risk was associated with likely gamma exposure (RR=1.00, 1.83, 1.88, and 1.64 for 3, 3-7, 8-15, and 16+ mrem, respectively, P<0.01) adjusted for age, education and background radiation. No relationship was found between radiation exposure and cancer incidence of BTL and LHT.

Potential increased cancer risks from low-level radiation exposure within TMI cohort can not be excluded. Information on an updated period for this group would be an important goal for future research.