The risk index Lost Life Expectancy Rate (LLER) provides a unitless number (time of life expectancy lost per time exposed) describing the risk from exposure to a given hazard or from partaking in a given activity.

Simple equations to calculate the LLER from radiation-induced cancers caused by an exposure to low-level radiation were derived using the relative risk models developed by the Nuclear Regulatory Commission (upper bound estimate), the United Nations Scientific Committee on the Effects of Atomic Radiation-1988, and the National Academy of Science's Committee on the Biological Effects of Ionizing Radiation (BEIR V).

Estimates of the LLER to an average person from a continuous exposure to 0.1 muSv h-1 based on these models, respectively, are 5.5 x 10-4,9.5 x 10-4, and 9.4 x 10-4.

These values compare to LLERs of 0.015 from occupational accidents, 0.25 from being an automobile passenger, and 2.0 from cigarette smoking.

Factors effecting LLER from radiation exposures examined in this work include dose rate, age, sex, race and smoking status.