Dose and Dose Rate Effectiveness Factor
ORRISK completed a study for The National Institute for Occupational Safety and Health (NIOSH) to evaluate dose and dose-rate effectiveness factors (DDREFs) for low-LET radiation (photons and electrons) for use in radiogenic cancer estimation. A DDREF is used to calculate risks in individuals exposed at low doses and low dose rates of radiation, by adjusting risks predicted by models obtained from data on humans exposed at high doses and high dose rates (e.g., data on Japanese atomic-bomb survivors).
The study evaluated the scientific basis for developing DDREFs. As part of this study we analyzed epidemiological data on dose-responses for all solid cancers as a group (incidence and mortality), female breast cancer (incidence and mortality), thyroid cancer (incidence), lung cancer (incidence and mortality), skin cancers (incidence), and leukemias (incidence and mortality). We evaluated the adequacy of linear quadratic (LQ) dose-response model for all leukemias (excluding CLL) and for specific types of leukemia, and the application of LQ models to chronic as well as acute exposures.
A comprehensive review of relevant microdosimetric and radiobiological information was included, and radiation dose-responses in cells and laboratory animals that might be relevant to estimating DDREFs for cancer in humans were evaluated, including:
- Genetic and cytogenetic data
- Cancer induction in animals
- Life shortening in animals
The study proposed probability distributions of DDREF for solid cancers as unbiased representations of the current state of knowledge. While intended for use in the Interactive RadioEpidemiological Program (IREP), the proposed DDREF can be used in any cancer risk assessments that account for uncertainty.
For more information, check out the following publications produced for this project:
