Cardiovascular effects of fission neutron or 60 Co γ exposure in the B6CF 1 mouse.

In this study, the B6CF1 mice from the JANUS program at the Argonne National Laboratory were analyzed for increased cardiovascular disease (CVD) mortality from60 Co γ ray or fission neutron exposures administered in either a single dose or protracted weekly doses. The data used for this study represent the last studies conducted at Argonne and have been archived for at least 15 years. CVD mortality increased in a dose-dependent manner from γ rays as well as from neutron exposures. The relative biological effectiveness (RBE) for neutrons is about 4 or 5. CVD mortality appeared to be enhanced when the dose was protracted, with a DDREF (dose and dose rate effectiveness factor) in the range of 0.4-0.45 for neutron and gamma ray exposure, respectively.