The researchers studied how exposure to low levels of neutron radiation affects certain substances in the blood of rats. They exposed some rats to low-dose neutron radiation for a long time and compared them to rats that were not exposed. They found that the radiation did not significantly change the levels of superoxide dismutase or malondialdehyde in the rats' blood. This suggests that prolonged exposure to this type of radiation may not have a major impact on these substances in the body.