Health risk of low-dose ionizing radiation

6 problems

• Circulatory disease risk from radiation below 50 rad

  Contested

  High radiation doses to the heart and blood vessels raise the risk of heart attack and stroke. Whether low doses do the same, and in proportion to dose, is disputed.

• Causal cancer risk from diagnostic CT exposure

  Contested

  Children scanned by CT show slightly more cancers later, but sicker children get scanned more often, which could explain the association by itself.

• Value of the dose and dose-rate effectiveness factor

  Contested

  Risk estimates from survivors of single sudden exposures are scaled down before being applied to slow exposures. The scaling number is chosen by committee rather than measured.

• Physical markers of individual radiosensitivity

  Open

  A minority of patients suffer unusually severe side effects from standard radiotherapy doses. There is no reliable test to find them in advance.

• Does risk stay linear below 10 rad

  Contested

  Protection rules assume that halving a small dose halves the risk, with no safe threshold. Direct evidence at such doses is thin and the assumption is contested.

• In vivo relevance of bystander and non-targeted effects

  Open

  Cells that were never hit by radiation sometimes show damage because neighbours were hit. Whether this matters in a living body at low dose is unknown.