§ Mr. Ashdownasked the Secretary of State for Social Services what information he has as to the typical latent periods before diagnosis of different types of cancer and leukaemia following exposure to nuclear radiation above background levels; and if he will make a statement on the consequences for reliable epidemiological studies.
§ Mr. Kenneth ClarkeLatent periods are considered to vary depending on the dose received, the age at which it is received and the organ or tissue exposed or irradiated with a mean of between 12 and 25 years. The subject is considered at greater length in the National Radiological Protection Board's report NRPB-R171 — The Risks of Leukaemia and other Cancers in Seascale from Radiation Exposure".
Such variations are taken into account when epidemiological studies are undertaken, and mean that the period of follow-up necessary before firm conclusions can be drawn on possible effects will vary according to the cancer-type under consideration.
§ Mr. Ashdownasked the Secretary of State for Social Services what reliable epidemiological data are available to him on the incidence of health effects, including cancers, caused by exposure to small amounts of nuclear radiation; and if he will publish a list of the relevant studies, stating in each case (a) the period of time covered by the data and (b) whether dose rates of radiation exposure were accurately known.
§ Mr. Kenneth ClarkeThis is an extremely complex subject. The United Nations Scientific Committee on the Effects of Atomic Radiation report regularly on this topic to the General Assembly. Their 1977 and 1982 reports* and annexes include data and references on small doses of radiation from pre-natal, occupational and nuclear fall-out exposures.
* Sources and Effects of Ionising Radiation — 1977 UNSCEAR report; Ionising Radiation: Sources and Biological Effects—1982 UNSCEAR report.
§ Mr. Ashdownasked the Secretary of State for Social Services what epidemiological studies have been undertaken to investigate the relative incidence of cancers in areas of the United Kingdom with differing levels of background nuclear radiation; and if he will make a statement.
§ Mr. Kenneth ClarkeWe are not aware of any such studies. There is, however, a study under way at present which will compare the geographical variations of medical and non-medical radiation exposures within the United Kingdom and the rates of cancer in children.