Theoretical Estimation of Quality Factor For Tritium

Tritium (3H) is a radioactive isotope of hydrogen. A number of factors combine to create a good deal of interest in the risks arising from exposure to tritium of both workers and members of the public. Tritium is ubiquitous in environmental and biological systems and is very mobile due to its occurrence as tritiated water. In this paper we systematically review epidemiological data relating to tritium exposure with a view to assessing the risk of such exposure using those studies that are potentially informative. The usefulness of the available studies of cancer and other adverse health effects in workforces and members of the general public is often impaired by a lack of tritium-specific dose data, low doses and small numbers of cases. A number of workforce studies have been identified in which tritium-specific individual doses have been estimated, although none of them, as presently reported, enable reliable inferences to be made on risks associated with exposure to tritium. In general, the available epidemiological studies on the offspring of radiation workers or on pregnancy outcome in areas subject to releases of tritium do not contain enough detail to estimate risks from tritium exposure. Although the studies presently reported are uninformative on risks from tritium, a number of the occupationally exposed cohorts would be potentially informative, particularly if data were suitably combined.

Section: Biological Effects Of Tritiumsupporting

confidence: 84%

Systematic review of epidemiological studies of exposure to tritium

Little

Wakeford

2008

“…These measured RBE values for tritium beta irradiation are reasonably consistent with estimates based on microdosimetric considerations (e.g. Bigildeev et al 1992, Morstin et al 1993, Moiseenko et al 1997. For the purposes of assessing risk at low chronic doses, studies of carcinogenesis are the most appropriate.…”

Section: Internal Dosimetry and Tritium-the Icrp Positionsupporting

confidence: 79%

Internal dosimetry and tritium—the ICRP position

Cox

2008

“…These measured RBEs for tritium beta irradiation are reasonably consistent with estimates based on microdosimetric considerations (e.g. Bigildeev et al 1992, Morstin et al 1993, Moiseenko et al 1997. For the purposes of assessing risk at low chronic doses, studies of carcinogenesis are the most appropriate.…”

Section: Possible Changes To Icrp Assumptions For Occupational Intake...supporting

confidence: 79%

Doses and risks from tritiated water and environmental organically bound tritium

Harrison¹

2009

This short review provides an explanation of the calculation and use of the ICRP protection quantities, equivalent and effective dose, including the simplifications introduced by using radiation and tissue weighting factors. It discusses the dose coefficients (Sv Bq(-1) intake) provided by ICRP for intakes of tritiated water (HTO) and organically bound tritium (OBT) and considers uncertainties in the human and animal data on which they are based, including information on the relative biological effectiveness (RBE) of tritium beta particles compared to gamma and x-rays. The review also addresses the specific issue of dose coefficients for ingestion of OBT in Cardiff Bay fish. A distinction is drawn between the adequacy of the ICRP calculation of effective dose to a reference person for the purposes of planning and regulatory control, and the calculation of best estimates of dose and risk to individuals. ICRP will continue to use a radiation weighting factor of 1 for all low LET radiations in the calculation of effective dose, but specific RBE data should be used in risk estimates. Uncertainties in dose coefficients are small for HTO but greater for OBT. The generic consideration of OBT provided by ICRP may not be appropriate for specific organic forms such as OBT in fish.