Systematic review of epidemiological studies of exposure to tritium

Abstract

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.

In vivo animal studies help achieve international consensus on standards and guidelines for health risk estimates for chronic exposure to low levels of tritium in drinking water

“…The regulation of tritium exposure can be improved by generating additional accurate scientific knowledge of systemic biological responses to it (such as cancer and other aging‐associated diseases). Unfortunately, human epidemiological studies examining the health effects of tritium in workers or the general public are of limited help in deriving specific risk estimates, due to their low statistical power and the lack of tritium‐specific absorbed doses to tissues (Little and Wakeford, ; ASN, ; UNSCEAR, ). Given the complexity of the interacting systemic responses, studies using in vitro methods are unlikely to be predictive of health outcomes.…”

A reanalysis of cancer mortality in Canadian nuclear workers (1956–1994) based on revised exposure and cohort data

“…(In Canada, CANDU heavy water moderated nuclear power reactors are a potential source of occupational tritium exposure for nuclear workers. No studies to date have reported tritium-specific risks for nuclear workers (Little and Wakeford, 2008)).…”

Integrating Informative Priors from Experimental Research with Bayesian Methods

“…We focus on the effect of radiation doses from intakes of tritium and from external exposure to gamma rays. Tritium is a radioisotope of hydrogen that emits beta radiation via the release of electron energy as it decays from H 3 to He 3 24 . Unlike external penetrating radiation such as gamma- and x-rays, the low-energy beta radiation emitted by tritium travels only a short distance in tissue.…”