title: Environmentally Relevant Chronic Low-Dose Tritium and Gamma Exposures do not Increase Somatic Intrachromosomal Recombination in pKZ1 Mouse Spleen.
abstract: The toxicity of tritium is a public health concern given its presence and mobility in the environment. For risk predictions using radiological protection models, it is essential to allocate an appropriate radiation weighting factor (WR). This in turn should be consistent with the observed relative biological effectiveness (RBE) of tritium beta radiation. Although the International Commission on Radiological Protection (ICRP) currently recommends a WRof 1 for the calculation of committed effective dose for X rays, gamma rays and electrons of all energies, including tritium energies, there are concerns that tritium health risks are underestimated and that current regulatory tritium drinking water standards need revision. In this study, we investigated potential cytotoxic and genotoxic effects in mouse spleen after one month and eight months of chronic exposure to low-dose tritiated water (HTO). The dose regimes studied were designed to mimic human chronic consumption of HTO at levels of 10 kBq/l, 1 MBq/l and 20 MBq/l. The total doses from these radiation exposures ranged from 0.01 to 180 mGy. We also compared the biological effects of exposure to HTO with equivalent exposure to external whole-body60Co gamma rays. Changes in spleen weight and somatic intrachromosomal recombination (DNA inversions) in spleen tissue of pKZ1Tg/+mice were monitored. Our results showed no overall changes in either spleen organ weights and no increase mouse splenic intrachromosomal recombination frequencies, indicating that current drinking water standards for tritium exposure in the form of HTO are likely to be adequately protective against cytotoxic and genotoxic damage in spleen. These results demonstrate no evidence for cytotoxicity or genotoxicity in mouse spleen following chronic exposures to HTO activities (or equivalent gamma doses) up to 20 MBq/L.
authors.affiliation: a   Canadian Nuclear Laboratories, Chalk River, Ontario, Canada.
authors.forename: Laura
authors.initials: L
authors.lastname: Bannister
authors.affiliation: a   Canadian Nuclear Laboratories, Chalk River, Ontario, Canada.
authors.forename: Mandy
authors.initials: M
authors.lastname: Serran
authors.affiliation: a   Canadian Nuclear Laboratories, Chalk River, Ontario, Canada.
authors.forename: Lindsey
authors.initials: L
authors.lastname: Bertrand
authors.affiliation: a   Canadian Nuclear Laboratories, Chalk River, Ontario, Canada.
authors.forename: Dmitry
authors.initials: D
authors.lastname: Klokov
authors.affiliation: a   Canadian Nuclear Laboratories, Chalk River, Ontario, Canada.
authors.forename: Heather
authors.initials: H
authors.lastname: Wyatt
authors.affiliation: a   Canadian Nuclear Laboratories, Chalk River, Ontario, Canada.
authors.forename: Melinda
authors.initials: M
authors.lastname: Blimkie
authors.affiliation: b   Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PRP-HOM, Fontenay-aux-Roses, France.
authors.forename: Yann
authors.initials: Y
authors.lastname: Gueguen
authors.affiliation: a   Canadian Nuclear Laboratories, Chalk River, Ontario, Canada.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Priest
authors.affiliation: b   Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PRP-HOM, Fontenay-aux-Roses, France.
authors.forename: Jean-René
authors.initials: JR
authors.lastname: Jourdain
authors.affiliation: c   Flinders Centre for Innovation in Cancer, Flinders University of South Australia, SA, Australia.
authors.forename: Pamela
authors.initials: P
authors.lastname: Sykes
mesh_terms: D000818:Animals; D033481:Chromosomes, Mammalian / Q000235:genetics* / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D004777:Environment; D005720:Gamma Rays / Q000009:adverse effects*; D051379:Mice; D008810:Mice, Inbred C57BL; D011874:Radiometry; D011995:Recombination, Genetic / Q000528:radiation effects*; D013154:Spleen / Q000378:metabolism* / Q000528:radiation effects; D014316:Tritium / Q000009:adverse effects*
chemical_list: D014316:Tritium