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Title: Doses from the consumption of Cardiff Bay flounder containing organically-bound tritium
Author: A Hodgson
Author: J E Scott
Author: T P Fell
Author: J D Harrison
Author: Environment Agency
Document Type: Monograph
Annotation: Environment Agency Project ID:EAPRJOUT_1465, Representation ID: 510, Object ID: 2619
International Commission on Radiological Protection (ICRP) dose coefficients for the ingestion of organically bound tritium (OBT) by human adults and children are intended for general application to unspecified forms of OBT in diet and may not be applicable to intakes of a specific form of OBT. However fish caught in Cardiff Bay have had unexpectedly high levels of tritium, which has been attributed to the different chemical form of OBT, although the mechanisms of accumulation are not fully understood. This study was conducted to determine the uptake and retention of tritium in adult rats after administration as either tritiated water (HTO) or OBT found in dried flounder flesh from fish caught in Cardiff Bay to assess whether the ICRP dose coefficients are applicable to OBT in fish caught in the Bay. Two components of retention were obtained in either the HTO or OBT uptake experiment. The first component, attributable to tritium equilibrating with body water, had a half-time of retention of 3 days in each case, and accounted for 97% of the intake as tritiated water and 70% after intake of OBT in flounder. The results were consistent with the rapid breakdown of a large proportion of the flounder OBT to tritiated water. The second component of retention, attributable to OBT in rat tissues, accounted for 3% of tritium intake as tritiated water and 30% after intake as flounder OBT; the half-time of retention were 10 and 25 days respectively. The results obtained for tritiated water are consistent with published animal data and correlate with the ICRP assumptions. The results for the OBT experiment suggest that appropriate assumptions for retention in adults are 70% with a 10- day half-time and 30% with a 100-day half-time. These assumptions result in an ingestion dose coefficient of 6 x 10-11 Sv/Bq. This is slightly greater than the ICRP value for OBT ingestion by adults of 4.2 x 10-11 Sv/Bq. In conclusion, it is proposed that a revised dose coefficient of 6 x 10-11 Sv/Bq-1 should be applied to OBT in flounders caught in Cardiff Bay. It is also proposed that this dose coefficient should be applied to all ingestion intakes by adults relating to this source of exposure, unless specific information is available showing that a significant proportion of the intake is HTO. The same proposals apply to dose coefficients derived here for flounder OBT consumption by children.
Publisher: Environment Agency
Subject Keywords: TritiumEstuariesWater pollutionRadioactive pollutantsFishesBioaccumulationPublic health
Geographic Keywords: Wales
Taxonomic Keywords: Platichthys flesus
Extent: 22
Total file downloads: 289

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