Review of existing Australian radionuclide activity concentration data in non-human biota inhabiting uranium mining environments

Data Collection, Review and Evaluation

1.7Data Collection

1.7.1Australian input to the Wildlife Transfer Parameter Database

The ERISS data was reported to the WTD as whole-organism CRs that they had calculated using the common approach outlined in this report. The ANSTO data were reported as a mixture of tissue and whole-organism CRs. Tissue CRs were then converted by the managers of the WTD to whole-organism CRs. It should be noted that the ANSTO data were supplied included data on sheep and these are not included in the WTD as they do not meet the WTD definition of ‘wildlife’. These data will be included in Appendix 3 of this report for comparative purposes. The ANSTO data also included Maralinga data for Cs-137, Am-241 and Pu isotopes, and these will not be discussed in this report. In addition to the data provided by ANSTO and ERISS there was a limited amount of additional Australian data that had been included in the WTD from other sources. These were also provided to ARPANSA during this review by Dr Nick Beresford of the Centre for Ecology & Hydrology (CEH), United Kingdom.

The data manipulations to calculate whole-organism CRs undertaken by ERISS, ANSTO and the managers of the WTD for all the Australian data currently in the WTD were reviewed during this project. This was to ensure that the process utilised was clearly understood and recorded for reference, to ensure consistency in approach for future data manipulations. It also provided an extra level of quality assurance for data submitted to the WTD and identified some inconsistencies and duplication of data that will need to be addressed in the future.

1.7.2Library searches

1.7.3Uranium industry

A number of mining companies advised that they held no data or limited data that would be useful for the purposes of this project. Other companies do hold data for radionuclide activity concentrations in non-human biota which had largely been collected for the purposes of human food-chain ingestion exposure assessments. During the course of the data collection phase these were not able to be adequately matched with appropriate media data to enable concentration ratios to be calculated. Additionally, there is a significant body of data that were collected during the 1970s and 1980s in preparing baseline environmental surveys and assessing mining impacts, predominantly by the Australian Atomic Energy Commission (AAEC) (now ANSTO). Some tissue CRs have already been reported in the literature from these AAEC reports (Johansen & Twining, 2010) and many of these reports contain significant amounts of flora data which have not previously been summarised and can be utilised to calculate CRs.

It is recommended that a cooperative relationship with industry is built upon to establish a robust non-human biota dataset and additional industry data is pursued. This is particularly relevant for those unpublished datasets that are known to exist but have not yet been paired with media data.

1.8Data Review and Evaluation

documentation of sample collection, preparation, and analysis methods were described and conformed to generally accepted practice

non-human biota were not constrained to laboratory enclosures or mesocosms

sampling of media (water, soil, sediment) was representative of the natural environment from which the biota was collected

the period of time of biota exposure to radionuclides was generally consistent with the equilibrium assumption

pooled samples were for the same or closely related species.

When reviewing the datasets against these criteria there were some datasets that could not be adequately matched with media and were excluded from further analysis. This does not mean media data does not exist, but further investigation may be required to adequately pair biota with a media activity concentration representative of the biota’s natural environment. A summary of the reports, publications and other unpublished data reviewed and evaluated during the course of this project is provided in Appendix 1.

1.9Data Manipulation

In these cases, to determine whole-organism CR_WO-media values from reported activity concentrations the following data manipulation process was followed:

1. 
   Data reported in pico-curies were converted to becquerels.
   
2. 
   Data reported on a dry- or ash- mass basis instead of fresh-mass basis were converted to a fresh-mass basis using conversion factors selected in the following order of priority:
   

(b) ash or dry weight to fresh weight ratios (generic) as reported in Beresford et al. (2008b) for terrestrial ecosystems, or Hosseini et al., (2008) for aquatic ecosystems (see Appendix 2)

(c) ash or dry weight to fresh weight ratios as reported in other available publications as noted.

3. 
   When data were reported for specific tissues, instead of whole-organism, a conversion was made to a whole-organism on the following priority basis:
   

(b) whole-organism:tissue concentration ratios were calculated using conversion factors from Yankovich et al. (2010), Hosseini et al. (2008) or Wood et al. (2010); If a number of tissue CRs are given for the same organism (e.g muscle, liver & kidney) then the CR_WO-media calculated for each tissue is then averaged to determine one CR_WO-media for that sample

(c) whole organism:tissue conversion factors reported in other publications as noted.

A table of the IAEA summary CR_WO-media and Australian CR_WO-media that are relevant to the uranium mining and milling industry is provided in Appendix 3. The Australian CR_WO-media included in this table have been reported to the WTD and are therefore taken into account when deriving the IAEA summary CR_WO-media values. These are provided for information and no detailed analysis or conclusions have been reached in regard to how they the Australian values compare to the IAEA summary values. It should be noted that during the course of this review it was identified that there are some corrections required to the Australian datasets currently within the WTD. These values will be modified in the future and corrections made to the WTD. This process has already been discussed with the WTD and the relevant contributors.

In addition to reviewing the existing CR_WO-media significant progress was made during the course of this project in calculating new CR_WO-media for non-human biota relevant to the uranium mining and milling habitats. The datasets assessed have enabled CR_WO-media to be calculated for uranium decay series radionuclides for a number of additional wildlife groups that had not been previously included in the WTD. This included the wildlife groups of grasses, shrubs and trees, more limited amounts of information have been identified for birds and algae. The review will also increase the amount of data for the wildlife groups of terrestrial mammals and reptiles, and freshwater reptiles, molluscs, fish and vascular plants. A summary of the wildlife groups identified during this project where whole-organism CRs can be calculated, species within those groups and their habitats is provided in Appendix 4.

Concurrent to this project ERISS has also been reviewing its database of bushfoods and media activity concentrations that can potentially be used to calculate whole-organism CRs. This process is building on the CRs that ERISS have already provided to the WTD. Additional data may be available in the future after publication by ERISS.

It is recommended that the new CR_WO-media values from this project be collated with the current WTD CRs and the additional ERISS CRs and once assembled this information should be made available through publication as an ARPANSA technical report or an alternative format. Once published this information should be incorporated into the WTD and a comparison of Australian CRs to the IAEA and ICRP summary values should then be undertaken.