Development of Generic Irradiation Doses for Quarantine Treatments

The impact of the CRP was to double the number of international standardised phytosanitary irradiation treatments for specific pests. Many more proposals for specific treatments were also proposed as international standards and are being examined for adoption, these include nine generic treatments proposed as a direct result of collaboration within this CRP. These International Standards for Phytosanitary Measures of the International Plant Protection Convention are used as the basis for bilateral trade agreements. Therefore, the CRP played a role is promoting the more widespread adoption of phytosanitary irradiation on a commercial scale. Up until 2004 the commercial application of irradiation was only widely used in Hawaii and Florida for inter-state trade, in order to ship fresh produce from Hawaii to other locations within the USA. International trade between nations began with Australia, which was the first country to use PI for this purpose, exporting irradiated mango to New Zealand beginning in late 2004. In subsequent years facilities in other countries began to irradiate fresh produce for international trade and by 2012 Mexico became the largest exporter of irradiated fruit. At the close of the CRP, commercial scale phytosanitary irradiation was taking place at fifteen facilities in seven countries; at five dedicated irradiation facilities and 10 multipurpose irradiation facilities. Two gamma facilities of a new design recently started operation in Hawaii and Mississippi. From Queensland, Australia now ships mangoes to other states within Australia, to New Zealand and to Malaysia. New Zealand also receives irradiated produce such as tomatoes and capsicum from Australia.

Since 1981, the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture has supported research, education and cooperation in the use of ionising radiation as a phytosanitary treatment. In this regard, the Food and Environmental Protection Sub-programme has implemented four coordinated research projects in the area of phytosanitary irradiation . These projects established the basis for developing national and international standards on the use of irradiation as a phytosanitary treatment. Specifically, in 2003 the International Plant Protection Convention (IPPC) approved the International Standard for Phytosanitary Measure (ISPM), Guidelines for the Use of Irradiation as a Phytosanitary Measure (ISPM 18), and subsequently established irradiation treatments under the IPPC Standard on Phytosanitary Treatments for Regulated Pests (ISPM 28). At the start of this CRP in 2009, eight PI treatments were adopted as annexes to ISPM 28, at the close of the CRP in 2014 there were sixteen treatments included in the annexes to the standard ISPM No. 28 Phytosanitary Treatments for Regulated Pests. The impact of the CRP was to double the number of international standardised phytosanitary irradiation treatments for specific pests. Many more proposals for specific treatments were also proposed for consideration of the International Plant Protection Convention, including nine generic treatments proposed as a direct result of collaboration within this CRP.

Another interesting output was the finding that cold treatments can be successfully used in combination with irradiation treatments. Whilst further research is needed, it was found that combining cold temperature and irradiation treatments can be synergistic, lowering the required irradiation dose. Furthermore, many of the findings of this CRP have proven that lower irradiation doses than those currently accepted could be utilised in commercial treatments. For example, the generic PI dose approved by some NPPO’s of 400 Gy (for all insects except pupae and adult Lepidoptera) could be decreased to 250 - 300 Gy based on findings of the CRP. The benefits of being able to use lower treatment doses are particularly important in commercial irradiation facilities where the dose range within the product can be relatively broad. Treatments targeting a reduced minimum dose help reduce the maximum dose received by the product and therefore ensures that fruit quality is maintained by using low intensity irradiation and it can also help optimise the commercial treatment process.

This CRP also generated a great deal of supplementary data on quality effects of different forms of irradiation on traded fruits. In general, there were no significant effects on the nutritional status of irradiated fruits at doses used for phytosanitary purposes.

The international trade of produce which has been irradiated for phytosanitary purposes is growing rapidly. Volumes of irradiated consignments have more than doubled over the duration of this CRP project. Seven countries (Australia, India, Mexico, South Africa, Thailand, USA and Vietnam) have irradiation facilities that are being used for phytosanitary treatments. Within the research community, this CRP research also improved dosimetry practices and the reporting of irradiation doses used to estalish treatments. The first RCM of the CRP emphasised the importance of proper dosimetry methods and their reporting. The reports presented during the subsequent RCMs demonstrated that the participants had acquired a greater understanding of the importance of this key parameter (and the need to work with their dosimetry service to obtain such data) in terms of irradiation research and its implication for commercial use.