This document was prepared to provide scientific basis for recommended changes in specific limits for tritium surface contamination in DOE Order 5480.11. A summary of the physical and biological characteristics of tritium has been provided that illustrate the unique nature of this radionuclide when compared to other pure beta emitters or to beta-gamma emitting radionuclides. This document is divided into nine sections. The introduction and the purpose and scope are addressed in Section 1.0 and Section 2.0, respectively. Section 3.0 contains recommended interpretation of terms used in this document. Section 4.0 addresses recommended methods for evaluating surface contamination. Biological and physical characteristics of tritium compounds are discussed in Section 5.0, as they relate to tritium radiotoxicity. Scenarios and dose calculations for selected, conservatively limiting cases of tritium intake are given and discussed in Section 6.0 and Section 7.0. Section 8.0 provides conclusions on the information given and recommendations for changes in the surface contamination limits for total tritium to 1 x 10 dpm per 100 ? C O cm and removable tritium to 1 x 10 dpm per 100 cm'^. Section 9.0 is a listing of references. A summary of comments made on the October 1990 draft of this document as received from the members of the DOE Tritium Surface Contamination Limits Committee is contained in the Appendix with a description of the responses provided.
The equine placenta being epitheliochorial, is a barrier to immunoglobulins, which means that the foal is unable to receive passive immunity (Davies Morel, 2003) other than a small quantity of IgM which is synthesised in utero. McClure (as cited in McKinnon and Voss, 1993) suggests that the most significant component of passive immunity passed to foals, is that obtained from colostral immunoglobulins. When the foal ingests the colostrum and absorbs the antibodies therein, a temporary protection is provided until autogenous production of immunoglobulins reaches protective levels (McClure as cited in McKinnon and Voss, 1993). It is highly important that the foal receives colostrum within the first 24 hours and preferably within the first 12 hours of life (Davies Morel, 2003). This enables immunoglobulins to be absorbed by enterocyte cells lining the small intestine which are controlled by cortisol, and over time are replaced by ones which are unable to absorb proteins. For foals where colostrum is not readily available (for example, if the foal is orphaned at birth), then stored colostrum could be used. However, it is postulated that IgG integrity could be compromised by freezing, and consequently, thawing of the colostrum. The aim of this experiment is to evaluate five thawing methods for their ability to preserve IgG content of stored colostrum.
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