Alternatives to radioactivity

There is an increasing trend to replace radioactive detection methods by approaches which exploit spectrophotometry, particularly UV/VIS absorption, fluorescence and chemiluminescence (Levy and Herrington 1995 Howard 1993). So, for example, radioimmunoassays (RIA) have been effectively replaced by enzyme-linked immunosorbent assays (ELISA) (Sect. 6.2.4) in which the enzyme-catalysed liberation of a 

Barker, K. (Ed.) (1998) At the Bench A Laboratory Navigator. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY. 

Beynon, R.J., Easterby, J.S. (1996) Buffer Solutions The Basics. BIOS Scientific Publishers, Oxford. 

Chambers, J.A.A. (1993) Buffers, chelating agents and denaturants, in Biochemistry Lahfax (J.A.A. Chambers, D. Rickwood, Eds.). BIOS Scientific Publishers, Oxford. 

(1997) The Laboratory Companion A Practical Guide to Materials, Equipment and Technique. Wiley-Interscience, New York, NY. 

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Isotope Methods. The isotopes of calcium have relatively short half-lives and are readily counted using liquid scintillation or gamma counters as appropriate to the nuclide. Calcium isotopes may be quantitated in the excreta, blood, tissues or in the whole body. This has made them useful for many nutritional metabolic studies. However, because of safety concerns, radioactive isotopes are cumbersome to work with and many researchers are unwilling to administer them to human beings. This has limited the use of isotopes to those studies in which alternate methods are not available or are imprecise. Methodologies for stable isotopes of calcium, which may be safely used in human being, are becoming available for use in metabolism studies. These will be practical alternatives to radioactive isotopes in the future. 

Browne TR, Szabo GK, Ajami A, Wagner D (1993). Performance of human mass balance/metabolite identification studies using stable isotope (13C, 15N) labeling and continuous-flow isotope-ratio mass spectrometry as an alternative to radioactive labeling methods. J Clin Pharmacol 33 246-252... 

A review of the synthesis and chemistry of nitroxide spin labels includes a number of steroid derivatives. Novel spin-labelled steroids have been prepared by esterification with the nitroxyl carboxylic acid derivative (17),for use in spin immunoassays (SIA) as an alternative to radioactive labelling. The prednisolone ester (18), for example, exhibits an e.s.r. spectrum with narrow lines when it is in a free state in solution, but when bound to antibody the rate of tumbling is reduced, and linewidths are broad. Signals from bound and unbound derivatives are easily distinguished and measured, so SIA of antibody-bound prednisolone provides a potentially useful serum assay method. 

In the early stages of immunoassay technology, radiolabels were employed as tracers. Isotopic labels were popular due to their high sensitivity, selectivity, and unobtrusive nature. The use of radioactive labels does have drawbacks, such as health and safety issues, short shelf life, cost, long exposure times, and disposal problems. Due to these drawbacks, there has been considerable growth in the development of nonisotopic labels for use in immunoassays. Consequently, radioactive labels are now rarely used in immunoassays. Several criteria needed to be met in order for nonisotopic labels to become a viable alternative to radioactive labels 1. Nonisoto-... 

Probes prepared with either digoxigenin- or biotin-modified nucleotides can be hybridized to Southern blots to detect target nucleic acid sequences. These methods offer an attractive alternative to radioactively tagged probes in terms of safety, cost, and efficiency. Most previous nonradioactive strategies utilized the detection of the modified base by the use of a coupled antibody- or avidin-alkaline phosphatase. The blot with the bound alkaline phosphatase was then treated with a compound, such as Nitro Blue Tetrazolium (NBT), that was converted to an insoluble, colored compound at the site of hybridization, thus facilitating visualization of the hybridized probe. 

The first alternative to radioactive labeling was addressed using enzymes as labels. Although enzymes are no signal-generating compounds, they can produce many signal-generating species. The three more... 

Labelled Cobalamin or Labelled Binding Protein. The first protein binding assays for cobalamin employed radiolabelled cobalamin and measured the amount of radioactive cobalamin bound when this label was added alone or in combination with calibrators or the sample to be tested (Rothenberg 1961). The amount of bound label decreased as the concentration of cobalamin in the cahbrator or sample increased. As an alternative to radioactive labels, the commercial companies have developed derivatives of cobalamin still able to bind to the binding protein but at the same time coupled to a property such as fluorescence (Abbott 2007 Bayer Diagnostics 2008). Another approach is to in-solubilize cobalamin and measure the amount of labelled binding protein not trapped on the in-solubilized cobalamin (Roche, 2008). 

The geologic aspects of waste disposal (24—26), proceedings of an annual conference on high level waste management (27), and one from an annual conference on all types of radioactive waste (28) are available. An alternative to burial is to store the spent fuel against a long-term future energy demand. Uranium and plutonium contained in the fuel would be readily extracted as needed. 

In 1987, CL started to be applied in DNA hybridization assays as an alternative to the use of radioactive tags. These assays are based on the specificity of a binding process that of DNA strands for each other. An unknown DNA can be identified with the Southern blot method in which the strands of the analyte are separated and allowed to interact with labeled probe DNA strands on nitrocellulose filter paper. If the label on the probe is detected, the DNA can be identified and, in some cases, quantitated. Conventionally, radioactive tags were used be-... 

Hansen, W. J., Orth, K. D., and Robinson, R. K., 1998, Cost Effectiveness and Incremental Cost Analyses Alternative to Benefit-Cost Analysis for Environmental Projects Practice Periodical of Hazardous, Toxic and Radioactive Waste Management, January, pp. 8-12. 

Ahmed, S.A., Gogal, R.M. Jr, and Walsh, J.E., A new rapid and simple non-radioactive assay to monitor and determine the proliferation of lymphocytes an alternative to (3H)thymidine incorporation assay, /. Immunol. Methods, 170, 211-224, 1994. 

Perhaps even more to the point is that the principal alternative to nuclear power is coal burning, which causes hundreds oftimes as many deaths owing to its air pollution alone in generating the same amount of electricity.11 Every time a coal-burning plant is built instead of a nuclear plant, about one thousan d extra innocent people are condemned to an early death, and this estimate applies even if the nuclear risks are those proposed by the antinuclear UCS. All the calculations leading to the above conclusions were published in prestigious scientific journals and never criticized in other published scientific papers (or elsewhere as far as I know). But none of this material was ever transmitted to the public by the mass media. Likewise it was never explained to the public that radiation doses from nuclear power are very much smaller than doses from natural radioactivity to which everyone is exposed (and which varies substantially with geography), and very much smaller than doses from medical X rays. 

The use of inorganic ion exchangers to solidify liquid radioactive waste followed by pressure sintering to produce a ceramic waste form appears to be a viable alternative to calcina-tion/vitrification processes. Both the process and waste form are relatively insensitive to changes in the composition of the waste feed. The stability of the ceramic waste form has been shown to be superior to vitrified wastes in leaching studies at elevated temperatures. Further studies on the effects of radiation and associated transmutation and the influence of temperature regimes associated with potential geologic repositories are needed for a more definitive comparison of crystalline and amorphous waste forms. 

Before going on to these alternative procedures, however, we should consider a special way by which true (not pseudo) first-order reactions are often considered. In these cases,/ = k. This consideration is especially applicable to radioactive decay processes. It is common practice to describe these true first-order reactions in terms of the time required for one-half of the material to decompose (this time is called the half-life, t ). In this special circumstance [A] = i[A]0 when t = t , and Equation 15-9 becomes... 

Requirements for Disposal. The Low-Level Radioactive Waste Policy Act of 1980 (LLRWPA, 1980), as amended by the Policy Amendments Act (LLRWPAA, 1986), governs disposal of commercial low-level waste. A particular disposal technology is not specified, but shallow-land burial was presumed in accordance with contemporary practices. The original Act (LLRWPA, 1980) directed NRC to identify alternatives to shallow-land burial for commercial low-level waste and to establish technical guidance and requirements for licensing of alternative disposal methods. NRC published technical studies of alternative disposal technologies (Bennett, 1985 Bennett and Warriner, 1985 Bennett et al., 1984 Miller and Bennett, 1985 Warriner and Bennett, 1985), but specific licensing criteria for these alternatives have not been established. 

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