Radiation protective chemicals

Glass has been the container of choice for pharmaceutical dosage forms because of its resistance to decomposition by atmospheric conditions or by solid or liquid contents of different chemical compositions [1]. Furthermore, by varying the chemical composition of glass, it is possible to adjust the chemical behavior and radiation protective properties of glass. 

Since 1925, The International Commission on Radiation Units and Measurements at Bethesda, Maryland has been publishing reports updating the definitions and units for measurements of various radiation-related quantities. Of these ICRU Reports, special mention may be made of reports no. 19 (1971) [radiation quantities and units], 33 (1980) [radiation quantities and units], 36 (1983) [microdosimetry], 47 (1992) [thermoluminiscent dosimetry], and 51 (1993) [radiation protection dosimetry]. A succinct description of various devices used in dosimetry, such as ionization chambers, chemical and solid-state dosimeters, and personnel (pocket) dosimeters, will be found in Spinks and Woods (1990). In this section, we will only consider some chemical dosimeters in a little detail. For a survey of the field the reader is referred to Kase et at, (1985, 1987), McLaughlin (1982), and to the International Atomic Energy Agency (1977). Of the earlier publications, many useful information can still be gleaned from Hine and Brownell (1956), Holm and Berry (1970), and Shapiro (1972). 

The following physical, chemical, and biological factors related to the metabolism of inhaled and ingested radiocerium are recommended for establishing radiation protection guidelines ... 

PHYSICAL, CHEMICAL, AND BIOLOGICAL PROPERTIES OF RADIOCERIUM RELEVANT TO RADIATION PROTECTION GUIDELINES... 

Cerium, an element in the lanthanide series, has a number of radioactive isotopes. Several of these are produced in abundance in nuclear fission reactions associated with nuclear industry operations or detonation of nuclear devices. This report summarizes our present knowledge of the relevant physical, chemical, and biological properties of radiocerium as a basis for establishing radiation protection guidelines. 

Potassium iodine tablets can be used to reduce radioactive iodine exposure to the thyroid gland. According to the National Council of Radiation Protection and Measurement (NCRP), taking 130 milligrams of potassium iodine at or before exposure to radioactive iodine effectively blocks nearly 100% of radioactive iodine from reaching the thyroid (1977). See Table 3.3 for a summary of antidotes for various chemical and biological agents. 

Albert. R.E. (1983) The acceptability of using the cancer risk estimates associated with the radiation protection standard of 5 lems/year as the basis for setting protection standards for chemical carcinogens with special reference to vinyl chloride, Report to Ministry of Labor, Occupational Health and Safety Division, Ibronto, Ontetrio, Canada (Ministry of Labor, Occupational Health and Safety Division, Ibronto, Ontario, Canada). 

National Council on Radiation Protection and Measurem its. Comparative Carcinogenicity of Ionizing Radiation and Chemicals. 

Some of the commercial uses that pseudoureas have found are herbicides [27, 28] inhibitors for discoloration of color photographic layers [29] monomers for the preparation of some novel copolymers [30, 31] and dyes [32,33]. A survey of the recent decennial indexes of Chemical Abstracts should be made to see the large number of pseudoureas reported for varied uses. Pseudothioureas have also been found useful as radiation protective agents [34]. 

Wright HA, Magee JL, Hamm RN, Chatterjee A, Turner JE, Klots CE (1985) Calculations of physical and chemical reactions produced in irradiated water containing DNA. Radiat Protect Dosimetry 13 133-136... 

Skin constitutes the interface between the human body and the environment. It represents a major target of oxidative stress since it is exposed to external oxidant aggressions like UV radiation, ozone, chemicals or pollution. Continuous exposure to such damaging effects and/or deficiency of the antioxidant protection systems result in skin premature aging and contribute to the development of cutaneous diseases and cancers [23]. Electrochemical studies dealing with the effect... 

This Report presents recommendations of the National Council on Radiation Protection and Measurements (NCRP) on a new system for classifying waste that contains hazardous substances, either radionuclides or hazardous chemicals. NCRP s recommendations incorporate three principles. 

For the purpose of classifying waste that contains radionuclides, NCRP reaffirms use of the nominal probability coefficient for fatal cancers (i.e., the probability of a fatal cancer per unit effective dose) of 0.05 Sv 1 normally assumed in radiation protection of the public. For chemical carcinogens, NCRP believes that MLEs of probability coefficients obtained from the linearized, multi-stage model should be used in classifying waste, in order to provide reasonable consistency with the probability coefficient for radionuclides. The use of MLEs for chemical carcinogens usually will result in substantially lower probability coefficients than the use of upper 95 percent confidence limits. 

Similar considerations apply to the discussions of approaches to risk management in Section 3.3. Readers who are knowledgeable about principles of radiation protection may not be familiar with the different approach to health protection used for hazardous chemicals, and vice versa, and an understanding and resolution of the different approaches to risk management is important in developing a comprehensive and risk-based waste classification system. 

First, the threshold for hazardous chemicals that cause deterministic effects is assumed for purposes of health protection to represent a lower confidence limit, taking into account uncertainties in the dose-response relationship (see Section 3.2.1.2.7). Depending, for example, on the slope of the dose-response relationship near the threshold, the chosen steps in the dosing regimen, and the magnitude of uncertainties in the data, the lower confidence limit of the assumed threshold can be substantially below MLE. In radiation protection, the estimated thresholds for deterministic effects are based on MLEs of dose-response relationships (ICRP, 1991). 

Second, the primary measure of stochastic response used in radiation protection and in most radiation risk assessments has been fatalities. In contrast, the measure of response for chemicals causing... 

The chemical paradigm also differs from the radiation paradigm in that there are no standards that apply to all controlled sources of exposure and all hazardous substances combined, as in radiation protection standards. Regulations for hazardous chemicals generally apply only to specific release pathways (eg., the atmosphere) or... 

The primary measure of stochastic responses for radionuclides used in radiation protection has been fatalities, whereas incidence is the universal measure of stochastic responses for hazardous chemicals. 

This Section briefly reviews previous recommendations of NCRP that are potentially relevant to the development of a risk-based waste classification system. The topics discussed include NCRP s recommendations on radiation protection of the public and the comparative hazards of ionizing radiation and chemicals. 

This option does not appear to be advantageous for either radionuclides or chemicals that cause stochastic responses. In radiation protection, total detriment is used mainly to develop the tissue weighting factors in the effective dose (see Section 3.2.2.3.3), but ICRP and NCRP have continued to emphasize fatal responses as the primary health effect of concern in radiation protection and radiation risk assessments. Since total detriment is based on an assumption that fatalities are the primary health effect of concern, the same difficulties described in the previous section would occur if this measure of response were used for chemicals that induce stochastic responses. Other disadvantages of using total detriment include that detriment is not a health-effect endpoint experienced by an exposed individual and the approach to weighting nonfatal responses in relation to fatalities is somewhat arbitrary. Furthermore, total detriment is not as simple and straightforward to understand as either incidence or fatalities. 

NCRP (1989). National Council on Radiation Protection and Measurements. Comparative Carcinogenicity of Ionizing Radiation and Chemicals, NCRP Report No. 96 (National Council on Radiation Protection and Measurements, Bethesda, Maryland). 

Physical, Chemical, and Biological Properties of Radiocerium Relevant to Radiation Protection Guidelines (1978)... 

In contrast, radiation protection policy (ICRP 2008) benefits from an assumption of linearity as a tool to attribute causation in an equitable way. Linear dose-response relationships could also serve a useful purpose for chemical safety, with the following qualifications ... 

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