偶尔也在这边发贴：贫铀弹的相关问题
无害的观点，来自WHO
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Executive summary
This scientific review on depleted uranium is part of the World Health Organization’s (WHO’s) ongoing process of assessment of possible health effects of exposure to chemical, physical and biological agents. Concerns about possible health consequences to populations residing in conflict areas where depleted uranium munitions were used have raised many important environmental health questions that are addressed in this monograph. Health effects Potentially depleted uranium has both chemical and radiological toxicity with the two important target organs being the kidneys and the lungs. Health consequences are determined by the physical and chemical nature of the depleted uranium to which an individual is exposed, and to the level and duration of exposure. Long-term studies of workers exposed to uranium have reported some impairment of kidney function depending on the level of exposure. However, there is also some evidence that this impairment may be transient and that kidney function returns to normal once the source of excessive uranium exposure has been removed. Insoluble inhaled uranium particles, 1-10 祄 in size, tend to be retained in the lung and may lead to irradiation damage of the lung and even lung cancer if a high enough radiation dose results over a prolonged period. Direct contact of depleted uranium metal with the skin, even for several weeks, is unlikely to produce radiation-induced erythema (superficial inflammation of the skin) or other short term effects. Follow-up studies of veterans with embedded fragments in the tissue have shown detectable levels of depleted uranium in the urine, but without apparent health consequences. The radiation dose to military personnel within an armoured vehicle is very unlikely to exceed the average annual external dose from natural background radiation from all sources. Guidance on chemical toxicity and radiological dose The monograph gives for the different types of exposure the tolerable intake, an estimate of the intake of a substance that can occur over a lifetime without appreciable health risk. These tolerable intakes are applicable to long term exposure. Single and short term exposures to higher levels may be tolerated without adverse effects but quantitative information is not available to assess how much the long term tolerable intake values may be temporarily exceeded without risk. The general public抯 ingestion of soluble uranium compounds should not exceed the tolerable intake of 0.5 礸 per kg of body weight per day. Insoluble uranium compounds are markedly less toxic to the kidneys, and a tolerable intake of 5 礸 per kg of body weight per day is applicable. Inhalation of soluble or insoluble depleted uranium compounds by the public should not exceed 1 礸/m3 in the respirable fraction. This limit is derived from renal toxicity for soluble uranium compounds, and from radiation exposure for insoluble uranium compounds. Excessive worker exposure to depleted uranium via ingestion is unlikely in workplaces where occupational health measures are in place. Occupational exposure to soluble and insoluble uranium compounds, as an 8-hour time weighted average should not exceed 0.05 mg/m3. This limit is also based both on chemical effects and radiation exposure
Radiation dose limits Radiation dose limits are prescribed for exposures above natural background levels. For occupational exposure, the effective dose should not exceed 20 millisieverts (mSv) per year averaged over five consecutive years, or an effective dose of 50 mSv in any single year. The equivalent dose to the extremities (hands and feet) or the skin should not exceed 500 mSv in a year. For exposure of the general public the effective dose should not exceed 1 mSv in a year; in special circumstances, the effective dose can be limited to 5 mSv in a single year provided that the average dose over five consecutive years does not exceed 1 mSv per year. The equivalent dose to the skin should not exceed 50 mSv in a year. Assessment of intake and treatment For the general population it is unlikely that the exposure to depleted uranium will significantly exceed the normal background uranium levels. When there is a good reason to believe that an exceptional exposure has taken place, the best way to verify this is to measure uranium in the urine. The intake of depleted uranium can be determined from the amounts excreted daily in urine. depleted uranium levels are determined using sensitive mass spectrometric techniques; in such circumstances it should be possible to assess doses at the mSv level. Faecal monitoring can give useful information on intake if samples are collected soon after exposure. External radiation monitoring of the chest is of limited application because it requires the use of specialist facilities, and measurements need to be made soon after exposure for the purpose of dose assessment. Even under optimal conditions the minimum doses that can be assessed are in the tens of mSv. There is no suitable treatment for highly exposed individuals that can be used to appreciably reduce the systemic content of depleted uranium when the time between exposure and treatment exceeds a few hours. Patients should be treated based on the symptoms observed. Conclusions: Environment Only military use of depleted uranium is likely to have any significant impact on environmental levels. Measurements of depleted uranium at sites where depleted uranium munitions were used indicate only localized (within a few tens of metres of the impact site) contamination at the ground surface. However, in some instances the levels of contamination in food and ground water could rise after some years and should be monitored and appropriate measures taken where there is a reasonable possibility of significant quantities of depleted uranium entering the food chain. The WHO guidelines for drinking-water quality, 2 礸 of uranium per litre, would apply to depleted uranium. Where possible clean-up operations in conflict impact zones should be undertaken where there are substantial numbers of radioactive particles remaining and depleted uranium contamination levels are deemed unacceptable by qualified experts. Areas with very high concentrations of depleted uranium may need to be cordoned off until they are cleaned up Since depleted uranium is a mildly radioactive metal, restrictions are needed on the disposal of depleted uranium. There is the possibility that depleted uranium scrap metal could be added to other scrap metals for use in refabricated products. Disposal should conform to appropriate recommendations for use of radioactive materials. Conclusions: Exposed populations Limitation on human intake of soluble depleted uranium compounds should be based on a tolerable intake value of 0.5 礸 per kg of body weight per day, and that the intake of insoluble depleted uranium compounds should be based on both chemical effects and the radiation dose limits prescribed in the International Basic Safety Standards (BSS) on radiation protection. Exposure to depleted uranium should be controlled to the levels recommended for protection against radiological and chemical toxicity outlined in the monograph for both soluble and insoluble depleted uranium compounds. General screening or monitoring for possible depleted uranium-related health effects in populations living in conflict areas where depleted uranium has been used is not necessary. Individuals who believe they have been exposed to excessive amounts of depleted uranium should consult their medical practitioner for examination, appropriate treatment of any symptoms and follow-up. Young children could receive greater depleted uranium exposure when playing within a conflict zone because of hand-to-mouth activity that could result in high depleted uranium ingestion from contaminated soil. This type of exposure needs to be monitored and necessary preventative measures taken. Conclusions: Research Gaps in knowledge exist and further research is recommended in key areas that would allow better health risk assessments to be made. In particular, studies are needed to clarify our understanding of the extent, reversibility and possible existence of thresholds for kidney damage in people exposed to depleted uranium. Important information could come from studies of populations exposed to naturally elevated concentrations of uranium in drinking water. | 
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