Veteran Member Join Date: Oct 2007 Location: lowell,ma |
The SCHER adopted this opinion at its 7th plenary on 18 May 2010 after public consultation
Measured concentrations of DU in environmental samples - Specific concerns have been raised regarding human and environmental exposure to DU in areas where DU ammunition has been used. A detailed assessment of such potential exposures has been performed in Kosovo (Danesi et al., 2003b; Salbu et al., 2003; UNEP, 2001), Serbia- Montenegro (McLaughlin et al., 2003), Bosnia and Herzegovina (UNEP, 2003), Kuwait (IAEA, 2003; Salbu et al., 2005) and Iraq (Gerdes et al., 2004; IAEA, 2009). Residues of DU ammunitions have also been detected in military proving grounds (Sowder et al., 1999). Concentrations of DU in areas with intensive use of DU ammunition in Kosovo varied from a few mg DU/kg soil at depths of 40 cm up to about 18,000 mg DU/kg soil close to the surface. Some small spots contained hundreds of thousands of DU particles in a few milligrams of soil. However, despite the reported huge variability in DU concentrations, in most (80%) of the soil (core) samples, 238U was lower than 100 Bq per kg soil (the lowest was 8.8 Bq per kg soil), even in locations with intensive use of DU ammunitions (Papastefanou, 2002) (table 7). Other studies did not observe the presence of DU in soil samples collected randomly all over Kosovo (Uyttenhove et al., 2002).
Very low concentrations of DU were detected in plant material (bark, lichens, mosses). DU was mostly absent in water samples (Di Lella et al., 2004; Popovic et al., 2008), with very low concentrations of DU detected only in a few samples. The detection limit in water was 0.22 mBq/L for U-238 and U-234 and 0.022 mBq/L for U235 and U-236 (Jia et al., 2006; Jia et al., 2004). In general, the concentrations of DU detected in environmental samples in areas with intensive use of DU ammunition, except for very localized hotspots, was much lower than DU concentrations predicted by scenarios based on assumed releases of DU from military activities and conservative assumptions. It should be noted that even soil concentrations of DU estimated with a conservative scenario (6 mg DU/kg) are within the typical concentration range of natural U in soil (UNEP/UNCHS, 1999).
Since DU has a much lower radioactivity as compared to natural U and U-containing ores, it is generally agreed that the chemical toxicity of U is the major hazard descriptor regarding assessment of health risk due to potential exposures to DU (UNEP, 2001, 2002, 2003, 2007; UNEP/UNCHS, 1999; WHO, 2001, 2003b). SCHER agrees with this concept. Therefore, the toxicity data on natural U can be applied to assess DU since the chemistry and the chemical toxicology of isotopes are identical. Human health risk due to chemical toxicity and radiation from U and DU only occur when the uranium is ingested or inhaled.
The human toxicity of U is comparatively well studied; the major target organ for soluble U salts is the kidney. Both in rodents and in rabbits, repeated administration of U with drinking water gave NOAELs or LOAELs of 60μg/kg bw/day based on subtle histopathological changes in the kidney. These NOAELs/LOAELs have been transformed in tolerable daily intake for natural U with an uncertainty factor of 100 to give a TDI of 0.6 μg/kg bw per day. Since DU shows an identical toxicity to that of natural U, this TDI is also applicable to DU.
As alpha particles emitted from DU have a very limited range in tissue, DU is not a significant external radiation hazard. Therefore, health effects expected from external radiation caused by DU are limited to unrealistic direct skin contact scenarios. Intake of DU from the environment after use of DU ammunition could not be demonstrated and environmental concentrations of DU, except very close to deposited penetrators and tanks hit, are very low. SCHER therefore agrees with the conclusion of UNEP, IAEA and others that environmental and human health risks due to a potential widespread distribution of DU are not expected due to the very limited exposure to DU as compared to background exposures to natural U (EU-EURATOM, 2001; UNEP, 2001, 2002, 2003, 2007; UNEP/UNCHS, 1999; WHO, 2001, 2003b). Higher exposures to DU dust will only occur when entering vehicles hit by DU ammunition shortly after the hit, and in combat situations when in close proximity to a tank hit by DU ammunition. Therefore, vehicles hit by DU should be made inaccessible to the general public and be properly disposed. Used DU ammunition should also be collected and properly disposed.
In case you wanted something newer than the WHO report wheatfield
Last edited by gokenin; 08-02-2012 at 06:36 PM.
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