Properties, use and health effects of depleted uranium (DU): a general overview.

Depleted uranium (DU), a waste product of uranium enrichment, has several civilian and military applications. It was used as armor-piercing ammunition in international military conflicts and was claimed to contribute to health problems, known as the Gulf War Syndrome and recently as the Balkan Syndrome. This led to renewed efforts to assess the environmental consequences and the health impact of the use of DU. The radiological and chemical properties of DU can be compared to those of natural uranium, which is ubiquitously present in soil at a typical concentration of 3 mg/kg. Natural uranium has the same chemotoxicity, but its radiotoxicity is 60% higher. Due to the low specific radioactivity and the dominance of alpha-radiation no acute risk is attributed to external exposure to DU. The major risk is DU dust, generated when DU ammunition hits hard targets. Depending on aerosol speciation, inhalation may lead to a protracted exposure of the lung and other organs. After deposition on the ground, resuspension can take place if the DU containing particle size is sufficiently small. However, transfer to drinking water or locally produced food has little potential to lead to significant exposures to DU. Since poor solubility of uranium compounds and lack of information on speciation precludes the use of radioecological models for exposure assessment, biomonitoring has to be used for assessing exposed persons. Urine, feces, hair and nails record recent exposures to DU. With the exception of crews of military vehicles having been hit by DU penetrators, no body burdens above the range of values for natural uranium have been found. Therefore, observable health effects are not expected and residual cancer risk estimates have to be based on theoretical considerations. They appear to be very minor for all post-conflict situations, i.e. a fraction of those expected from natural radiation.

Isotopic composition and origin of uranium and plutonium in selected soil samples collected in Kosovo.

Soil samples collected from locations in Kosovo where depleted uranium (DU) ammunition was expended during the 1999 Balkan conflict were analysed for uranium and plutonium isotopes content (234U, 235U, 236U, 238U, 238Pu, (239 + 240)Pu). The analyses were conducted using gamma spectrometry (235U, 238U), alpha spectrometry (238Pu, (239 + 240)Pu), inductively coupled plasma-mass spectrometry (ICP-MS) (234U, 235U, 236U, 238U) and accelerator mass spectrometry (AMS) (236U)). The results indicated that whenever the U concentration exceeded the normal environmental values (approximately 2 to 3 mg/kg) the increase was due to DU contamination. 236U was also present in the released DU at a constant ratio of 236U (mg/kg)/238U (mg/kg) = 2.6 x 10(-5), indicating that the DU used in the ammunition was from a batch that had been irradiated and then reprocessed. The plutonium concentration in the soil (undisturbed) was about 1 Bq/kg and, on the basis of the measured 238Pu/(239 + 240)Pu, could be entirely attributed to the fallout of the nuclear weapon tests of the 1960s (no appreciable contribution from DU).

Database of natural matrix reference materials (NMRM) for organic constituents.

The International Atomic Energy Agency maintains a database of internationally available certified reference materials (CRM) of natural matrices. This database is periodically updated, and presently documents nearly 25,000 measurands in 1,700 materials. The organic constituents are classified in five major groups of analytes aliphatic and aromatic hydrocarbons (A), chlorinated hydrocarbons (B), pesticides (C), organometallic compounds (D) and other organic constituents (nutrients, etc.) (E). The matrices include natural materials such as body fluids, food products, soils, and sediments, terrestrial (e.g. plants), and anthropogenic products (e.g. dust, fly ash). These five organic groups of analytes encompass more than 2000 measurands for 420 different analytes in 230 materials. Of these measurands, 1,682 (68%) are certified, and 768 (32%) are provided as informational values. Within each major group of analytes, measurands reported as informational values accounted for: A (35%); B (35%); C (26%); D (10%), and E (22%). The high proportion of informational values (i.e. non-certified values) for A, B, and C, compares well with a similar but undesirable situation faced in the nineteen-seventies in the inorganic area when simultaneous multielement techniques became available. In the case of D and E, it appears that mostly targeted analytes are measured, leading to a cohesive certification profile. Although the IAEA database is not equally comprehensive for all groups of analytes cited above, it can still serve as an useful indicator of the status of organic constituents in RMs.

IAEA Internet database of natural matrix reference materials.

The International Atomic Energy Agency maintains a database on internationally available certified reference materials of natural origin. The database was updated in 1998 and prepared for an Internet implementation. A user-friendly structure was created, providing two main pathways for browsing, either according to the matrix classification or the producer's name. The database presently contains over 20,000 values for 480 measurands and 1085 reference materials from 43 different producers. Most of the materials entered contain values for trace and minor elements (66%).