This article about actinides in the environment is about the sources, environmental behaviour and effects of actinides in the environment.
Thorium in the environment
In India a large amount of thorium ore can be found in the form of beach sand.[1]
Uranium in the environment
See also Depleted_uranium#Safety_and_environmental_issues and Depleted_uranium#Health Concerns
High profile sources
The potential danger of exposure to depleted uranium has received widespread publicity because of the use of DU munitions in the 1991 Gulf War and 1999 Kosovo War, as well as current conflicts [2]. "A total of just over 290 metric tons of DU projectiles were fired by the US during the Gulf War (comapred [sic] to 9 tons in Kosovo and 3 tons in Bosnia and Herzegovina)." p68 UNEP study, 2003, [3] The potential long-term effect on people living in areas where DU munitions were used, has also caused some concern.
Fragments from projectile DU munitions could cause substantial inhalation exposure risks in certain circumstances if the exposure was high. [4] Those risks have been associated with a number of health concerns, many of which are controversial.
Dispersion of uranium
- Uranium metal can disperse into the air and water, United Nations Environment Programme (UNEP) study [5] says in part:
- "The most important concern is the potential for future groundwater contamination by corroding penetrators (ammunition tips made out of DU). The munition tips recovered by the UNEP team had already decreased in mass by 10-15% in this way. This rapid corrosion speed underlines the importance of monitoring the water quality at the DU sites on an annual basis."
Combustion
Studies of depleted uranium aerosol exposure suggest that uranium combustion product particles would quickly settle out of the air [6] and thus could not affect populations more than a few kilometers from target areas. [7]
The U.S. has admitted that there have been over 100 "friendly fire" incidents in which members of the U.S. military have been struck by DU munitions, and that an unknown number have been exposed to DU via inhalation of combustion products from burning DU munitions.
Corrosion
It has been reported that the corrosion of uranium in a silica rich aqueous solution forms both uranium dioxide and uranium trioxide. [8]
In pure water, schoepite {(UO2)8O2(OH)12.12(H2O)} is formed [9] in the first week and then after four months studtite {(UO2)O2·4(H2O)} was formed. A report on the corrosion of uranium metal has been published by the Royal Society. [10] [11]
Health effects
Studies have shown that the use of DU ammunition has no measurable detrimental health effects, either in the short or long term. The International Atomic Energy Agency reported in 2003 that, "based on credible scientific evidence, there is no proven link between DU exposure and increases in human cancers or other significant health or environmental impacts," although "Like other heavy metals, DU is potentially poisonous. In sufficient amounts, if DU is ingested or inhaled it can be harmful because of its chemical toxicity. High concentration could cause kidney damage." [12]
A two year study headed by Al Marshall of Sandia National Laboratories analyzed some health effects associated with accidental exposure to depleted uranium during the 1991 Gulf War, but did not consider any nonradiological reproductive toxicity, developmental toxicity, or immunological effects. Marshall’s study concluded that the reports of serious health risks from DU exposure are not supported by veteran medical statistics and were consistent with earlier studies form Los Alamos and the New England Journal of Medicine [13].
In the Balkans war zone, an absence of problems is seen by some as evidence of DU muntions' safety: "Independent investigations by the World Health Organization, European Commission, European Parliament, United Nations Environment Programme, United Kingdom Royal Society, and the Health Council of the Netherlands all discounted any association between depleted uranium and leukemia or other medical problems." [14]
However in 2004, the U.K. Pensions Appeal Tribunal Service granted a single disability claim to a Gulf War soldier who attributed his aching joints and children's health problems to depleted uranium. This claim was vigorously disputed by the MoD. [15],[16].
Some studies have indicated that DU passes into humans more easily than previously thought after battlefield use. [17][18]
Birth defects
Most scientific studies have found no link between uranium and birth defects, but a few have found a link.
One study concluded that epidemiological evidence is consistent with an increased risk of birth defects in the offspring of persons exposed to DU.[19]. Environmental groups and others have expressed concern about the health effects of depleted uranium[20], and there is significant debate over the matter. Some people have raised concerns about the use of this material, particularly in munitions, because of its mutagenicity [21], teratogenicity [22],[23] in mice, and neurotoxicity [24], and its suspected carcinogenic potential. Such issues are of concern to civilians and troops operating wherever depleted uranium is used, and to those who live there afterwards, or who breathe the air or drink the water from that place [25].
Several sources have attributed the increase in the rate of birth defects in the children of Gulf War veterans and in Iraqis to depleted uranium inhalation exposure[26],[27]. A 2001 study of 15,000 February 1991 U.S. Gulf War combat veterans and 15,000 control veterans found that the Gulf War veterans were 1.8 (fathers) to 2.8 (mothers) times more likely to have children with birth defects[28]. In a study of U.K. troops, "Overall, the risk of any malformation among pregnancies reported by men was 50% higher in Gulf War Veterans (GWV) compared with Non-GWVs". The conclusion of the study stated " We found no evidence for a link between paternal deployment to the Gulf war and increased risk of stillbirth, chromosomal malformations, or congenital syndromes. Associations were found between fathers' service in the Gulf war and increased risk of miscarriage and less well-defined malformations, but these findings need to be interpreted with caution as such outcomes are susceptible to recall bias. The finding of a possible relationship with renal anomalies requires further investigation. There was no evidence of an association between risk of miscarriage and mothers' service in the gulf."[29].
Plutonium in the environment
Plutonium has been released into the environment in aqueous solution from nuclear plants, the chemistry of this plutonium is different to that of the metal oxides formed from nuclear bomb detonations.
Another potential source of plutonium being introduced into the environment is the reentry of artificial satellites containing atomic batteries.
Americium in the environment
Americium often enters landfills from discarded smoke detectors. There is no special requirement for their disposal in many municipalities.