The Ministry of Defence has announced a fresh round of depleted uranium weapons testing in south west Scotland.
The firing range at Dundrennan is to be used for DU tests
The Challenger tank ammunition will be fired at the Dundrennan range in Kirkcudbrightshire.
The trials involving the DU shells will take place over the next five days in order to carry out safety checks needed for military operations.
The MoD said that only a small amount of the ammunition would be used and full monitoring would take place.
Depleted uranium is extremely dense and hard, and is used for armour-piercing bullets or shells.
Fears about its health implications led to a study by the World Health Organisation in 2001 which concluded it posed only a small contamination risk.
However, there have been claims to the contrary from the families of military personnel who have served in conflicts where it has been used.
The tests in southern Scotland will be conducted by the defence research agency, QinetiQ.
Has a reduced proportion of isotope Uranium-235
Less radioactive than natural uranium and very dense
Military uses include defensive armour plating, armour-penetrating ordnance
Can be inhaled as dust or ingested in contaminated food and water near impact sites
Used in Iraq, the former Yugoslavia
Thousands of DU rounds have been fired into the Solway Firth from the south of Scotland range over more than two decades.
However, the latest testing programme is the first for five years.
A short statement from the MoD said that public safety precautions were in place.
"Agencies and regulatory bodies responsible for health and safety and environmental protection have agreed the arrangements," it said.
"Comprehensive environmental monitoring programmes involving air, water, and soil sampling, have been in place at and around Kirkcudbright since the beginning of the DU munitions trials.
"The findings continue to show that DU does not pose a significant risk to the environment or to members of the public or site personnel."
Campaign groups continue to oppose the use of depleted uranium shells.
They say that they are both chemically toxic and radiologically hazardous.
They have also voiced concerns about the long-term risks to health and the environment.