Depleted uranium is, even in small quantities, extremely heavy. Shells tipped with depleted uranium are thus able to pierce even the armored shells of tanks.

That is why depleted uranium is used in the manufacture of munitions.

But depleted uranium shells also have a major defect: They emit minuscule quantities of radiation. There is also a fear that the shells themselves might be toxic because uranium is a heavy metal and can harm the environment.

These types of automatic cannon shells were used in large quantities by the United States when NATO forces intervened in the conflict in the former Yugoslavia. About 30,000 of these shells were reportedly used in Kosovo.

Recently, armed forces personnel from Europe who served in the conflict and who have been diagnosed as having either leukemia or cancer have voiced their suspicions that depleted uranium shells caused their conditions. Some nations, including Italy, have called upon NATO to freeze the use of such munitions.

In response to this, an ambassadorial-level NATO council has decided to file a report with the United Nations on how depleted uranium munitions were actually used in the conflict. However, because of opposition from countries including the United States and Britain, the council has deferred a decision on a freeze on the use of such weapons.

We wonder whether it is necessary for the United States, which possesses overwhelmingly powerful armed forces, to rely on weapons that create anxiety about the after-effects among its returned servicemen and which leave radioactivity in the environment where they are used.

Among returned U.S. military personnel who served in the Persian Gulf War, too, there have been many who complain about health problems, lumped under the blanket term ``Gulf War syndrome.''

Suspicions were raised about the effects of chemical weapons and depleted uranium munitions, but the U.S. Department of Defense emphasized that no direct connection has been recognized in either case.

Although experts from the World Health Organization denied a direct connection between the shells and leukemia in this instance, they did state that, theoretically, prolonged absorption of minute particles of depleted uranium could lead to a higher probability of contracting lung cancer.

It is possible to make anti-tank munitions that do not use depleted uranium. Would it not, therefore, be possible for NATO to choose a safer path by totally banning the use of depleted uranium munitions?

There is also a need to investigate the extent of contamination in regions where depleted uranium shells were fired in the conflict. There is soil in Kosovo where higher-than-normal readings of radioactivity have been detected. If uranium particles remain, it may become necessary to remove the contaminated soil.

It is also important, through cooperation with U.N. bodies and others, to investigate from a medical perspective the relationship between depleted uranium and illness. Clarifying any causal relationship is indispensable in the event that consideration is given to making compensatory payments to returned servicemen.

Exposure to radiation from depleted uranium shells can be considered quite low. In contrast to what we know of the effects of intense radiation at the time of a nuclear explosion, a lot remains to be established about low-dose absorption. It is not easy to clearly establish a link between health and low-dose aftereffects. That is part of the reason that the United States and Britain deny any relationship.

Of course depleted uranium munitions, including their manufacture and stockpiling, should be banned if any causal relationship is established.

Further, even if after investigation no causal relationship is established, unless an unequivocal pronouncement can be made about their safety, it seems unwise to tolerate depleted uranium munitions.

This subject is not without implications for Japan. U.S. forces in Japan have mistakenly fired depleted uranium shells at their firing range on Torishima islet in Okinawa Prefecture. It appears, moreover, that some of the shells are currently stored at Kadena Air Base.

The government should immediately and strongly press for the United States to disclose information on the current situation regarding storage within Japan of depleted uranium munitions.