Depleted Uranium Shells Could Help Ukraine. Critics Say It’s Not Worth the Risk.

The United States announced an aid package for Ukraine on Sept. 6 that for the first time included ammunition made with depleted uranium to Ukraine, raising concerns over the material’s potential health and environmental effects.

The munitions — 120-millimeter anti-armor ammunition — are for use in 31 U.S.-provided M1 Abrams tanks, the first of which reached Ukraine in recent days. Britain has also sent Ukraine ammunition made with depleted uranium.

The Pentagon has defended the use of the ammunition, maintaining that it will assist Kyiv’s counteroffensive against Russian forces. But some experts say the health risks posed by depleted uranium outweigh the military benefits. Here is what to know about it:

Ammunition made with depleted uranium can pierce armor.

Depleted uranium is a byproduct of uranium enrichment, the process used to create nuclear fuel. It is only mildly radioactive, but it is extremely dense — almost two and a half times denser than steel and at least one and a half times denser than lead.

The material has some civilian uses, as for instance in medical radiation shields, certain sailboat keels and some airplane parts.

But its main use is in armaments. Depleted uranium can be fashioned into long, thin, dart-like projectiles that can pierce heavily armored vehicles like tanks, said Doug Weir, the research and policy director at The Conflict and Environment Observatory. And the uranium dust created on impact can ignite, potentially consuming the target in fire. The United States has deployed the munitions in prior conflicts, including in the Persian Gulf War and the invasion of Iraq.

The ammunition is “part of an overall trend to send Ukraine more advanced and controversial weaponry,” said Gabriela Iveliz Rosa Hernández, a research associate at the Arms Control Association. “We’ve gone from Javelins and Stingers to Abrams tanks and F-16s in terms of commitment.”

Lingering uranium dust can emit radiation.

Fired shells leave behind finely powdered uranium dust that can contaminate soil. The dust emits alpha radiation, which cannot penetrate skin and is not harmful when outside the body, Mr. Weir said, but when ingested or inhaled, can “essentially dump radiation straight into your lung tissue.”

Wim Zwijnenburg, the humanitarian disarmament project leader for the Dutch peace organization PAX, said that children and pregnant women are the most vulnerable to the dust’s health effects.

The Pentagon has disputed claims that depleted uranium is linked to other significant health or environmental impacts, citing studies by the Centers for Disease Control and Prevention, the World Health Organization and the International Atomic Energy Agency. The Department of Defense also pointed to a study of almost 80 survivors of incidents involving depleted uranium in the gulf war, which did not find any adverse clinical effects linked to the weapons.

But both Mr. Zwijnenburg and Mr. Weir said that there had not been enough research on the long-term effects of depleted uranium munitions to confirm such an assessment.

Unlike cluster munitions, which the United States shipped to Ukraine in July, there is no international treaty banning weapons made with depleted uranium. But opponents of depleted uranium weapons argue that the potential postwar effects on civilians are enough reason to ban them.

Russia calls it ‘a clear sign of inhumanity.’

Dmitri S. Peskov, the spokesman for President Vladimir V. Putin, called the U.S. decision to supply Ukraine with depleted uranium shells “very bad news.” The Russian Embassy in Washington posted a message on Telegram condemning the transfer, calling the decision “a clear sign of inhumanity.”

It is not clear whether Russia uses depleted uranium shells itself, though the state news agency Tass reported in 2018 that a modernized version of its main battle tank had the capacity to fire them. The report cited a Russian military expert, Viktor Murakhovsky, as saying that the shells were kept in special stockpiles rather than in regular arsenals.