Doctors in Afghanistan say rates of some health problems affecting children have doubled in the last two years.
Some scientists say the rise is linked to use of weapons containing depleted uranium (DU) by the US-led coalition that invaded the country in 2001.
A Canadian research group found very high levels of uranium in Afghans during tests just after the invasion.
A US forces spokesman denied its weapons were affecting the health of Afghans or the country's environment.
But claims made in the BBC World Service One Planet programme suggest the invasion may have left an unwelcome legacy for the country's environment and the health of its people.
Doctors in Kabul and Kandahar showed data indicating that the incidence of a number of health conditions, including birth defects, has doubled in under two years.
"We have premature births and malformations," said one doctor, who wished to remain anonymous, in one of the main maternity and neo-natal hospitals in the country.
"Malformations include neural tube defects and malformation of limbs; for example, the head is smaller than normal, or the head is larger than normal, or there is a big mass on the back of the baby.
"We don't know what is the cause of these malformations."
Heavy metal
The Canada-based Uranium Medical Research Centre (UMRC) believes the cause might be depleted uranium.
In 2002 and 2003 the group ran programmes analysing urine from Afghans.
In some, it found levels of uranium hundreds of times greater than in Gulf War veterans.
Asaf Durakovic, URMC's president and a former US army adviser, believes that exposure to DU weapons may have brought a rise in birth defects as well as "symptoms of muscular-skeletal pains, immune system disorders, lung disease, and eventually cancer".
Depleted uranium and natural uranium contain different ratios of two isotopes of the metal.
So scientists can tell whether a person has been exposed to the natural form, or to DU.
DU is used in armour-piercing shells because its density means it can penetrate further than other metals.
Dr Durakovic said his research showed that in Afghanistan, coalition forces had also used DU in "bunker buster" bombs, which can penetrate tens of metres into the soil.
"In Afghanistan it has to be... a weapon that destroys not only bunkers or caves, but also penetrates through the soil and through the fragile environment of the mountains."
Strange fruit
Villagers near the Tora Bora mountains, scene of a massive coalition attack in 2001 aimed at forcing Osama bin Laden out of a cave complex where he was believed to be hiding, suspect the bombs brought an increase in diseases and other problems.
DEPLETED URANIUM
- 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
"There was a strange smell, and most of the trees here did not yield fruit," recounted Yusuf Khan.
Another villager, Bakhtawar, said: "There were three or four babies born in our area whose arms and legs and faces were not normal; they were malformed."
But Faizullah Kakar, Afghanistan's deputy health minister, countered: "Health defects are common in Afghanistan.
"We want to find out if it is nutritional deficiency or environmental contamination with certain radiation that is doing it."
Disputed claims
The US military rejects claims that it used DU-containing bunker busters in Afghanistan.
It also denies allegations that the weapons it used in Afghanistan are affecting health and the environment.
"We don't use depleted uranium in Afghanistan; we don't have a requirement to use that," said Major Chris Belcher, spokesman for the coalition forces.
But he said such weapons might have been used in the past.
"I don't have any knowledge of what might have been used in 2001 and 2002. If there was an armour threat, the DU rounds would have been used to counter that threat."
Dr C Ross Anthony from the Rand Corporation, the US think-tank, suggested use of DU ordnance would have been light in Afghanistan.
"With very few of them (DU weapons) being used, it is hard for me to imagine that much of a real environmental problem exists," he said.
What next?
Some scientific experts suggested performing further research into the alleged damage caused by weapons used in the country.
But officials in Afghanistan's newly established National Environmental Protection Agency said they did not have the necessary equipment or expertise to investigate properly.
And Chris Alexander from the United Nations Assistance Mission for Afghanistan (UNAMA) acknowledged it was a concern, but said: "We have no idea what the scale is, nor do we have special knowledge about environmental implications."
Asaf Durakovic would prefer that concrete measures be taken now.
"The best thing is to relocate the population; people have to be moved from the areas that have been highly contaminated to safe areas to provide medical testing and medical care."
Following the use of DU weapons in Iraq and the Balkans, the World Health Organization (WHO) researched the impact on health and the environment.
It concluded, as did a 2001 European Union enquiry into the Balkans conflict, that DU posed little threat.
A senior WHO official told One Planet it had not received any request from Afghan authorities to investigate the current situation.