New Delhi, 03
of our regular contributors has sent in the following story which
appeared in the New Scientist (www.newscientist.com)
of 15 April 2003. It throws up disturbing questions about chemical
and radio active materials being used by the coalition forces in
Iraq. Specifically it highlights the use of 'depleted uranium' (DU)
which is both radioactive and toxic. 'It
is used to make the tips of armour-piercing shells because it is
extremely dense: 1.7 times as dense as lead. Also, unlike other
heavy metals that tend to flatten, or mushroom, upon impact, DU has
the ability to "self-sharpen" as material spread out by
the impact ignites and burns off as the munition pierces its target.'
tanks and vehicles litter the Iraqi countryside. Ruined buildings
dominate towns and cities. Many were blown to pieces by shells
tipped with depleted uranium, a material that the US and Britain say
poses no long-term health or environmental risks. But many Iraqis,
and a growing band of scientists, are not so sure.
week, the UN Environment Programme (UNEP) announced it wanted to
send a scientific team into Iraq as soon as possible to examine the
effects of depleted uranium (DU). People's fears that DU leaves a
deadly legacy must be addressed, says UNEP. Some scientists go
further. Evidence is emerging that DU affects our bodies in ways we
do not fully understand, they say, and the legacy could be real.
is both radioactive and toxic. Past studies of DU in the environment
have concluded that neither of these effects poses a significant
risk. But some researchers are beginning to suspect that in
combination, the two effects could do significant harm. Nobody has
taken a hard look at the combined effect of both, says Alexandra
Miller, a radiobiologist with the Armed
Forces Radiobiology Research Institute in Bethesda, Maryland.
"The bottom line is it might contribute to the risk."
is not alone. The idea that chemical and radiological damage are
reinforcing each other is very plausible and gaining momentum, says
Carmel Mothersill, head of the Radiation and Environmental Science
Centre at the Dublin Institute of Technology in Ireland. "The
regulators don't know how to handle it. So they sweep it under the
"Before the dust settles", the New Scientist
editorial on this story here.
by-product of the uranium enrichment process, DU is chemically
identical to natural uranium. But most of the 235 isotope has been
extracted leaving mainly the non-fissionable 238 isotope. It is used
to make the tips of armour-piercing shells because it is extremely
dense: 1.7 times as dense as lead. Also, unlike other heavy metals
that tend to flatten, or mushroom, upon impact, DU has the ability
to "self-sharpen" as material spread out by the impact
ignites and burns off as the munition pierces its target.
the Gulf war in 1991, the US and Britain fired an estimated 350
tonnes of DU at Iraqi tanks, a figure likely to be matched in the
course of the current conflict. In the years since then, doctors in
southern Iraq have reported a marked increase in cancers and birth
defects, and suspicion has grown that they were caused by DU
contamination from tank battles on farmland west of Basra.
the Pentagon and the Ministry of Defence point out, this claim has
not been substantiated. Iraq did not allow the World Health
Organization to carry out an independent assessment. Given its low
radioactivity and our current understanding of radiobiology, DU
cannot trigger such health effects, the British and American
what if they are wrong? Though DU is 40 per cent less radioactive
than natural uranium, Miller believes that its radiological and
toxic effects might combine in subtle, unforeseen ways, making it
more carcinogenic than thought. It's a controversial theory, but one
for which Miller has increasing evidence.
is "genotoxic". It chemically alters DNA, switching on
genes that would otherwise not be expressed. The fear is that the
resulting abnormally high activity in cells could be a precursor to
while the chemical toxicity of DU is reasonably well established,
Mothersill points out that the radiological effects of DU are less
clear. To gauge the risk from low-dose radiation, researchers
extrapolate from tests using higher doses. But the relationship
between dose and effect is not linear: at low doses radiation kills
relatively fewer cells. And though that sounds like good news, it
could mean that low radiation is having subtle effects that go
unnoticed because cells are not dying, says Mothersill.
has found one way this may happen. She has discovered the first
direct evidence that radiation from DU damages chromosomes within
cultured cells. The chromosomes break, and the fragments reform in a
way that results in abnormal joins (Military Medicine, vol 167, p
120). Both the breaks and the joins are commonly found in tumour
crucially, she has recently found that DU radiation increases gene
activity in cultured cells at doses of DU not known to cause
chemical toxicity (Molecular and Cellular Biochemistry, in press).
The possible consequences are made all the more uncertain because no
one knows if genes switched on by DU radiation enhance the damage
caused by genes switched on by DU's toxic effects, or vice versa.
"I think that we assumed that we knew everything that we needed
to know about uranium," says Miller. "This is something we
have to consider now when we think about risk estimates."
Britain's Royal Society briefly referred to these synergistic
effects in its report last year on the health effects of DU
munitions. "There is a possibility of damage to DNA due to the
chemical effects being enhanced by the effects of the alpha-particle
irradiation." But it makes no recommendations for future
research to evaluate the risks.
points to another reason to be concerned about DU: the so-called
"bystander effect". There is a growing consensus among
scientists that radiation damages more than just the cells it
directly hits. In tests using equipment that allows single cells to
be irradiated by individual alpha particles, gene expression
increases both in irradiated cells, and in neighbouring cells that
have not been exposed. "At high doses, 'bystander' is not an
issue because you are killing so many cells. But at low doses that's
not really true," says Miller. There is a danger that
specifically looking for this effect could miss an important source
body of research has also emerged over the past decade showing that
the effects of radiation may not appear immediately. Damage to genes
may be amplified as cells divide, so the full consequences may only
appear many generations after the event that caused it.
while the chemical toxicity of DU itself is more clear-cut, the
possibility remains that there may still be some unforeseen
synergistic effects at a genetic level. Other heavy metals, such as
tungsten, nickel and cobalt are similarly genotoxic. When Miller and
her team exposed human cells to a mixture of these metals,
significantly more genes became activated than when the cells were
exposed to the equivalent amount of each metal separately (Molecular
and Cellular Biochemistry, in press).
and Mothersill say that recommended safe radiation limits are often
based on the idea that only irradiated cells will be affected, and
ignore both the bystander effect and the possible amplification over
the generations. "Nothing should be written in stone when it
comes to risk assessment," agrees Michael Clark at Britain's
National Radiological Protection Board. But even if there were a
case for re-evaluating the dosimetry for low-dose radiation, he says
we should be cautious of the significance of Miller's lab-based
research. "An in vitro effect is not a health effect."
says Clark, everyone has traces of natural uranium in their bodies.
"If there was some sort of subtle low-dose effect I think we
would have seen it," he says. Because none has shown up in
epidemiological studies, it seems unlikely there are any health
effects associated with DU, which is less radioactive. But Miller is
not convinced. While most people have small amounts of uranium in
their bodies, she says no studies have been done to see whether this
contributes to cases of cancer in society at large.
military tends to dismiss such hazards as being of only theoretical
significance, at least when it comes to civilians. According to the
Pentagon, the only risk of exposure is during combat, when DU shells
hit hard targets and the metal ignites. This creates clouds of
uranium oxide dust that can be breathed in. But heavy oxide
particles quickly settle, it says, limiting the risk of exposure.
"A small dust particle is still very heavy," says Michael
Kilpatrick of the US Deployment Health Support Directorate. "It
stays on the ground."
sounds reassuring until you read UNEP's latest report on DU left
over from conflicts in former Yugoslavia in the mid-1990s. Last
month, a team of experts collaborating with the International Atomic
Energy Agency, WHO and NATO concluded that DU poses little risk in
Bosnia although it can still be detected at many sites. Just 11
tonnes was fired in that conflict.
evidence that DU may be moving through the ground and could
contaminate local water supplies should be investigated further,
UNEP says. And on rare occasions, wind or human activity may raise
DU-laden dust that local people could inhale. The Royal Society
admits that localised areas of DU contamination pose a risk,
particularly to young children, and should be cleared up as a
priority. They also recommend the environmental sampling of affected
areas (see Royal Society Reports on DU, 2002", below).
evidence is partly why UNEP is keen to study DU fired during the
present conflict in Iraq. Assessments in former Yugoslavia were made
up to seven years after DU weapons were used, UNEP admits, and a
more immediate study in Iraq would give us a much better
understanding of how DU behaves in the environment. Any hazards such
a study identifies could be dealt with immediately, says UNEP. And
even now, an investigation in Iraq could reveal risks remaining from
DU fired during the Gulf war in 1991.
Show Ill Effects
are also appearing in the argument that DU munitions have not proven
harmful even to troops. In the 1991 war, more than 100 coalition
troops were exposed to DU after being accidentally fired on by their
own forces. The majority inhaled uranium oxide, while the rest
suffered shrapnel injuries. Some still have DU in their bodies.
Britain and America point out that none has developed cancers or
kidney problems, as might have been expected if DU posed a long-term
researchers at the Bremen Institute for Prevention Research, Social
Medicine and Epidemiology in Germany have found that all is not well
with the veterans. Last month they published results from tests in
which they took blood samples from 16 of the soldiers, and counted
the number of chromosomes in which broken strands of DNA had been
incorrectly repaired. In veterans, these abnormalities occurred at
five times the rate as in a control group of 40 healthy volunteers
(Radiation Protection Dosimetry, vol 103, p 211). "Increased
chromosomal aberrations are associated with an increased incidence
of cancers," says team member Heike Schröder. The damage
occurred, they say, because the soldiers inhaled DU particles in
NRPB is unconvinced. "It is possible that exposure to
significant amounts of DU could cause excess chromosome aberrations,
but this study has technical flaws," says Clark. "There
are no proper controls to compare results with soldiers who were not
exposed to DU. And some of the reported excess aberrations are well
known to be linked to chemicals rather than radiation."
Decision To Make
whether DU is to blame will be tough. Independent research may
confirm that rates of cancer have increased in the Iraqi population.
But the Iraqi government has used chemical weapons on its own people
that can produce the same outcome, and it is impossible to know for
sure who may have been exposed. Soldiers may similarly have been
exposed to chemicals in 1991. The only way to resolve the issue is
more research, says Dudley Goodhead, director of Britain's Medical
Research Council's Radiation and Genome Stability Unit at Harwell,
near Oxford. "It's something important that needs to be
admits it is entirely possible that DU contamination is safe. But
many of the scientific investigations into DU have only just begun,
and their results will be long coming. "None of this has been
looked at or even thought about it until the last few years,"
she says. As the dust begins to settle in Iraq, it remains to be
seen when the ravages of war will end.
Society Reports on DU, 2002 – Conclusions
soldiers have a negligible risk of dying of cancer caused by
radiation from battlefield DU. It will be undetectable above the
risk of dying from cancer over a normal lifetime. Soldiers
should not suffer adverse effects on the kidney or other organs.
few soldiers, for instance those who clean up vehicles struck by
DU, may have an excess risk of lung cancer and may develop
short-term kidney damage.
living in areas where DU was deployed have a negligible risk of
developing cancers as a result of inhaling DU resuspended in the
air. But it is uncertain how much DU is inhaled in years
following a conflict. Most people should not suffer any effects
on kidney function from inhaled DU.
of DU from contaminated water and food, and from soil, will be
highly variable and may be significant in some cases: for
example, children playing in areas where DU shells have
Society Reports On DU, 2002 – Recommendations
epidemiological studies of soldiers exposed to DU, and
environmental sampling, particularly of water and milk, should
be undertaken. Information about DU levels should be given to
local populations, and contaminated areas cleaned up.
veterans exposed to high levels of DU should be identified and
independently evaluated. An independent study of anecdotal
reports of death and illness in US veterans linked to DU is
any future conflict using DU munitions, tests of kidney function
should be completed on soldiers as soon after exposure as
estimates of DU levels in the air around tanks, and models of DU
oxide behaviour during impact, are required. More information is
needed on the bioavailability of DU and titanium products from
munitions, and whether these concentrate in plants and animals