16 | New Scientist | 19 February 2022THE maker of a controversial
depleted uranium weapon used
by the US Army has said that it is
ceasing production of the munition.
Depleted uranium (DU) is an
extremely strong and dense metal
that is able to pierce armoured
vehicles, making it the prime choice
as the chief anti-tank ammunition
used by the M1 Abrams, the US
Army’s main battle tank. However,
it is toxic and radioactive, and
campaigners linking DU to cancer
and other health issues have long
called for it to be phased out.
That may now happen. During
a quarterly earnings update on
27 January, Kathy Warden, the
CEO of defence company Northrop
Grumman, unexpectedly announced
that the firm will stop producing the
M829A4 DU round within a year.
“We are looking to the future
and the decision to cease production
boils down to sustainability,” Jarrod
Krull at Northrop Grumman told
New Scientist. He declined to
explain further, but said the decision
wasn’t made for financial reasons.
The DU component used in the
anti-tank round is produced for
Northrop Grumman by another firm,
Aerojet Rocketdyne, and it is unclear
if it will continue to do so. The US
Army put out a request for an
alternative supplier in January.
Only the UK and US have admitted
using DU rounds in action, but other
nations, such as Russia, have them.
Some have long renounced them –
Belgium banned them in 2009.
“Generally, the battle to stigmatise
depleted uranium has been won,”
says Doug Weir at the Conflict and
Environment Observatory, a UK
non-profit organisation.
The scientific consensus is that
the risk to surrounding populations
from DU is low, but Weir says the
weapons now appear to be in a
category with cluster bombs and
land mines as being unacceptable
for some investors. ❚Military technologyDavid HamblingUS Army supplier
to ditch depleted
uranium roundsNews
PEOPLE with high blood
pressure may benefit from
practising yoga, according
to a large observational study
carried out in the US.
About one-third of adults
globally have high blood
pressure, which increases the
risk of having a heart attack
or stroke. Physical activity is
known to lower blood pressure
not only during heartbeats
(systolic pressure) but also
in between beats (diastolic
pressure). However, many
people have trouble sticking
to exercise regimes.
Yoga tends to be more
sustainable than many other
forms of exercise because
it is gentle on the joints, can
be done with others and helps
to relax the mind.
Several clinical trials have
found that yoga lowers blood
pressure, especially when it
incorporates breathing exercises
and meditation. But it has been
unclear whether these results
translate to real life.
To find out if yoga helps
to reduce blood pressure in
real-world settings, NadiaPenrod at the University of
Pennsylvania and Jason Moore
at the Cedars-Sinai Medical
Center in Los Angeles studied
the electronic health records
of 1355 people aged 18 to 79 in
south-east Pennsylvania whose
clinical notes said they practised
yoga at least once a week.
They compared each of these
people with at least three other
individuals who had similar
characteristics in terms of
age, sex, race, postal code,body mass index, alcohol
use, smoking status and use
of blood pressure-lowering
medications, but who had
no mention of practising
yoga in their clinical notes.
On average, the people
who practised yoga had a
systolic blood pressure that
was 2.8 millimetres of mercury
(mmHg) lower and a diastolic
blood pressure that was
1.5 mmHg lower than those
who didn’t do yoga (BMC
Public Health, doi.org/hgj4).
This reduction probably
wouldn’t make a massive
difference to most people in
the study, since they tended
to be young, healthy women
who already had normal blood
pressures, says Mark Nelson
at the University of Tasmania
in Hobart, Australia.
However, if average blood
pressure declined by this
much across a population,
it would prevent a significant
number of heart attacks and
strokes, he says.
For example, a 2015 study
discovered that reducing the
systolic blood pressure of all
middle-aged adults in the
US by an average of 2 mmHg
would prevent more than12,000 heart attacks and
7000 strokes each year.
Based on the latest study,
we can’t say for sure that
yoga lowers blood pressure
because there may be other
explanations for the findings,
says Geoff Head at the Baker
Heart and Diabetes Institute
in Melbourne, Australia.
For example, people who
do yoga may have lower blood
pressure because they tend to
have better diets, not because
of the yoga itself, he says.
It is also important that
yoga isn’t seen as a substitute
for blood pressure-lowering
medications, which typically
reduce systolic blood pressure
by more than 5 mmHg,
according to Head.
Nevertheless, yoga is likely
to assist with lowering blood
pressure if it encourages
exercise-shy people to start
moving, says Nelson.
“The greatest benefit is
getting the sedentary to
do something rather than
increasing exercise in someone
who does it regularly,” he says. ❚There could be
real-world health
benefits to yogaHealthAlice KleinDEEP
OL
BYPLAINPICTUREYoga at least once a week may
help to lower blood pressure
“ Even a modest fall in
blood pressure across
a population would
prevent many strokes”