SOURCE: THE INDEPENDANT – UK
Children exposed to pesticide in womb twice as likely to be
overweight, refuting idea of sole personal responsibility. Geoffrey
Lean reports
Sunday, 7 September 2008
Pollution can make children fat, startling new research shows. A
groundbreaking Spanish study indicates that exposure to a range of
common chemicals before birth sets up a baby to grow up stout, thus
helping to drive the worldwide obesity epidemic.
The results of the study, just published – the first to link chemical
contamination in the womb with one of the developing world’s greatest
and fastest-growing health crises – carry huge potential implications
for public policy around the globe. They undermine recent strictures
from the Conservative leader, David Cameron, that blame solely the
obese for their own condition.
A quarter of all British adults and a fifth of children are obese –
four times as many as 30 years ago. And so are at least 300 million
people worldwide. The main explanation is that they are consuming
more calories than they burn. But there is growing evidence that diet
and lack of exercise, though critical, cannot alone explain the rapid
growth of the epidemic.
It has long been known that genetics give people different
metabolisms, making some gain weight more easily than others. But the
new study by scientists at Barcelona’s Municipal Institute of Medical
Research suggests that pollution may similarly predispose people to
get fat.
The research, published in the current issue of the journal Acta
Paediatrica, measured levels of hexachlorobenzene (HCB), a pesticide,
in the umbilical cords of 403 children born on the Spanish island of
Menorca, from before birth. It found that those with the highest
levels were twice as likely to be obese when they reached the age of
six and a half.
HCB, which was mainly used to treat seeds, has been banned
internationally since the children were born, but its persistence
ensures that it remains in the environment and gets into food.
The importance of the study is not so much in identifying one
chemical, as in showing what is likely to be happening as a result of
contact with many of them. Its authors call for exposures to similar
pesticides to be “minimised”.
Experiments have shown that many chemicals fed to pregnant animals
cause their offspring to grow up obese. These include organotins,
long employed in antifouling paints on ships and now widely found in
fish; bisphenol A (BPA), used in baby bottles and to line cans of
food, among countless other applications; and phthalates, found in
cosmetics, shampoos, plastics to wrap food, and in a host of other
everyday products.
These pollutants – dubbed “obesogens” as a result of these findings –
are so ubiquitous that almost everyone now has them in their bodies.
Ninety-five per cent of Americans excrete BPA in their urine; 90 per
cent of babies have been found to be exposed to phthalates in the
womb; and every umbilical cord analysed in the new Spanish study was
found to contain organchlorine pesticides such as HCB.
Two American studies have implicated phthalates in obesity in adult
men, but the new research is much more conclusive, and is the first
to show the effects of exposure in the womb, where humans are most
vulnerable.
Dr Pete Myers, one of the world’s leading experts on obesogens, told
The Independent on Sunday last night: “This is very important. It is
the first good study of the effects on the foetus. Its conclusions
are not surprising, given what we know from the animal experiments,
but it firmly links such chemicals to the biggest challenge facing
public health today.”
No one knows how HCB causes obesity. The Spanish scientists speculate
that it may have made the mothers diabetic, which would increase the
chances of their children becoming obese (see graphic, above).
Dr Myers, who is chief scientist at the US-based Environmental Health
Sciences, which helps to increase public understanding of emerging
scientific links, says this is “plausible”, but adds that the animal
experiments point elsewhere. These have shown that obesogens “switch
genes on and off” in the womb, causing stem cells to be turned into
fat cells. The children then grow up with a much greater disposition
to store and accumulate fat.
Whatever the explanation, the research goes some way to undermining
David Cameron’s assertion in a speech this summer that obesity is
purely a matter of “personal responsibility”, a view echoed by his
health spokesman, Andrew Lansley 10 days ago. The Tory leader said
that the obese are “people who eat too much and take too little
exercise”.
Dr Myers calls that “wishful ideological thinking which does not
accord with biological reality”, adding: “We need to discover ways to
reduce exposures to these chemicals so that changing diet and
lifestyle has a chance to work.”
Factors that may pile on the pounds
Why is the world getting so fat? Everyone agrees that people gain
weight by taking in more calories in their food than they burn off
through everyday activities and exercise. But many scientists are
coming to believe that changes in diet and exercise do not
sufficiently explain the rapid growth of the epidemic. As ‘The
Independent on Sunday’ reported last week, there has been no
reduction in physical activity in Britain since 1980, while obesity
rates have quadrupled.
The genetic make-up of a population does not change rapidly enough to
provide an explanation. So the hunt is on for other factors that
might show why more people are gaining weight more easily.
Life before birth. Both overweight and underweight babies are more
likely to grow up fat. So are those born to smokers. Evidence
suggests pollution is also predisposing the unborn to obesity. The
introduction and increase in the use of such chemicals coincides with
the epidemic taking off.
Age of mothers. The chances of becoming obese increase with maternal
age. And the average age of first giving birth has gone up by 2.6
years in Britain since 1970.
Less sleep. Both children and adults are more likely to get fat if
they get too little sleep, partly because they become hungrier.
Average daily sleep has fallen from nine to seven hours over recent
decades.
Temperature. People burn up more calories when they are cold. Central
heating has ensured that they spend most of their time in comfortable
temperatures.
Prescription drugs. Some drugs – including anti-psychotics,
antidepressants and treatments for diabetes – cause people to gain
weight.
Stopping smoking. Though mothers who smoke may make their children
fat, they – and all smokers – are themselves less likely to put on
weight. As the habit has decreased, obesity has soared.
To have your say on this or any other issue visit
www.independent.co.uk/IoSblogs
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