Women who use mobile phones when pregnant are more
likely to give birth to children with behavioural problems, according to
authoritative research.
A giant study, which surveyed more than 13,000
children, found that using the handsets just two or three times a day
was enough to raise the risk of their babies developing hyperactivity
and difficulties with conduct, emotions and relationships by the time
they reached school age. And it adds that the likelihood is even greater
if the children themselves used the phones before the age of seven.
The results of the study, the first of its kind, have
taken the top scientists who conducted it by surprise. But they follow
warnings against both pregnant women and children using mobiles by the
official Russian radiation watchdog body, which believes that the peril
they pose "is not much lower than the risk to children's health from
tobacco or alcohol".
The research – at the universities of California,
Los Angeles (UCLA) and Aarhus, Denmark – is to be published in the July
issue of the journal Epidemiology and will carry particular weight
because one of its authors has been sceptical that mobile phones pose a
risk to health.
UCLA's Professor Leeka Kheifets –
who serves on a key committee of the International Commission on
Non-Ionizing Radiation Protection, the body that sets the guidelines for
exposure to mobile phones – wrote three and a half years ago that the
results of studies on people who used them "to date give no consistent
evidence of a causal relationship between exposure to radiofrequency
fields and any adverse health effect".
The
scientists questioned the mothers of 13,159 children born in Denmark in
the late 1990s about their use of the phones in pregnancy, and their
children's use of them and behaviour up to the age of seven. As they
gave birth before mobiles became universal, about half of the mothers
had used them infrequently or not at all, enabling comparisons to be
made.
They found that mothers who did use the
handsets were 54 per cent more likely to have children with behavioural
problems and that the likelihood increased with the amount of potential
exposure to the radiation. And when the children also later used the
phones they were, overall, 80 per cent more likely to suffer from
difficulties with behaviour. They were 25 per cent more at risk from
emotional problems, 34 per cent more likely to suffer from difficulties
relating to their peers, 35 per cent more likely to be hyperactive, and
49 per cent more prone to problems with conduct.
The
scientists say that the results were "unexpected", and that they knew
of no biological mechanisms that could cause them. But when they tried
to explain them by accounting for other possible causes – such as
smoking during pregnancy, family psychiatric history or socio-economic
status – they found that, far from disappearing, the association with
mobile phone use got even stronger.
They add
that there might be other possible explanations that they did not
examine – such as that mothers who used the phones frequently might pay
less attention to their children – and stress that the results "should
be interpreted with caution" and checked by further studies. But they
conclude that "if they are real they would have major public health
implications".
Professor Sam Milham, of the
blue-chip Mount Sinai School of Medicine in New York, and the University
of Washington School of Public Health – one of the pioneers of research
in the field – said last week that he had no doubt that the results
were real. He pointed out that recent Canadian research on pregnant rats
exposed to similar radiation had found structural changes in their
offspring's brains.
The Russian National
Committee on Non-Ionizing Radiation Protection says that use of the
phones by both pregnant women and children should be "limited". It
concludes that children who talk on the handsets are likely to suffer
from "disruption of memory, decline of attention, diminishing learning
and cognitive abilities, increased irritability" in the short term, and
that longer-term hazards include "depressive syndrome" and "degeneration
of the nervous structures of the brain".