http://www.theaustralian.news.com.au/common/story_page/0,5744,17357035%255E23289,00.html
Why chronic noise gets taken to heart
Adam Cresswell, Health editor
November 25, 2005
LIVING with chronic noise doesn't just stress you out, it can also do
you in - by raising your risk of having a heart attack.
New research has found general environmental noise, such as the roar of
city traffic, increases the risk of heart attack by almost 50 per cent
for men and 200 per cent for women.
Noisy workplaces are another health danger, increasing the risk of
heart attack by almost a third for men, although not forwomen.
The researchers, who studied 4115 patients in Berlin's 32 hospitals
between 1998 and 2001, said the findings showed the need for tougher
regulations against workplace noise .
They called for ear protection to be compulsory in workplaces where
noise levels exceed 65 to 75 decibels. The noise level in a busy large
office is typically about 60 decibels.
Stefan Willich, lead author of the study, published yesterday by the
European Heart Journal, said the findings showed exposure to chronic
noise was associated with a mild to moderately increased risk of heart
attack.
"The increase appears more closely associated with actual sound levels
rather than with subjective annoyance," Dr Willich said.
"However, there were differences between men and women, and these need
further investigation."
Dr Willich and his team from Berlin's Charite University Medical Centre
compared more than 2000 heart attack patients with more than 2000
control patients, and used interviews and independent measurements of
noise levels in the patients' environments and workplaces.
The researchers found the risk of heart attack increased in line with
the rising noise levels, up to about 60 decibels. "We seem to be
looking at a threshold at which risk occurs and remains constant above
this," Dr Willich said.
One explanation was that noise might increase psychological stress and
anger, causing physical changes such as increased levels of adrenaline
and noradrenaline, hormones linked to increased blood pressure.
Garry Jennings, director of the Baker Heart Research Institute in
Melbourne, said the study was "enormously important from an
occupational health and potentially a worker's compensation point of
view". But Professor Jennings said many people in noisy environments
were factory workers, who were often from lower socio-economic groups
with higher rates of smoking and other behaviours that raised
cardiovascular risk.
"It's been difficult to find what the independent effect of the noise
is," he said.
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Boy, these guys are sharp. As far back as the 1400's, it was known that
a scurvy victim could be killed by a sudden loud noise.
TC