A new research by Johns Hopkins University suggests that an
earlier exposure to some pollutants can cause harm that shows up
only years later, according to media reports Monday.
Sharp cuts in environmental lead levels more than 20 years ago
didn't stop its widespread effects, said the researcher.
"We're trying to offer a caution that a portion of what has been
called normal aging might in fact be due to ubiquitous
environmental exposures like lead," said Dr. Brian Schwartz of
Johns Hopkins University.
Animal studies showed that infant mice exposed to chemicals took
on very subtle effects in young adulthood. But more dramatic harm
in areas like movement and learning appeared when they reached old
Researchers contributed this prolonged effect to the fact that
when some brain cells are destroyed in early life, the brain draws
on its reserve capacity until it loses more cells with aging hence
symptoms like forgetfulness or tremors appear.
Other pollutants like mercury and pesticides may do the same
thing, said Schwartz.
The long-delayed effects have also been found in tobacco and
asbestos which can lead to cancer.
(Agencies via Xinhua January 28, 2008)