Air Pollution May Damage Brain, Heart

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Air Pollution May Damage Brain, Heart

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WEDNESDAY, April 16 (HealthScoutNews) -- Air pollution may cause

brain damage similar to Alzheimer's disease, as well as heart

problems, two new studies suggest.

Dogs exposed to air pollution were found to develop damaged brain

cell genes in as little as four weeks, according to research

presented April 15 at the Experimental Biology 2003 conference in San

Diego.

The animals were exposed to the highly polluted air in different

parts of Mexico City, and compared against a control group of dogs

kept in less-polluted rural parts of Mexico. Mexico City is

considered one of the worst cities in the world for air pollution.

More than 200 dogs were involved in the study, which lasted for more

than a year. The dogs in the highly polluted environment suffered

lung and upper respiratory damage, which let particles enter the

central nervous system, leading to gene and DNA damage in their brain

cells. Even dogs less than 1 year old were found to have brain

lesions similar to those of human Alzheimer's patients, the

researchers say.

Lead researcher Dr. Lilian Calderon-Garciduenas, of the University of

North Carolina, says exposure to air pollution causes inflammation in

the respiratory tract, which lets tiny airborne particles and metals

enter the central nervous system and brain. This, in turn, causes

oxidative damage and DNA changes in brain cells.

Air pollution breaks down the vital blood-brain barrier that usually

keeps toxic substances away from the brain, she says.

" This is extremely important, " says Calderon-Garciduenas, " because

once you break down the barriers, you have an entrance for pollutants

directly to your brain. "

The researchers also found signs of lung damage in children as young

as 4 years old who were raised in Mexico City.

" The same breakdown in the respiratory system we're seeing in dogs is

happening in children and adults in Mexico City, " Calderon-

Garciduenas contends, " and it probably also happens in cities like

Los Angeles. "

A separate study presented at the same symposium found a link between

air pollution and heart problems in humans.

Exposure to air pollution raised levels of certain peptides in the

bloodstream that can constrict blood vessels and decrease blood flow

to the heart muscle, the researchers found.

The study was conducted at the Gage Institute of the University of

Toronto, where healthy volunteers were exposed to air pollution in a

laboratory setting. The volunteers were subjected to air pollution

about two to three times the level normally found in Toronto, which

is considered one of North America's less-polluted major cities.

The study focused on endothelin, a naturally occurring peptide that

plays an important role in blood vessel health.

" If we expose healthy humans to airborne particulates, we can

document a doubling of endothelin in the blood, " says Renaud ,

one of the researchers and head of Health Canada's Inhalation

Toxicology and Aerobiology Section.

" We now have at least one mechanism that could plausibly explain how

someone with a heart condition exposed to a low level of air

pollution could die or come down with severe symptoms, such as

congestive heart failure, " says.

Recent epidemiological studies have found higher rates of death and

hospitalization in cities with high levels of air pollution.

says the culprit appears to be airborne particulates.

When test subjects breathed polluted air for as little as two hours,

the level of vasoconstrictive peptides in their blood rose sharply

and stayed at abnormally high levels for as long as 24 hours, even

without further exposure. The changes in peptide levels were

proportionate to the concentration of particles to which the subjects

were exposed.

" The picture is starting to come together of why we see these spikes

in mortality associated with air pollution levels, " says Fred ,

a researcher with CIIT Centers for Health Research, an independent,

non-profit research organization based in North Carolina's Research

Triangle Park.

" The mortality may be coming about because you have this exposure,

and how well can your system handle this added stressor? " he says.

Elevated levels of endothelin can reduce blood flow by as much as 50

percent, particularly in people with atherosclerosis, high blood

pressure and diabetes, says.

Further study needs to be done on which specific particulates and

their components produce the rise in vasoconstrictive peptide levels,

he says.