Nano-sized Ultrafine Particles May Be Most Damaging Component of Air Pollution for Heart Disease

Green Car Congress ^ | Jan. 18, 2008 | Staff

[T Ruth]

A new study indicates that ultrafine particles—particles of less than 0.18 micrometers—from vehicle emissions may be the most damaging components of air pollution in triggering plaque buildup in the arteries, which can lead to heart attack and stroke. The findings appear in an open access article in the 17 January online edition of the journal Circulation Research.

A team from University of California, Los Angeles (UCLA); the University of Southern California; the University of California, Irvine; and Michigan State University contributed to the research, which was led by Dr. Andre Nel, UCLA’s chief of nanomedicine. The study was primarily funded by the National Institute of Environmental Health Sciences and the US Environmental Protection Agency (EPA).

It appears that the smallest air pollutant particles, which are the most abundant in an urban environment, are the most toxic. This is the first study that demonstrates the ability of nano-sized air pollutants to promote atherosclerosis in an animal model.

—Dr. Jesus Araujo, first author and assistant professor of medicine and director of environmental cardiology at the David Geffen School of Medicine at UCLA

The EPA currently regulates fine particles at 2.5 micrometers, but doesn’t monitor particles in the nano- or ultrafine range. These particles are too small to capture in a filter, so new technology must be developed to track their contribution to adverse health effects.

We hope our findings offer insight into the impact of nano-sized air pollutant particles and help explore ways for stricter air quality regulatory guidelines.

—Andre Nel

The UCLA research team previously reported that diesel exhaust particles interact with artery-clogging fats in low-density lipoprotein (LDL) cholesterol to activate genes that cause the blood-vessel inflammation that can lead to heart disease. (Earlier post.)

In the current study, researchers exposed mice with high cholesterol to one of two sizes of air pollutant particles from downtown Los Angeles freeway emissions and compared them with mice that received filtered air that contained very few particles.

The study, conducted over a five-week period, required a complex exposure design that was developed by teams led by Dr. Michael Kleinman, professor of community and environmental medicine at UC Irvine, and Dr. Constantinos Sioutas, professor of civil and environmental engineering at USC.

Researchers found that mice exposed to ultrafine particles exhibited 55% greater atherosclerotic-plaque development than animals breathing filtered air and 25% greater plaque development than mice exposed to fine-sized particles.

Pollutant particles are coated in chemicals sensitive to free radicals, which cause the cell and tissue oxidation. Oxidation leads to the inflammation that causes clogged arteries. Samples from polluted air revealed that ultrafine particles have a larger concentration of these chemicals and a larger surface area where these chemicals thrive, compared with larger particles, Sioutas noted.

Ultrafine particles may deliver a much higher effective dose of injurious components, compared with larger pollutant particles.

—Andre Nel

Scientists also identified a key mechanism behind how these air pollutants are able to affect the atherosclerotic process. Using a test developed by Dr. Mohamad Navab, study co-author and a UCLA professor of medicine, researchers found that exposure to air pollutant particles significantly decreased the anti-inflammatory protective properties of HDL cholesterol.

To explore if air particle exposure caused oxidative stress throughout the body—which is an early process triggering the inflammation that causes clogged arteries—researchers checked for an increase in genes that would have been activated to combat this inflammatory progression.

They found greater levels of gene activation in mice exposed to ultrafine particles, compared to the other groups. The next step will be to develop a biomarker that could enable physicians to assess the degree of cardiovascular damage caused by air pollutants or measure the level of risk encountered by an exposed person.

Previous studies assessing the cardiovascular impact of air pollution have taken place over longer periods of exposure time, such as five to six months. The current study demonstrated that ill effects can occur more quickly, in just five weeks.

The research team included investigators from the fields of nanomedicine, cardiology and genetics. Additional co-authors included Berenice Barajas, Xuping Wang, Brian J. Bennett and Ke Wei Gong of the David Geffen School of Medicine at UCLA, and Jack Harkema from the department of pathobiology and diagnostic investigation at Michigan State University.

Additional grant support was provided by the National Institute of Allergy and Infectious Diseases; the National Heart, Lung and Blood Institute; and the Robert Wood Johnson Foundation.

[T Ruth]

It is worthwhile following the link to the article to read the comments. (The title of the article was shortened to meet posting requirements.}

[rfp1234]

Oops - so will NYC reverse the ban on trans-fats now?

[GOP Poet]

bookmark

[bcsco]

Color me skeptical. Heart disease and arteriosclerosis have been around for ages. Long before the cumbustible engine. It well may be that these pollutants are contributive, but it reads like just another hit piece on society. As with global warming, I wonder at the motivation and how the tests were conducted.

Oh, and my credentials. I’ve had heart disease diagnosed since ‘85. I’ve had 4 angioplasties, a triple-bypass, a stroke, and my arteries (including my bypasses have re-closed). I live off my medication. I’ve not lived in an urban environment since I was pre-teen.

As I said, color me skeptical.

[Uncle Ike]

” Color me skeptical. “

While I don’t have your impressive - and terrible - credentials, I, also, am skeptical —

And that comes from looking at the ‘Source’ of this article..

“Green Car Congress”, indeed......

(Junk science in support of the political agenda du jour....)

[bcsco]

Junk science in support of the political agenda du jour....

That's how science operates today. It's all about grants.

[Retired Chemist]

What was the human life span before vehicles with internal combustion engines?

[Gorzaloon]

Long before the cumbustible engine. It well may be that these pollutants are contributive, but it reads like just another hit piece on society. As with global warming, I wonder at the motivation and how the tests were conducted.

We shall see if people in the new Industrial China suddenly develop symptoms as pollution worsens and worsens. For years we have heard about Asian diets and better cardiovascular health. We have a perfect petri dish for the experiment, involving a sample size of billions.

Of course, they have cadmium issues, so there is a flaw there already.

[Gorzaloon]

Intersetingly, I was just sent this the other week:

In 1907 life expectancy was 47. There were only 8,000 cars in the U.S. , and only 144 miles of paved roads.

Five leading causes of death in the U.S. Were:

1. Pneumonia and influenza

2. Tuberculosis

3. Diarrhea

4. Heart disease

5. Stroke

The absence of antibiotic use skews this, plus we liked to cook things in lard.

"Nano"anything=Funding.

But there could be a glimmer of truth in it. Consider various hydrocarbons and Bad Things like dibenzopyrenes adsorbed on a medium with gigantic surface area/volume ratios. It makes a pretty good delivery system for a drug or other compound.

[BuffaloJack]

Blah, blah, blah, blah, blah!
The whiners will always pick something to blame and make the rest of us suffer financially to fix their imaginary problem.

[hellbender]

A cardiologist recently told me that cardiovascular disease is largely due to life-style choices. Far more people get CV disease because they smoke, are obese, and don’t exercise, than from pollution.

[BuffaloJack]

> A cardiologist recently told me that cardiovascular disease is largely due to life-style choices. Far more people get CV disease because they smoke, are obese, and don’t exercise, than from pollution.
Smoking, obesity and other factors just do the setup. The chlamydia pneumonia germ then comes in and causes the lesions that actually create the plaques that are the cardio vascular problem.

[millerph]

What was the human life span before vehicles with internal combustion engines?

Much shorter, but that was before vaccines & antibiotics also.

Here’s a better question: is the rate of CVD 50% higher in Los Angeles than in small town America?

[pieceofthepuzzle]

Looked at the paper online. There are a lot of things it appears they didn’t control for, or analyze. For example, I didn’t see any data evaluating the stress responses in these mice. It’s possible that by exposing them to these nanoparticles they caused a stress response with increased blood pressure and/or higher levels of circulating steroids and catecholamines etc. It’s an interesting finding, but the paper is certainly not conclusive about mechanism, and the clinical implications of this are unclear, at best. Genetics and the standard parameters (blood pressure, cholesterol levels, activity, smoking, diabetes) are the biggest determinants of whether or not you will wind up with vascular or coronary disease.

[ottbmare]

I, also, am skeptical — And that comes from looking at the ‘Source’ of this article.. “Green Car Congress”, indeed...... (Junk science in support of the political agenda du jour....)

Just because idiots like the Green Car Congress report a piece of news, does not mean that the news they're reporting is factually wrong. This looks like good science, folks. And the National Institute for Allergy and Infectious Disease is not handing out grants to charlatans. These workers are very well-regarded in their research area. The work was carefully peer-reviewed. The cases of people with heart disease who don't live in the city, or healthy people who do, do not negate the findings presented here.

[spanalot]

To All:

Do you or someone close to you have heart disease with EITHER a preceding history of real bad teeth or ulcers.

Everyone I know fits this pattern.

[Right Wing Assault]

So, if you want a more more fuel efficient nano-particle generator, see this post from down the page:

http://www.freerepublic.com/focus/f-news/1956588/posts

[exDemMom]

I’m always suspicious of findings like this. Are car emissions *really* the only source of nanoparticles? It seems to me very odd and unlikely that the physical processes that could produce nanoparticles *only* exist in combustion engines.

[Cvengr]

The UCLA research team previously reported that diesel exhaust particles interact with artery-clogging fats in low-density lipoprotein (LDL) cholesterol to activate genes that cause the blood-vessel inflammation that can lead to heart disease.

Does this mean young adolescents might now be tempted to hang around truck stops, eating french fries as a legal substitute for Viagra?

[boop]

"A cardiologist recently told me that cardiovascular disease is largely due to life-style choices"

I can't believe they said that. Genes are the biggest factor. There are 10 year olds that have plaque in their arteries. Some families just have lots of "bad cholesterol" and they have less "good" cholesterol. Smoking and being 300lbs doesn't help, but even thin non-smokers get heart attacks.