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Chemical Component of Diesel PM Can Compromise Blood Flow

1 May 2007

A new study found that exposure to a chemical component of diesel exhaust particulate matter can compromise the ability of resistance arteries to regulate blood flow to bone marrow. Post-menopausal females, the elderly and males are most likely to be impacted, according to a new vascular biology study—using an animal model— presented at the 120th Annual Meeting of The American Physiological Society in Washington, DC.

Particulate matter from diesel exhaust can remain airborne for extended time periods, and travel long distances prior to being inhaled. When inhaled, chemical components such as polyaromatic hydrocarbons (PAH) attached to the particles can interact with the body. Quinones are PAHs and are among the more toxic components of diesel exhaust. In the current study, the investigators used phenanthraquinone (PQ) because previous research found PQ to compromise the ability of larger blood vessels to relax.

The principal nutrient artery (PNA) is the major resistance vessel that regulates blood blow to the femoral bone marrow. The ability of arteries to dilate (widen) declines with age and this corresponds with reduced blood flow in an artery’s target organ. Impaired blood flow regulation in the bone marrow can have wide- and long-reaching health consequences. It is unclear what PQ does to the ability of this artery to dilate, and how age or gender alters any such effect.

The research team sought to determine whether PQ impairs vasodilation in the PNA and identify whether age, gender or estrogen alters the presumed effects of PQ. The researchers isolated and cannulated femoral PNAs from intact and ovariectomized (OVX) female rats (6, 14 and 24 months) and male rats (6 and 24 months). To evaluate the ability of the PNA to dilate when it was incubated with PQ, researchers used the chemical acetylcholine (ACh). A series of ACh doses were administered over time, starting with low doses and graduating to higher doses to produce maximum dilation of the artery.

The researchers found that:

  • Exposure to PQ compromised by approximately 65% the ability of the blood vessels to effectively dilate in six month old male rats, but had no effect in female rats;

  • At 14 months (female rats) and 24 months (female and male rats), PQ had impaired and abolished vasodilatation, respectively;

  • In all OVX rats (i.e., the young females who had lost estrogen due to menopausal status), PQ abolished vasodilatation; and

  • Following the loss of estrogen, particularly at six months where a cardioprotective effect was previously observed, PQ exposure had obliterated vasodilation.

The researchers concluded that exposure to the diesel particle component PQ can compromise the ability of the PNA to regulate bone marrow blood flow in males, the elderly and post-menopausal females in an animal model. They suggested that these findings may provide an important link to other discoveries involving the protective effects of estrogen to environmental pollutants.

The study, “Effects of Age, Gender, and Estrogen on Endothelium-Dependent Vasodilation Subsequent to Phenanthraquinone Exposure”, was conducted by Rhonda D. Prisby, Judy Muller-Delp and Timothy R. Nurkiewicz, all of the Center for Interdisciplinary Research in Cardiovascular Sciences at the West Virginia University School of Medicine in Morgantown, WV, USA. The research was funded by the Health Effects Institute and the National Institutes of Health.

May 1, 2007 in Diesel, Emissions | Permalink | Comments (15) | TrackBack (0)

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Population study of urban areas in Europe and control for diet, exercise and heredity needs to be done next.

Now where are those who are crying about our emissions regulations? Whimpering about how the US is too hard on diesels and we should have had more dirty diesels years ago.

You're perfectly right, Patrick. Living in France, I can really tell that Diesel exhaust is a nightmare, especially when riding your bike in the city. Even with some new cars.

So don't get upset that we're not as efficient as cars are in Europe. We emit more CO2, but our anti-smog regs are the strictest in the world. It's a trade off: Air quality for fuel efficiency. The only way we can approach the overall efficiency of a diesel with gasoline are hybrids.

Does bio-diesel produce PQ?

"Diesel exhaust" is pretty vague. Ultra-low, High-sulpher, DPF, Cats, or not, BioD?...Give us some specifics plz.

Whimpering about how the US is too hard on diesels and we should have had more dirty diesels years ago.

The problem is that we weren't hard enough. If we'd taken out the sulfur when we stopped adding lead to gasoline we'd have mature emission treatment technology by now.

This study looked at PAHs in diesel PM. Of course, "gasoline exhaust is enriched in particulate PAH as compared with diesel exhaust" (PDF warning -- see pp 13-14. This despite the fact that the diesel emissions in the study are nearly all from heavy duty vehicles). OTOH, diesel fuel has higher levels of PAHs than gasoline (OT3H the vapor pressure of diesel is much lower). PAH emissions are not regulated by EPA so are not included in Tier/Bin ratings.

There is more of a problem with old diesel engines. I just had my 2005 VW Passat TDI emission tested here in Colorado. The requirement is to be have less than 35% opacity for cars and less than 40% for trucks (measure of how dense the particulates are). My VW was 3% at full throttle at 60mph and 1% at full throttle at 30mph. My car is way under the limit, so that's makes me think that the high limit is there for old diesel engines.

Why is it assumed that this study exonerates gasoline exhaust or any other combustion source for that matter?

This from an abstract from Environmental Chemistry:


"...Mean concentrations of individual target quinones ranged from 15–140 ng mg–1 in diesel and gasoline exhaust particles..." (emphasis added)

http://www.publish.csiro.au/paper/EN05089.htm


Quinones have been identified in cigarette smoke (Redox Potential and Quinone Content of Cigarette Smoke - http://pubs.acs.org/cgi-bin/abstract.cgi/ancham/1977/49/i13/f-pdf/f_ac50021a013.pdf?sessid=6006l3), and wood smoke (Health Effects of Wood Smoke - http://www.ecy.wa.gov/pubs/92046.pdf).

As cidi mentioned, gasoline PM typically has higher concentrations of PAH.

I agree that old high-emitting diesels may be problematic, but I fail to see how air quality in the U.S. will be adversely affected by increased market share of light-duty diesel vehicles equipped with modern after-treatment technology (e.g., DPF) that's been show to reduce TPM emissions at or below that of modern gasoline vehicles.

Does bio-diesel produce PQ?

Don't know about PQ specifically but PAHs in general are way down (PDF warning, see pp 9-14).

Petrodiesel is mostly alkanes with some aromatics. Aromatics improve lubricity but lower cetane and are also cheap filler cracked from heavier fuel fractions. (They're also high octane so aromatics are an important component of gasoline). Biodiesel, whether you're talking fatty acid ester or BTL, has no aromatics, so it's much more difficult to form PAHs (not coincidentally FAE and BTL have higher cetane than petro).

Neil:
Some pro-bioDiesel site says that B100 decreases PM by 47%, unburned hydrocarbons by 67% and PAH down by 75-85%. However that's not what we see most the time. With B20 PM is down only 12%, but I forget about the rest of the stats

The new "clean diesels" are precisely the only way they should be consumed. My remarks are geared towards those who wished we had "dirty diesels" over the long run rather than the new generation of diesels capable of meeting current emissions regulations.

Trust me, newish diesels still smoke like bandits.

I live in Europe so I experience them all the time.

In the UK its easy to see from a cars plates when it was made/registered.

I know for a fact that the EURO IV diesels still smoke when under load (ie. accelerating from stop lights)

The official emission tests for drive cycles don't load the engines heavily enough for the tests to see smoke emissions.

Only the new EURO V diesels are clean enough to drive behind without having the air vents on recirculate. They're not mandated until 2009 though, but some are already on sale. They're a massive improvement, but I'd say that Americans have been wise not to allow diesels in light passenger cars until Tier II bin 5.

From my experience of diesels that was a good call.

Andy

So, lets see: Gasoline produces health-harming smog; we have a Stanford professor that says alcohol is detrimental to the world's health and now we have a study that claims the same is true of diesel. And, they all produce excessive co2. It appears that we have a problem that threatens our way of life. There is no carbon fuel that is acceptable for use in internal combustion engines (ICEs). More and more is the case that ICEs are lousy forms of power because they are inefficient and simply run too damn dirty.

However, from a practical standpoint, we will be stuck with ICEs for a long time and the oil and auto companies will work to slow down any changes as long as possible. You see their profits are at stake and for a long time they have controlled the U.S. energy market. They will continue to exercise this control as long as they can. Thus you see the move to diesel and the oil companies moving to control the battery markets.

I believe the ultimate car will be some form of BEV and that much of the transportation problems for large cities will be solved by mass transit. The shame in all this is the little the government has done to move these relatively new markets in the past. I sincerely hope they wake up and start working with the people to create a universal model of U.S. future transportation that also addresses public health and not just industry profits.

One more reason to turn to progressively more electric dominant PHEVs, as soon as batteries become suitable and more or fless affordable.

Once PHEVs cover 100+ km on elctrical power, pollution created by the ICE driven on-board generator will become almost meaningless.

Could the new Firefly, lower cost, light weight, 'foam' lead battery, be use on first generation PHEVs to keep the price down?

There are developments in DME in China"
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