Short-Term Exposure To Diesel Fumes Causes Changes In Gene Expression

BarbaraHudson writes: The Vancouver Sun is reporting on experiments using human volunteers showing that just two hours of exposure to diesel exhaust fumes led to biological changes; some genes were switched on while others turned off. The air quality during the diesel fume exposures is said to be comparable to a Beijing highway or shipping ports in British Columbia. The next step is for researchers to study how changes in gene expression from air pollution affect the human body over the long term, since the study shows genes may be vulnerable to pollution without producing any obvious or immediate symptoms of ill health."

Comments

Re:No control experiment

[BarbaraHudson]

Maybe you should consider that asthma is on the rise, and that people with asthma are like the "canary in the mine shaft".

It showed that just two hours of exposure to diesel exhaust fumes led to biological changes that meant some genes were switched on while others turned off.

So, how much exposure before it happens to the rest of us? What can we do to lessen the effects? There are relevant questions.

Re:No control experiment

[X0563511]

Rather I think the important bit here is the revelation that common air pollutants affect gene expression, not the effects of such expression. The mechanism is the important part.

I assume they had a control group... is that a correct assumption?

Re:No control experiment

[BarbaraHudson]

They had the subjects randomly exposed for 2 hours of filtered air or two hours of air contaminated by diesel fumes. Changes only happened when the subjects were exposed to diesel fumes. So basically, they controlled for everything except the fumes.

Re:No control experiment

[MightyMartian]

Why should making a specific industry stop causing us harm require the industry find profit in it? Shouldn't it be enough to demonstrate the harm and industry then stop the harm? Frankly if an industry requires a profit motive to stop hurting us, then that industry needs serious reforms at a root level.

Well duh!

[smooth wombat]

Hopefully all those morons who are ""rollin coal" will be sterile so they can't pass on their defective genes to another generation.

Why diesel fuel?

[drinkypoo]

âoeDiesel engine exhaust is a known carcinogen that is responsible for two-thirds of the lifetime cancer risk from air pollution in our region,â Moore said. âoeThe prohibitions that come into effect in 2015 are essential to protect human health by reducing emissions of harmful diesel soot from industrial and construction machines.â

Why is this witch-hunt against diesel fuel? Why not gasoline? Can someone explain to me why the world is up in arms about diesel fuel but calmly ignoring the fact that gasoline engines produce just as much soot, but with finer (and thus more hazardous) particulates? And that they release more unburned hydrocarbons into the atmosphere, although to be fair, direct gasoline injection is erasing that particular problem. Is this just about preventing us from using biofuels?

Re:Why diesel fuel?

[caseih]

But gasoline doesn't produce the same soot. Plainly put, diesel particulates are more toxic than particulates from gasoline combustion. Modern diesels, however, are much, much more clean than older diesels. I drove a diesel rental car in Turkey recently that was diesel and its exhaust just smelled like steam.

Diesel engines have two problems when it comes to pollution. Particulates and NOx emissions. Particulates can be eliminated with by increasing the heat and pressure of combustion. That takes care of most immediate, toxic product of combustion right there. However, increasing heat and pressure also leads to more N2 reacting with O2 to make NOx, which causes smog and acid rain, also serious human health concerns. If you go the other way and cool combustion way down, you can virtually eliminate NOx, but you get tons of particulates. So either reduce NOx by cooling combustion with recirculated exhaust gasses and stick on a filter to catch and burn particulates (the dreaded regen cycle that truckers can tell you about), or turn up the heat and treat NOx separately using a catalyst, urea. Most auto makers are finding that urea into the exhaust works best because the engine can be super simple again. However the big problem with this is that in northern climates (most of the western world), cars don't drive far enough to warm up completely, so you still have unwanted pollution.

Gasoline (petrol) does emit some particulates but they seem to not be as dangerous. Petrol engines also emit NOx but modern catalytic converters convert it to N2 and water.

And of course all fossil fuels emit net CO2. Biofuels can theoretically be carbon neutral, but if they are diesel-like (burn in a diesel engine) they still very much have the same pollution issues as diesel, and will have to be treated in the exact same way, using EGR, SCR (with urea), or some other technology. Likewise gasoline-like biofuels will still have to have the same pollution control systems as regular gasoline engines.

We already know something about long-term exposure

[PapayaSF]

We already know something about long-term exposure, based on observing career truck drivers: diesel fumes don't cause weight loss.

Ultrafine particles

[Anonymous Coward]

Ultrafine particles (UFP) are probably both the least well-studied and least regulated form of air pollution (IIRC, they're somewhat tricky to reliably measure at all in an uncontrolled environment, let alone measured by a means that can be deployed for routine large-scale monitoring), and there's a small pile of studies showing that they do have health effects, though no one seems to know exactly what the mechanisms or dose-response curves are, or how the short-term effects translate into identifiable disease etiologies. For example, there are studies in both rats[0] and humans[1] consistent with the presence of UFP inhibiting the exercise-stimulated production of brain-derived neurotrophic factor (BDNF), a neurological growth factor that is believed to play a key role in multiple psychiatric disorders and even some forms of obesity. There are other studies showing other effects; those were just the ones that particularly came to mind.

I bring this up because although modern diesel engines are far cleaner than the classic models, they are known to produce considerable amounts of UFP pollution. Gasoline engines and various other technologies (laser printers / photocopiers, various forms of precision machining...) aren't entirely innocent, either.

[0] http://www.ncbi.nlm.nih.gov/pubmed/22867973
[1] http://www.ncbi.nlm.nih.gov/pubmed/21708224

Re:No control experiment

[drinkypoo]

Maybe you should consider that asthma is on the rise, and that people with asthma are like the "canary in the mine shaft".

I own both [old school indirect-injected, pollution control-free] diesels and [modern, multiple heated O2 sensor] gasoline vehicles, and I also have activity-induced bronchial asthma which can also be set off by allergies, like my allergies to dogs and cats. And what I've noticed is that gasoline fumes are probably an order of magnitude more likely to kick off my asthma. Which is why I'm wondering why they're studying this with regards to diesel fumes. I want to know who's footing the bill for this bull. It's not that it's bad science, it's that the motivations are probably evil if they're not looking at gasoline, which any asshole who's been to a filling station more than twice can tell you is more volatile than diesel. Diesel clings to your hands, but you can feel gasoline in your brain.