There is little doubt that diesel exhaust particles (DEP) are carcinogenic. Searching the Medline Database (access free via, believe it or not, the Grateful Med) will yield the information.
Some extracts below:
"Epidemiologic data suggest that an increased risk of lung cancer for diesel exhaust exposed workers may be comparable with that for environmental tobacco smoke. Monitoring and control of the particulate is necessary. Prudent policy dictates continued efforts to reduce emissions of soot from diesel engines and decrease occupational exposure as a matter of good health and safety practice. Improvements in engine design, soot filters, and fuel modification will provide the best approach to exposure control. Further research is also needed in the areas of carcinogenic mechanisms and development and validation of biomarkers of exposure before reliable estimates of risk of human health effects in the occupational setting can be made."
"Ten studies considered diesel exhaust exposure based on a job exposure matrix or a similar approach; the summary RR for these studies was 1.13 (95% CI = 1.00-1.27). A positive dose-response relation was suggested by 10 of the 12 studies that provided relevant information. The summary RR for high diesel exposure was 1.44 (95% CI = 1.18-1.76). There was some evidence of publication bias, however, with a lack of small studies with null or negative results. Our review suggests that exposure to diesel exhaust may increase the occurrence of bladder cancer"
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Tim,
I know you're making a serious point as a medical man but I think the fact that we're all living longer despite all these "new" threats puts it into perspective.
Seriously I would like to know how the soot particles disperse in the environment. Perhaps they drop out of the atmosphere quite quickly with far less of a problem out here in the country. But if I'm mowing the roadside verge outside the house, as I do each week, am I stirring up these deposits with potential harm as I breath them?
David
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Whenever I see "research" that suggests something or other causes cancer, my eyes roll up to heaven. Example: In 1950 two thirds of the population smoked, 1 in 12 people were said to get cancer. Today, one third of the population smokes, we are told we have a one in three chance of getting cancer. In Asia 90% of all adults smoke, cancer cases are one third of our own.
I'm with David here, we keep reading about all these threats to our existance and our life expectancy gets longer all the time.
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You are right. Did you know that, according to staff at the Buildings Research Establishment, indoor air can be 10 times more polluted than outside?
What products of combustion do these folks think comes out of their gas central heating flue. Methane, carbon monoxide, nitrous oxide etc.
Its car free day tomorrow. When they shut down their cookers and heating, I'll park my car. Not.
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Just to add my tuppeneth worth.
It is true that PM10 (tiny particles) can cause an increase in the occurance of lung disorders (not just cancer). As DW rightly pointed out, we are living longer, and that is the main reason for more people catching cancer. Medical treatments and better diet is resulting in less and less death from malnutrition, and all other poverty related deaths.
60 - 70 years ago people died from currently preventable diseases, this is not the case nowadays.
People must die from something, and it just happens that as the cells in your body get older and the body cannot replace them as fast, there is an increased chance of some sort of mutation.
There are many sources of harmful materials that you are exposed to just be being alive. For example, have you ever had a new carpet laid? There are more harmful chemicals that will disperse in your house than you will be exposed to from a car's exhaust while walking down the road. Passive smoking is another recognsed source, but you can get more Carbon Monoxide from a badly maintained boiler than you will from active smoking.
It is a fact, that being alive is a risky affair, you cannot eliminate all sources of harm, you just have to minimise the risk to a perceivable acceptable level. This includes things like legislating car emissions, which will help to improve the overall environment and the quality of life.
Regards
Jonathan
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Tim,
I guess this thread is a follow up to the comments in David Woollard's diesel fuel of the future thread, if not then sorry got the wrong end of the stick. ..... Who said as usual.... really!
I was not saying that diesel particulates are not carcinogenic, you are quite right that there are studies which show an increased risk. What I object to is the way that diesel engines are bandied around as being the *only* producer of such particles.
Does the medical evidence have any studies on particulates from petrol engines? I would put a pound or two on there being none. The point being that it is only recently that people have realised that petrol engines *also* produce particulates, its just that they are small and not visible to the naked eye, therefore previously nobody looked for them.
Regards
Stuart
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Excuse me for being a little biased to diesel, and a bit thick when it comes to technical things but.......
Aren't diesels less poluting than petrols ? Ok, diesels emit more smoke than petrols, but they create less harmful emissions so are therefore less harmful to the ozone layer. They are also more fuel efficient and last last a lot longer than their petrol cousins. A diesel engine will outlast it's host, can't say that with a petrol engine, can you ?
Rgds,
Ash. ( diesel convert for the last 4 yrs )
p.s Alvin, where are you when we need you ?
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Quick poll
Preferred vehicle to follow on daily commuter run to work?
Post 92 cat fitted petrol engine vehicle?
Any bloody diesel?
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Car free day? Time to fire up my V8 Land Rover.....
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I often find myself behind fairly new diesel hatchbacks that emit clouds of smelly black smoke whenever the driver gets his foot down. Is this the particulate-rich output? If it is, it is a damn site worse than a petrol engine. Environmentalists moan about the CO2 output of petrol cars, which may or may not have harmful effects on our climate (I don't believe it) but the *local air quality* seems to suffer badly from diesels.
Buses and black cabs are the worst, by a large margin - but this government seems interested only in stopping us using our cars.
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I lived in a (student) flat on a 24 hour route to a distribution warehouse, on a hill. You got used to the noise, but you wouldn't believe the amount a black soot that used to accumulate on the window sill if you left a window open. That's, presumably, what is floating in the air for one and all to breathe. Scary!
Ash.
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Ash,
Picking up on your comment about soot fallout in a particular location you assumed it was from the immediate vicinity.
Isn't it also true that pollution moves with the weather patterns, so that most town pollution is shifted with the prevailing wind to drop out perhaps 10/20/30 miles away.
If you live this sort of distance north east of a major city, in an idyllic country location, the reality is you are breathing their second hand rubbish. Ever wiped the washing line before hanging out clothes??
That's it for a few hours, major service on a monster machine to do......Fiat Panda 750!
David
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If we made a fair comparison between petrol and diesel as to which is the least demanding on the environment we would have to take into account a very large number of factors into account to arrive at the truth.
In my biased opinion here is just a few.
Less manufacturing (which equates to fuel (and transport) of some description) because we don't need spark plugs, HT leads, distributors, more complex catalysers, longer lasting exhaust systems, and engines and so on.
The amount of fossil being used due to diesels using less.
the amount of fuel used in having to transport less.
Probably less refining required although that is only guesswork.
I imagine the list could go on indefinitely which must surely prove that diesel is far superior to petrol in its friendliness to the environment.
Perhaps someone out there would give a counter argument giving any areas where petrol is kinder to our planet.
I don't think it can on the grounds of emissions because the jury is still out on this one and I get a contrary opinion whenever I read a new survey.
Alvin
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The thing about visible diesel particulates is that most of them are caught by your body's filtering systems. You can even cough them out if you've accidentally stuck your head under a bus exhaust pipe. Petrol engine particulates (the invisible ones) are too small for the body's filters and too small to trigger a cough response. Just because you can't see them, doesn't mean they aren't coming to get you.
And another thing: diesel soot falls to the ground, invisible gases (including benzine - one of the most dangerous carcinogens on earth - from petrol engines) hangs around in the air, and drifts miles across the countryside. Stand a few miles downwind of a motorway and you'll see what I mean.
Chris
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Thanks Chris!
That's exactly what I have been saying for ages!
David
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I thought modern thinking was that all engines produce PM10,5,1 particulates, albeit in differing quantities.
I think I once read somewhere that an average tank of gas contains (used to contain?) over a pint of benzene, that was the reason behind those extractor nozzles that were introduced, in the US and Germany I think. They never made it here, presumably because they thought they couldn't get away with adding more to the price of the juice to pay for them.
Talking of wind borne particles, I remember my car getting coated in red sand that came all the way from the Sahara back in the 80's. I wonder whether that means there are tents somewhere in the desert covered in our diesel soot?
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Chris
You have a good point there.
Larger particles get filtered out by your nose.
Slightly smaller particles get caught by the walls of your throat and upper respiratory tract.
The little ones get down to your lungs.
The very little ones pass from your lungs into the bloodstream.
Regards
Brian
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I remember an article from many years ago about those cyclists in london that would wear a face mask whilst cycling.
The upshot of the article was that those particles that are large enough to be caught by such a filter are large enough for your lungs cleaning mechanism to deal with anyway.
Those particles which are small enough to cause problems for your lungs are also small enough to get through the filter.
The exception to this is if you are a regular smoker which kills off the cleaning mechanism in you lungs. So that everything just builds up in there.
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Some interesting responses which I cannot leave unchallenged:
1. The Grim Reaper will always get you eventually but there is no need to make it easy for him. A good transport system is essential for our economy and standard of living; road accidents and pollution are the price we pay; increased knowledge and it's application has and will lead to improvement. Cigarette smoking and other harmful lifestyle behaviours are clearly not essential and deprive large numbers of people not only the plesures of a healthy life but their spouses and loved ones of their company and support.
2. THe incidence of lung cancer in the "Third World" countries is low becuse the population has simply not smoked for long enough, however the incidence is rapidly rising.
3. There is often a trade-off. Soot particles at ground level are bad for lungs and buildings (and washing) but good in the high atmosphere because they reduce global warming. Similarly for Ozone which in the stratosphere reduces UV light and is good (this is a separate issue from global warning) but is a serious pollutant at ground level.
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