WHO Says Diesel Fumes Pose Significant Cancer Risk

Recently, the World Health Organization’s International Agency for Research on Cancer (IARC) concluded, after eight days of deliberating, that diesel exhaust ranks as a Class 1 carcinogen. In other words it’s been lumped in the same category as the likes of asbestos and mustard gas and considered a significant cancer risk.

The IARC arrived at that conclusion by using data from studies of workers that operated in close proximity to diesel exhaust, particularly a larger cohort study released back in March, that highlighted the prolonged exposure of diesel exhaust to 12,315 miners working in the U.S.

However, critics of the findings quite rightly point out that much of the data used was out of date and not reflective of the general population. The National Cancer Institute in the U.S., said research from “heavy exposure” to diesel exhaust in confined areas such as underground mining “cannot estimate with certainty the risks from diesel exposure for very low levels of pollution in the general environment.”

Additionally, Allen Schaeffer, executive director for the Diesel Technology Forum, says the WHO studies were based on diesel-powered equipment manufactured before the EPA began aggressively mandating reductions in diesel exhaust emissions in 2002.

“In the U.S., emissions from heavy-duty diesel trucks and buses have been reduced by 99 percent for nitrogen oxides and 98 percent for particulate emissions,” he said. In the U.S., the EPA indicates that diesel accounts for less than 6 percent of all particulate matter in the air.”
Even the EPA itself officially claims a 90 percent reduction in diesel exhaust emissions over the last decade, not only from cars, buses and trucks (like the Western Star dumper) seen here but also from other motorized vehicles such as ships and locomotives.

So, given this on balance, plus the fact that even the WHO admits modern formulation processes and emissions controls have “reduced the amount of particulates and chemicals” and the WHO has further said “it is not yet clear how the quantitative and qualitative changes may translate into altered health effects,” it essentially makes one ponder why the WHO would issue such a sweeping statement against diesel in the first place.

What do you think?


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  • jakattk

    How can WHO make such a wide spear statement that seem to be all speculation on their part?

  • Van

    Being an old geezer, I remember when filtered cigarettes were claimed to be less of a health risk. The were lower in tar, etc.

    So the question is not, how much lower are the emissions from diesels, 99% or whatever, the question is are the current levels of emissions a health risk. Certainly the earlier emission levels were hazardous.

    Next, when dealing with unknowns, we want to error on the safe side. So lets mandate all school buses must be hybrids that do not idle while parked near schools or parks or other places of high people density.

    I think the LA port authority decision to mandate hybrids is spot on, as I look at the sunset through a brown haze.

  • Marco

    That diesel emmissions have some negative effects on health is known from some years.

    The significance is that the OMS has formally include diesel emmissions in the list. Everybody may argue that some types of diesel pollute less than others, but that is compatible with the OMS results.

    The risk of the diesel emission is there, its up to the governants now to evaluate how they will decide the laws.

    Either way I prefer the safe side.

  • James Davis

    How can Allen Schaeffer, executive director for the Diesel Technology Forum, make such a wide spear statement that seem to be all speculation on his part?

  • James Davis

    How come you didn’t mention, like the original report from the New York Times did – http://www.scientificamerican.com/article.cfm?id=diesel-exhaust-fumes-can-cause-canc – that the particulates, even in clean diesel, causes bladder cancer and severe respiratory problems in children? And that the Diesel Technology Forum, has for decades fooled low intelligent truck drivers in believing that they took steps to keep the most dangerous parts of diesel out of their breathing space? Fossil fuel of all kinds are dangerous to our environment and human health and should be eliminated from burning to produce power for transportation or power for our homes and businesses. Don’t fool yourselves, diesel is dangerous no matter form you use it in or how many filters you put on it.

  • Anonymous

    Steve Hansen: You are absolutely right. The asbestos metaphore is misleading because diesel fumes caused several order of magnitude more deaths and other health problems than asbestos. So diesel is much more toxic than asbestos.

  • Steve Hansen

    Two noted UK medical and cancer reserach agencies have addressed misconceptions about the IARC finding. Here are their explanations:

    1) This is from an article in Cancer Research UK, the largest cancer research charity in the world (June 14, 2012). This includes an interview with Professor David Phillips – a Cancer Research UK-funded carcinogen expert from King’s College London:

    Just because something is in IARC’s top level category, it doesn’t necessarily mean it’s public health enemy number one – it’s more complex than that. As Professor Phillips explains, “IARC does ‘hazard identification’, not ‘risk assessment’.

    “That sounds quite technical, but what it means is that IARC isn’t in the business of telling us how potent something is in causing cancer – only whether it does so or not”, he says.

    To take an analogy, think of banana skins. They definitely can cause accidents – but in practice this doesn’t happen very often (unless you work in a banana factory). And the sort of harm you can come to from slipping on a banana skin isn’t generally as severe as, say, being in a car accident.

    But under a hazard identification system like IARC’s, ‘banana skins’ and ‘cars’ would come under the same category – they both definitely do cause accidents.

    “So, going back to diesel fumes – yes they’re in the same IARC category as, for example, mustard gas and asbestos. But saying diesel fumes are ‘as bad’ as asbestos is not what IARC categories are about,” says Phillips.

    2) This is from an article by the NHS-United Kingdom (June 14, 2012):

    The Daily Mail reports a World Health Organization (WHO) warning that diesel exhaust fumes are a “major cancer risk” and belong in the “same deadly category as asbestos, arsenic and mustard gas”. Meanwhile the BBC says that diesel fumes are “definitely a cause of lung cancer” …

    "While diesel fumes are now officially carcinogenic, the alarmist tone of the Daily Mail’s headline should be viewed with caution because the ‘deadly category’ of substances the Mail describes also includes sunlight and wood dust."

    Steve Hansen
    Diesel Technology Forum