Once again a group of health professionals gets the science wrong on diluted bitumen and the Trans Mountain Pipeline Expansion project

By now, my opinion of physicians and health care professionals wandering into the field of environmental policy are well known. As I have written previously:

While I trust MDs on matters relating to my health and wellness, I will stick with subject matter experts on topics that are not related to medicine.

Well another band of well-meaning, but ill-informed, health professionals are at it again. This time with a letter to the Prime Minister where they absolutely mangle the science behind the Trans Mountain Pipeline Expansion (TMX) project. While I could really go after their entire letter, I lack the time or the enthusiasm to do so. Therefore, this blog post will address the egregious errors from their sections on diluted bitumen. For simplicity here is the section of the letter I intend to debunk.

Specific to TMX, diluted bitumen is dangerous and considerably more toxic than crude oil. It behaves unpredictably in aquatic environments, sometimes floating, sometimes sinking. The marine spill scenario in the NEB review was very optimistic. It was set far away from any population center despite the clear hazards of a seven-fold increase in tankers through Vancouver’s busy harbour with three bridges and two dangerous narrows adjacent to downtown with over a million people, a population which includes Indigenous communities whose close connection to the land makes them particularly vulnerable to environmental contamination. We need to know the health impacts of a worst-case spill in the most populated area of the project, e.g. a large tanker spill, close to shore and under poor air quality and high temperature conditions prominent in the past several summers in British Columbia. We must additionally acknowledge that even best-case scenario clean-up of crude oil results in only 5-15% oil recovery, with spilled bitumen likely to have even lower levels of recovery.

Finally, the health impacts assessment did not adequately consider the extremely high risk from benzene, one of the most toxic components of the pipeline product diluted bitumen (dilbit). The increased risk of childhood leukemia was ignored by the review as was consideration of genetic and other special population vulnerabilities. 

Toxicity of Diluted Bitumen

The authors start the section by making a demonstrably false claim about the toxicity of diluted bitumen saying it is “considerably more toxic than crude oil”. They later take special notice of the benzene composition of diluted bitumen and the risk it poses to children and indigenous communities.

As most informed observers know, diluted bitumen, due to its chemical nature, is less toxic to humans than most refined fuels and most other crude oils. To explain, the most toxic components in petroleum hydrocarbon mixtures are their monoaromatic hydrocarbon constituents (like benzene, toluene, ethylbenzene and xylenes or BTEX). One of the features of bitumen is that, like other heavy oils, it has relatively low BTEX concentrations. Geochemically, bitumen is a type of crude oil where virtually all of the most toxic volatiles have been biodegraded in the subsurface. That is why the material is so viscous and why they have to add condensate to make it flow.

Relatively speaking diluted bitumen has some of the lowest BTEX concentrations of all crude oils. As detailed by in the US National Academies of Science (NAS) report on the subject:

The average BTEX in diluted bitumen at 0.89 % vol [reported in % by volume] was similar to the heavy crude oils at 0.84 % vol, whereas light and medium crude oils were 2.56 and 2.80 % vol respectively.

With special regard to benzene, both bitumen and condensate have some benzene (the five year average for benzene concentration in Cold Lake Blend is 0.23% +/- 0.03 %) but West Texas Intermediate crude has twice the benzene while low-benzene gasoline has almost 4 times as much.

What this means is that while diluted bitumen is toxic so are gasoline, aviation fuel, light crudes, medium crudes and West Texas Intermediate crude. All of which are substantially more toxic to humans than diluted bitumen. So when the ill-informed health professionals make the claim that diluted bitumen is “considerably more toxic than crude oil” they are absolutely and categorically wrong. Similarly, when they warn of the risks of benzene in diluted bitumen, they are once again barking up the wrong tree because any replacement for diluted bitumen will have considerably higher benzene concentrations than diluted bitumen and would thus pose a higher risk to human and ecological health.

Marine Risks

The topic of marine risks is also raised by the health professionals. I have written extensively on the topic of the marine risks of the TMX and my research shows that once again the their arguments are not consistent with the current research.

Their tired argument about “seven-fold increase in tankers through Vancouver’s busy harbour with three bridges and two dangerous narrows” completely ignores the added precautions associated with the TMX project. The NEB required a detailed risk analysis of the TMX. The critical document on this topic is the report Termpol 3.15 – General Risk Analysis and intended methods of reducing risk which evaluated the risks of the project. It concluded that “with effective implementation of risk reducing measures most of the incremental risk resulting from the project can be eliminated”.

To put a number on it:

  • Without the project the risk of a credible worst case oil spill is estimated in 1 in every 3093 years….If all the risk reducing measures discussed in this report are implemented the frequency will be one in every 2366 years.
  • This means that after the Project is implemented, provided all current and future proposed risk control measures are implemented, the increased risk of a credible worst case oil spill in the study area from the Trans Mountain tanker traffic will be only 30% higher than the risk of such an occurrence if the Project did not take place.

By increasing the number of tankers by 7 times, but also implementing the changes that were ultimately mandated by the NEB, the risk of a spill is less than one event every 2000 years. So no, the risk does not increase by 7 times, it increases by barely 30%. Moreover, remember that 30% is multiplied by a near-zero number. 30% more of near-zero remains almost-zero. Essentially, the experts have established that the project provides no significant increase in risk over those risks we accept every day.

In exchange for that negligible increase in risk we get economic prosperity and the economic health and goodwill of our neighbouring provinces. The dollars generated by this project are what pay for our health care system, which coincidentally pays all these physicians, nurses and health professionals.

Moreover, as I have noted previously, any cold-eyed analysis of the relative risks shows that the TMX reduces our regional risks of oil spills. Blocking the TMX will increase the likelihood of a disastrous rail spill that could spell the end of a major fishery or result in the deaths of dozens of innocents. It also increases the likelihood of a marine spill from a foreign-flagged tanker.

Spill Recovery

The authors also repeat that worn out quote about diluted bitumen spill recovery “even best-case scenario clean-up of crude oil results in only 5-15% oil recovery“. That factoid is, not surprisingly, based on an out-of-date study.

The federal government has spent millions of dollars researching the behaviour of diluted bitumen in an oil spill and has summarized the results at Transport Canada. The conclusion of the research is that diluted bitumen is somewhat easier to clean than heavy crude and can be much easier to clean than a light oil spill. As for that 5%-15% number the health professionals trot out. The 5% -15% number involves open ocean spills far away from spill response facilities not spills in a well-managed port. In the one example of a marine spill, in the Burrard Inlet, they were able to recover 95% of the spilled material.

Fisheries and Oceans Canada modeled an oil spill in the Salish Sea and concluded that the majority of the oil would stay on the surface rather than dispersing into the water column. That would mean that the floating oil would be recoverable using current spill response technologies. As for the sinking scenario, that scenario only applies in a tiny bit of the Salish Sea, in what is the widest sea lanes in the entire route.


So once again we have well-intentioned health practitioners demonstrating my father’s adage quite effectively: “never trust an MD on any topic that is not related to medicine”. In that short 214 word snippet from their letter we were able to find appeals to sentiment, wild exaggerations and outright errors. It simply amazes me how a bunch of Emergency Room Physicians, Family Doctors and other non-specialists can get so much air play on their ill-founded concerns and that no one else appears to call them on it when they do.



Here is a breakdown of the BTEX in every significant blend of Canadian diluted bitumen

BTEX dilbit

Source: Federal Government Technical Report: Properties, Composition and Marine Spill  Behaviour, Fate and Transport of Two Diluted Bitumen Products from the Canadian Oil Sands – ISBN 978-1-100-23004-7 Cat. No.: En84-96/2013E-PDF


As for crude oils – from Characteristics of spilled oils, fuels, and petroleum products : 1. composition and properties of selected oils.

Benzene – µg/g BTEX – µg/g
Alaska North Slope Crude Oil (2002) 2866 16300
Alberta Sweet Mixed Blend (ASMB, Reference #5) 2261 18170
Arabian Light (2000) 979 10950
Sockeye (2000) 1343 8230
South Louisiana (2001) 1598 12210
West Texas Intermediate (2002) 4026 23370

If you want to look up the value for every major oil out there Environment Canada maintains an oil properties database


This entry was posted in Oil Sands, Pipelines, Trans Mountain, Uncategorized. Bookmark the permalink.

5 Responses to Once again a group of health professionals gets the science wrong on diluted bitumen and the Trans Mountain Pipeline Expansion project

  1. Tyler says:

    I should have guessed CBC before I clicked the final link at the bottom.


  2. Alison Malis says:



  3. Nelson Wayne W Liston says:

    As Ben Redekop wrote about anti-nuclear zealot, Dr. Helen Caldicott, her “self confidence was rooted in part in her identity as a physician”.
    Physicians for Social Responsibility (to which several of these letter signatories adhere) which organization Dr. Caldicott revived in the early 80’s, after abandoning her medical career for full time activism, found her “unconcern for strict scientific accuracy in favor of politicized and emotion-inducing appeals was undermining PSR’s credibility.”
    Would that such concerns were still present in today’s use of the policy based “science” weapon of which Eisenhower warned, to club different views into silence.


  4. Nelson Wayne W Liston says:
  5. Ruud Hommel says:

    Much funnier and more recent is this link: https://www.youtube.com/watch?v=YjFWiMJdotM
    Dutch TV comedian, but with English subs. You’re bound to miss some of the funny remarks.
    If only someone would stand up and do something like this on TMX.
    By the way, you might have seen this one: https://www.youtube.com/watch?v=ELD2AwFN9Nc
    Have fun


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