Insights
Publication Date: June 19, 2025
The International Agency for Research on Cancer (IARC) recently re-evaluated the carcinogenicity of automotive gasoline and several gasoline additives, such as MTBE and ETBE, and have now classified automotive gasoline as a Group 1 hazard for the development of two cancers.
In this video, Dr. Allison Stock discusses IARC’s latest findings at their meeting in February 2025 and her invitation and participation as an observer at the meeting.
Dori Marlin: Dr. Stock, can you tell us exactly what IARC looked for in this latest review and also give us details on the findings?
Dr. Allison Stock: Absolutely. So, the International Agency for Research on Cancer, or IARC, re-reviewed gasoline, and we're talking about automotive gasoline -- not marine fuels, not jet fuels, not diesel fuels.
But we're talking about the kind you put into a vehicle or another combustion-powered engine that uses gasoline and not diesel. IARC in 1987 to 1988 published their first monograph on gasoline. So this is an update to that original monograph that was published.
IARC pulled together a working group of scientists from all over the world, and these are individuals that are working at universities and public health agencies who come together both in person and also online, and review all the literature that's out there on gasoline.
They have 4 main areas that are looked at:
They spent quite a bit of time looking at the literature on gasoline exposures and what they have determined is that long-term exposure to gasoline vapors -- and remember, this isn't the exhaust, this is the vapors -- in certain settings may be associated or can be associated with the development of acute myeloid leukemia and bladder cancer.
It's really important to understand that when IARC does the review, they're not looking at a dose. They're only assessing a hazard, so they have just looked to see, “Can this be associated?” They're not telling us how much they need to have the development of any cancer.
This is important because a central tenet of toxicology, epidemiology, and a lot of other sciences is, “the dose makes the poison.”
We can't assess risks or likelihood of development of cancer unless we know how much someone has been exposed to and we have to set some threshold level above which we would see cancers.
That has not been done and that is going to impact the regulatory environment around gasoline because we don't know how much you need in terms of a long-term exposure to be associated with the two cancers that IARC has found it to be associated with.
Dori: That's a lot of information, great information. What do companies then need to know about these findings further, and is there anything that they can do to prepare or mitigate this potential risk in advance?
Dr. Stock: The good news is that most corporations out there have already taken steps to mitigate or reduce exposures to gasoline because the areas that we are going to have the most exposures would be in places like a refinery and there are other things there besides gasoline that we’re concerned about.
So they're using what we call Personal Protective Equipment (PPE) already in those environments and without knowing the hazard, it's really hard to create regulatory standards and safe handling practices around an agent. So the nice piece here is that some of that's already been done in these settings as I mentioned -- a refinery, other places could be a terminal, which is where the refinery ships the gasoline and it sits in a big storage tank and it gets loaded onto trucks, or gas station attendants that have had long-term exposure to gasoline -- we can't tell them what the level would be that they would be concerned about. So what we do, and we help corporations do this, is set up plans and safe handling practices so that we can prevent those exposures.
Dori: Very good, Dr. Stock. We really appreciate your help informing all of us on this topic and for more information, you can stay with us at jsheld.com/insights.
Dr. Allison Stock is a Senior Vice President in J.S. Held’s Environmental, Health & Safety practice. Dr. Stock leads the Health Sciences service line within J.S. Held’s EHS practice. She specializes in human health risk assessments combing both toxicological and epidemiological data. She has expertise in petrochemicals; pharmaceutical agents; environmental permitting; property transfer; environmental, social, and health impact assessments; inhalation toxicology; renal toxicology; drug and alcohol exposures; toxicological and epidemiological risk assessment; communicable and foodborne illnesses such as Legionella, Salmonellosis, and Pseudomonas infections; rapid needs assessments; emergency response; ambient and indoor air monitoring; occupational health and safety plans; and stakeholder communications.
Dr. Stock can be reached at [email protected] or +1 504 420 1896.
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