A lot of outdoor gear has warnings like the following,

WARNING: This product contains chemicals known to the State of California to cause cancer and birth defects or other reproductive harm.

while sometimes it says

may contain chemicals

To keep this questions from being too broad, I am going to limit it to just fuel canisters. While there are carcinogens produced by operating a canister stove, a campfire will also produce them and I am unaware of any canister fuels that lack the warning.

So how much should I worry/care about these warnings?

  • 3
    You get the same warning on coffee now, in California... businessinsider.com/california-cancer-warnings-coffee-2018-4
    – njzk2
    May 17, 2018 at 5:35
  • 2
    Significant quote from njzk2's link: "A chemical needs to have only a one in 100,000 chance of upping your risk for cancer to merit a written warning to consumers." I've always wondered how it is that something can become known to the State of California that the rest of the world doesn't know. The more I learn, then more I feel that Prop 65 was big joke.
    – cobaltduck
    May 17, 2018 at 13:41
  • 1
    The "cancer causing chemicals" are likely in the actual canisters construction rather than the fuel itself. Paint, the metal used etc
    – Nate W
    May 17, 2018 at 22:11
  • "May contain chemicals"? Heh. Don't they know that everything is chemicals? Good grief. High school dropouts, then, possibly. Without chemicals, you can survive 3 or 4 days, but that's it, then you're dead. May 19, 2018 at 0:54
  • 1
    And what do they think people are made of?
    – ab2
    May 19, 2018 at 6:13

2 Answers 2


Most of the time, the "Known to the State of California" warning is an incantation to ward off lawyers. That's not true for fuel.

White gas/Coleman fuel/whatever-it's-called has significant amounts of benzene, a known carcinogen, in it, as does kerosene; other hydrocarbon fuels will have trace amounts. Benzene is destroyed during combustion, but the vapors from unburned fuel are a hazard. Make sure you close the fuel bottle tightly when it's not in use, handle the fuel outdoors or in a well-ventilated area, and make sure your stove is burning cleanly (it should produce a blue flame indicating complete combustion; a yellow flame indicates that the fuel isn't being fully burned).

This is a great example of why that warning is a problem: the occasional real hazard (such as benzene in fuel) gets lost in a sea of empty statements.

  • Still, probably the hazard due to the vapors being inflammable is higher than the cancer risk - and also the total benzene exposure due to traffic (at least for people normally living in cities) is higher for most people than the exposure due to camping fuel. (Which is an addition to Mark's very valid point that indiscriminate warnings will confuse the sense of danger to the point where the real dangers are hidden) May 22, 2018 at 0:34

You should not consume the canisters or warning labels while in California.

Seriously they are not actually very helpful, since they have neither the chemicals nor specific risks. The list of possible chemicals is pretty long and varied.

If you know what you are using (a component of gasoline) there are specific fact sheets.

Generally the OSHA acceptable exposure limits are in ppm for a short term exposure, in well ventilated spaces with small sources like one would expect for camp stove use you are pretty unlikely to surpass that. Though there is no certainly safe dose of most chemicals.

  • "No safe dose of most chemicals"? Are you saying there's no safe dose of water? May 19, 2018 at 1:02
  • @DonBranson yes.
    – user8348
    May 19, 2018 at 14:23
  • I love your dry humor. May 19, 2018 at 14:34

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