Refresh Checked Unchecked Menu Search Shopping bag Geolocation Person Facebook Instagram Twitter YouTube Info Icon CBC Icon CBC Shape CBD Icon CBD Shape CBG Icon CBG Shape THC Icon THC Shape THCV Icon THCV Shape Loading…
Advertise on Leafly

Leafly Investigation: How Much Butane in BHO Is Too Much?

December 12, 2016

On Jan. 1, 2017, Colorado will raise its state-regulated limit on the residual levels of volatile solvents allowed in cannabis concentrates. It’s a little-noticed rule change that involves dramatically increased levels of allowable solvents. Among the changes:

  • The legal threshold for butane, the solvent that puts the B in BHO, will increase more than sixfold, from 800 parts per million to 5,000 ppm.
  • Allowed residuals for heptanes, another class of solvents, will go up by a factor of 10.
  • Xylenes, industrial solvents that technically aren’t allowed to be used for cannabis extraction at all, will be permitted at concentrations of up to 2,170 ppm—significantly higher than the previous limit of less than 1 ppm.
  • The state residual limit on benzene, perhaps the most hazardous chemical of the group, will double from less than 1 ppm to less than 2 ppm.

A redlined version of Colorado state testing regulations highlights the changes to residual solvent limits in the state, set to take effect Jan. 1. Click to expand image. (Colorado Department of Revenue)

“Consumers are going to feel like they might taste it.”
Mike Van Dyke, Colorado Department of Public Health and Environment

On the surface, these are staggering increases in chemicals that, at some levels, have been associated with nausea, irregular heartbeat, increased risk of cancer, and even death. Regulators, testing laboratory operators, and industry members in other states have expressed surprise at the changes, which will apply to both adult-use and medical markets. Mike Van Dyke, chief of the Environmental Epidemiology, Occupational Health, and Toxicology Branch at the Colorado Department of Public Health and Environment (CDPHE), which recommended the new limit, acknowledged that concentrates capable of clearing the regulatory hurdles could be noticeably different from what’s currently allowed.

“Consumers are going to feel like they might taste it,” he said of new allowed butane levels. “They might smell it.”

“I’m surprised nobody else has even actually been interested in this,” he told me in an interview last week.


Leafly’s Visual Quality Guide to Selecting Cannabis

There are a few things CDPHE’s Van Dyke wants to make clear about the new rules. Here is one: “This change was not a result of any industry pressure.”

The increase didn’t come at the behest of lobbyists, he told Leafly. “In fact, in the workgroups, if we heard anything from industry, I think we heard the other side, that these were too high,” he said, “which is an uncommon place to be.”

What Is Going On?

The justification for the change, according to Van Dyke, is that the new limits truly follow the best currently available medical and scientific guidance. “This was a re-evaluation based on trying to make things health-based,” he explained. “These numbers came from the international harmonized guidelines for residual solvents in pharmaceuticals.”

Van Dyke is referring to a published scientific article he cited in a July letter to Jim Burack, director of the Colorado Department of Revenue’s enforcement division, which is in charge of enforcing the new standards. Van Dyke provided the letter and spoke at length to Leafly about the coming change.

“Will these numbers stand the test of time? I don’t know,” he said. “We’re open to new data that comes out, but our goal is to make sure that we maintain, the best we can, the best evidence-based regulations for health.”


U.S. Attorney General Says Cannabis Is Not a Gateway Drug

The agency is trying to do precisely what it’s been asked, Van Dyke said. Legislation passed this year, House Bill 16-1261, put the CDPHE in charge of recommending testing standards “based on medical reports and published scientific literature.”

When the Colorado Department of Revenue set the previous limits, in the wake of Amendment 64’s passage, it was a “fast and furious” process, Van Dyke said. “There were times you came up with numbers because that’s what you came up with at the time.” Despite the eye-popping increases, he said the new limits adhere more strictly to the latest available evidence in scientific research.

Click to expand image. (Amy Phung/Leafly)

Comparison Shopping

Other jurisdictions have set residual solvent limits lower than Colorado. Berkeley, Calif., limits total combined residual solvents at 400 ppm. Oregon, on the other hand, set standards similar to Colorado, but with more solvents identified. In a report explaining its own rulemaking process, the Oregon Health Authority cited the same international pharmaceutical standards as Van Dyke’s letter did. Washington, which was initially silent on residual solvents levels, has considered limits as low as 500 ppm butane and 0.1 ppm benzene, but regulators are currently proposing the state adopt higher limits that match those now embraced by Oregon and Colorado. After a public comment period, the new Washington limits are set to take effect in late February.

“Frankly, we’re not saying that extracted marijuana products should have 5,000 ppm of butane in them,” Van Dyke, in Colorado, said. “What we’re saying is 5,000 is a health-based limit.”

But didn’t he just acknowledge the possibility of literally smelling butane in BHO approved by the state for medical patients?

“I think there may be a lot of market drivers that push those numbers lower,” Van Dyke acknowledged, and smell could certainly be one of them. But, he repeated, “it’s not from a health perspective that those numbers should be lower.”

But are residual solvents merely a matter of product taste and quality, or is scientific research still too limited to inspire consumer confidence? It may be a little bit of both.

There’s been almost no research into these solvents in the context of cannabis.

A Knowledge Problem

A lot of eyes widened when I talked to people who weren’t aware of Colorado’s new standards. Some consumers believe that industrial solvents are inherently hazardous to their health and should be avoided at virtually any level. Many concentrate consumers now opt for solventless extracts, such as rosin or bubble hash. Others don’t worry as much, pointing out (accurately, according to most scientists I talked to) that someone who smells a whiff of butane from a Bic lighter has already inhaled way more than they’ll get in a day of dabbing.

“It’s not the butane,” said Nick Mosely, co-owner and chief science officer at Confidence Analytics, a cannabis testing laboratory in Washington state. “The butane is really not a huge health risk,” he said, adding that it “takes quite a bit”—way more than you’d get from dabbing or a vape pen—to cause serious harm such as liver damage.


Pesticides 101: questions and answers for cannabis patients and consumers

A 1981 study cited by the US Department of Health and Human Services found that exposure to 10,000 ppm for 10 minutes may lead to drowsiness but doesn’t appear to cause systemic effects in humans. The average dab consists of about 10 milligrams to 20 mg of concentrate, Mosely at Confidence Analytics said. In the eyes of Colorado regulators, he added, “these Class 3 solvents are not cause for concern at 5,000 ppm when the dose of the substance is so low.”

“Can’t you err on the side of caution, though?”
Jeffrey Raber, The Werc Shop

Mosely did call the levels of xylenes and benzene in Colorado  “concerning.”

“The issue” with xylenes and benzene, he explained, is that “the contaminants are unintentionally there.” In other words, those chemicals aren’t part of the extraction process. Those chemicals are sometimes used to clean equipment and may inadvertently become part of the final product. They’re also sometimes found in low-quality solvents—in other words, they’re contaminants in the contaminant. Mosely wasn’t trying to criticize Colorado’s new limits from a health perspective, though he didn’t sound especially jazzed about the idea of finding those residual levels in a concentrate, either. He just meant that a higher—but soon-to-be legal—level of residuals could indicate careless extraction methods or low-quality products.

There’s no question that these solvents, at certain levels, are dangerous. Many, at high concentrations or over long periods of exposure, have been linked to all sorts of negative health conditions, ranging from irregular heartbeat and nausea to cancer and bone marrow failure. Most are tightly regulated in other contexts. Consider benzene. The US EPA limits the chemical concentration in drinking water, for example, to 0.005 ppm (that’s 5 parts per billion), while the Occupational Safety and Health Administration limits workplace exposure to 0.005 ppm . Colorado’s limit in concentrates, by contrast, is 2 ppm—twice the previous level, but the most modest increase of the bunch.


How California Lab Testing Could Change the Way We Talk About Cannabis

But there’s a familiar problem: There’s been essentially zero research into these solvents in the context of cannabis. As a BuzzFeed headline put it last year, “Wax Is Weed’s Next Big Thing And No One Knows If It’s Safe.”

The claim might be sensational, but it contains an important grain of truth. When regulators and industry try to keep residual solvent levels low, it’s not because they know exactly about how those chemicals behave when you vaporize them. Nobody’s really studied that. Most Americans in 2016 still think dabbing is a style of dance.

Effect of xylene on the nervous system

Concentration of xylenes Symptoms
100–200 ppmNausea, headache
200–500 ppmFeeling "high," dizziness, weakness, irritability, vomiting, slowed reaction time
800–10,000 ppmGiddiness, confusion, clumsiness, slurred speech, loss of balance, ringing in the ears
> 10,000 ppmSleepiness, loss of consciousness, death
Source: Journal of Oral and Maxillofacial Pathology, available at

Agencies that do try to pin residual solvent levels to published scientific data are extrapolating from all different kinds of information. Sometimes it comes from research into solvent exposure among industrial workers. In Colorado and Oregon, health agencies looked to how pharmaceutical production guidelines dealt with residual levels.

Jeffrey Raber is one of the most respected voices in the cannabis testing industry. He runs the Pasadena-based testing lab The Werc Shop and has worked to help educate regulatory bodies in eight states on testing issues. He feels that relying on pharmaceutical guidelines misses an important point. While some solvents might be necessary to make life-saving drugs in a pharmaceutical context, not all solvents are crucial to cannabis extraction.

“In cannabis, you know that you can utilize things that are much, much more physiologically benign,” Raber said. “You’re not forced to use benzene.”


How to Make Rosin Dabs

This puts the cannabis industry in a somewhat unusual position. Existing best practices for cannabis extraction far outstrip Colorado’s new regulatory limits. If anything, the new regulations might be seen as discouraging best practices.

“I think the argument to that,” Van Dyke said, “is we’re setting health-based standards.”

I ran that response by Raber. “His perspective makes sense,” he replied. “The regulators always worry they are going to revoke someone’s license based on the regulations.”

When it comes to protecting consumers, Raber added, “can’t you err on the side of caution, though?”

Is It Worth Worrying?

Knowing how to react to Colorado’s new testing limits requires a clear understanding of how residual solvents behave. We don’t have complete clarity on that yet. But there are some things consumers might consider as they decide how to respond to the new change.

“If someone is really trying to do right by the medical market, they would be doing best to not be using butane.”
Jeannine Machon, CMT Laboratories

Nearly all commercial concentrate producers in Colorado now consistently comply with the existing lower limits on residual solvents, said Jeannine Machon, owner of CMT Laboratories in Denver. Machon, a member of the Colorado working group that devised the new limits, doesn’t expect extractors to drop their quality level. “They’ve already all figured it out,” she said. “I don’t believe that they would willingly allow more butane to sit in the sample.”

For consumers concerned about the new limits, there’s an easy answer. It’s not difficult to avoid volatile solvents entirely—at least in regulated markets. Some concentrates, such as rosin and bubble hash, are made without any solvents. Others use carbon dioxide as a solvent. Staff at most reputable retail shops know the difference.


25 Things to Expect in Newly Legal States

“If someone is really trying to do right by the medical market, they would be doing best to not be using butane,” Machon said. “But the market needs to drive that, not the regulators.”

When new evidence does come along, Van Dyke said Colorado regulators will be ready to adapt. “We have the ability to change those regulations as new data comes out and as new issues emerge,” he said.

State regulators are aware of the data gaps. “We don’t have a good concept of what is an average and what is a maximal consumption of a concentrate by a user,” Van Dyke said. On that front, the Colorado Department of Public Health and Environment played it safe, assuming a use rate of 10 grams of extract per day. Even the heaviest of concentrate consumers rarely top more than 2 grams per day.

Why Colorado’s Limits Matter

What happens in Colorado often sets the standard for other emerging legal markets and state regulatory systems.

Jane Stewart, marketing manager for SC Labs, a Santa Cruz-based testing lab, sees the effect in California. “Because we live in a state that’s unregulated, California is oftentimes looking to Colorado, Oregon, or Washington, states that maybe have regulatory bodies in place that are a little bit ahead of us,” she said. When I told her about Colorado’s new standards, she seemed surprised. “I wonder how all the regulators came to those decisions,” she said. “I would love to know more. It would be very important to my business.”


California Just Legalized Cannabis! Now Comes the Hard Part

SC Labs is a major player in California. It was the lab responsible for testing all the concentrate entries in this year’s Emerald Cup, a longtime growers’ fair in the heart of California’s Emerald Triangle. This past weekend the cup hosted an estimated 30,000 visitors at its annual event.

I asked Stewart what a typical residual solvent level might be for concentrate entered in the Cup (results are posted online). Her response made clear that some of the cannabis world’s savviest consumers have already moved beyond BHO.

“The Emerald Cup is a solventless competition,” she said simply.

Ben Adlin's Bio Image

Ben Adlin

Ben Adlin is a Seattle-based writer and editor who specializes in cannabis politics and law. He was a news editor for Leafly from 2015-2019. Follow him on Twitter: @badlin

View Ben Adlin's articles

  • PlacidDream .

    why i love making my own BHO but it gets tedious sometimes and prices are getting better so i find myself doing it less. Now it just sniff and guess how much butane or what ever other solvents are in the product.

  • Sam Parent

    TBH i think all butane is bad. i wont smoke it, let alone buy it. the taste alone kills me. CO2, LHO, or dry sift should be the only legal ways of making this substance.

    • @nsmartinworld

      Why should your preference be enshrined in law? Buy what you want, and let others buy what they want. Why wouldn’t that occur to you?

  • Jim Shaw

    do you think it’s a way for law to use this against the industry ,ex, well the higher numbers could cause health problems leading them to band cannabis for good

    • Excuse me

      My first thought.

    • Clabian

      First thing that popped into my head.

    • lovingc

      Paranoia set in?

  • Matthew Gleason

    This is a pretty scare-tactic-y article. I think the author maybe missed some of the subtler implications here. The allowed amounts of these solvents is still so low that it really isn’t a health risk. There is a 2-part reason why that’s not an issue. Both stem from the fact that Colorado’s daily expected intake with these numbers was 10g of shatter. This is a tiny amount of something to consume daily when compared to something like water where the expected daily intake is much higher than that. You have to assume that someone can drink gallons of water a day and be fine in order to set a level on a chemical byproduct, but the user expectation is only 10g of shatter in CO. The second part is that 10g is insanely high. You can find a couple internet videos of someone trying this, but there probably isn’t anyone in Colorado who gets more than 2g a day, so they really did, at minimum, a 5-fold decrease in allowable solvents from the standards outlined in the paper. They did the calculations that are in the recommendations of the paper, but set the expected intake to 5 times what is really plausible for their highest intake user, so it’s really much smaller than he realizes.

    • lovingc

      Never purposely ingest a poison.

      • @nsmartinworld

        “The dose makes the poison.” First rule of toxicology.

      • Zachary Iszard

        Do you ever drink anything with ethanol in it? That’s technically a poison. @nsmartworld is 100% correct.

        • lovingc

          Not since I became a diabetic.

  • Mark Esau

    The toxicity of butane is low and The Acute Exposure Guideline Levels (AEGLs) for butane are higher than 5,000 ppm.

  • Clabian

    It’s pretty scary that Colorado is raising the limits so high on residuals in concentrates. Most other states look to Colorado when they model their Medical/ legal Cannabis. It’s not the butane that’s really scary, it’s xylene and benzene! Seriously this sounds like a terrible move at the cost of the public’s health. I sincerely hope the Cannabis community speaks up against this increase. I also hope that this doesn’t allow for reckless concentrate makers to break into the market.
    It seems like most concentrate makers keep to pretty high standards with their products after all they want a good name for their company and if someone got sick from their products it would ruin them. I hope other states look to this as a reckless move and avoid putting people’s health in danger. This is opening the door for crackpot extractors entering the market to make a quick buck at the expense of consumer’s health.
    Also this feels like they’re allowing some amount of error to occur so public perception of legal cannabis can be turned against the industry.

  • Jake Wilson

    “Effect of xylene on the nervous system” is a chart you copied from Wikipedia concerning inhaling the gas vapors and is in no way at all related to the concentration ppm in hash oil. The 2,170 ppm means there is only .02% leftover or unpurged from the product. So scary. Not. Just an fyi. I’m only going to mention this one fact, not the rest I observed reading this article.

  • Joe

    Concentrates, why! There are so many groups trying to take over. You the consumer are been taken. You body will adsorb no more no less. It is base on you health and the quality of the marijuana “quality ” the effect you will get depent on the strain. A concentrate has residual solvent. Did you know that those solvents will store in your body fat. Fat cells that you use normally to generate energy. And no you do not function better with solvents running true you liver and kidneys. Have you hear about dialysis. That is what you will end hook to a dialysis machine. Well, have not hear of any marijuana deads, but you will be hearing about kidney failure from using consentrates.

    • Dave_sNotHere

      Hey Joe, where you goin’ with that gun in your hand?

  • nathan sandiego

    Simple population control.

  • lovingc

    The only solvent I have ever used is ethanol it is potable and easy to get (Everclear). It works well in an isomerizer and makes great oil.

    • MrGordon Swanson

      ethanol the friendly molecule

  • Darius A Stokes

    Use oxygen for the BHO. Works better and environmental friendly pays less in the long run. Methane is a contain chemical it belongs in a container.

  • Aging Ent

    QUOTE —
    “Consumers are going to feel like they might taste it,” he said of new allowed butane levels. “They might smell it.”
    “I’m surprised nobody else has even actually been interested in this,” he told me in an interview last week.

    Actually here’s me 3 weeks ago at the Washington State Liquor and Cannabis Board at 40:30 on here, talking about Washington’s proposed raised levels to match Colorados –

    I’m highly concerned about this and you should be too! If incredible products that are on the market (see my reviews of impeccable products at and all this product can come in at under 500ppm of everything right now, and land on the pass/fail side for testing of xylenes and other unwanted chemicals like isopropanol at levels that can lead to blindness if it were ingested orally.

    Why on earth would they need to escalate up to 5000ppm and allowances for 1250, 1650, or 3500 ppm for these chemicals? It’s unnecessary as demonstrated by the current market state, and only increases the potential for deleterious effects. So therefore, in the interest of safety they should not increase these levels.

  • @nsmartinworld

    Manufacturers can market their products as low-residue, certified by an independent testing standard. Problem solved.

  • colvin

    I wonder what my sister’s life would have been if not for the timely
    intervention of Peter Hurt, who came to the rescue of my sister
    life when the Doctors here in Tallahassee, FL gave her just few months to live.I really appreciate brother Tulip $ sister Elisabeth for their timeless effort to get a cure for our sister by searching over the internet and giving me doctor Peter’s phone number after several effort to get a cure for my sister. Just last week the doctors who once said my sister only have few months to live just confirmed she is now cancer free of the brain after 3 months of using Doctor Peter’s CBD/THC Oil .Thank you so much brother Tulip/sis Elisabeth and Doctor Peter Hurt for saving my sister life phone #(804) 537-0917


    got some medical marijuana and Cbd/Thc oil from Dr peter hurt via Phone number +18045370917

  • Wade Rawluk

    The question of the article has a false assumption, namely that there is a safe level of butane. There is no safe level of butane and anyone who says otherwise is either a fool or liar. Just stick to non-solvent concentrates like dry sift hashish, bubble hashish or rosin and be safe

  • rebecca.j

    Get BHO here