Steep Hill, ACCL Find Pesticides in Over 50% of Cannabis Samples

By Aaron G. Biros

With voters legalizing recreational cannabis in four new states including California, there is a much larger public health concern at hand.

On Election Day, voters in California passed Proposition 64, establishing a recreational cannabis market and regulatory environment. While the state won’t issue the first licenses under the new regulatory scheme until 2018, the medical cannabis industry is already well established.

Steep Hill Labs, Inc., based in Berkeley, California, found in October that 84.3% of samples submitted tested positive for pesticide residue, according to a press release. The announcement came before Election Day, but is particularly eye opening given the massive new market created overnight by Prop 64.rsz_steephill_lab_images_25_of_415_copy

Particularly concerning is their detection of Myclobutanil, which was found in more than 65% of samples submitted to the lab. According to the press release, when Myclobutanil is heated (i.e. smoked or vaporized), it is converted to Hydrogen Cyanide, which is extraordinarily toxic to humans and can be fatal in higher doses.

Reggie Gaudino, Ph.D., vice president of scientific operations and director of genetics at Steep Hill Laboratories. (photo credit: Preston Gannaway)
Reggie Gaudino, Ph.D. (photo credit: Preston Gannaway)

According to Reggie Gaudino, Ph.D., vice president of science, genetics and intellectual property at Steep Hill, their more recent study shows they detected pesticides in roughly 70% of the samples they received and 50% of those contained Myclobutanil. Gaudino says that up to a third of those samples would have failed under Oregon’s regulatory standards.

If a lab test were failed, it would contain pesticides at or higher than the required action level. Oregon’s action level, or the measured amount of pesticides in a product that the OHA deems potentially dangerous, for Myclobutanil is 0.2 parts-per-million (PPM). Steep Hill’s instrumentation has a method detection limit down to the parts-per-trillion (PPT) level, which is a more precise and smaller amount than Oregon’s action level.

“Those in the cannabis community who feel that all cannabis is safe are not correct given this data – smoking a joint of pesticide-contaminated cannabis could potentially expose the body to lethal chemicals,” says Jmichaele Keller, president and chief executive officer of Steep Hill. “As a community, we need to address this issue immediately and not wait until 2018.”

Potentially harmful pesticides, and specifically Myclobutanil, have been detected in Colorado and Washington’s recreational markets on a number of occasions, proving this is a widespread issue. Steep Hill’s release suggests that California regulators take a look at Oregon’s pesticide regulations for guidance when developing the regulatory framework.

What’s even more troubling is that not all laboratories have or had the capability of detecting pesticides at sufficiently low levels and because of this, other labs had significantly lower rates of pesticide detection, suggesting possible inconsistencies in testing methods, instrumentation, sample preparation or other variations. During a 30-day period in late September and early October, Steep Hill found, using publicly available data, or data from contracted testing, that other labs were only reporting between 3% and 21% pesticide detection.

Examination of cannabis prior to testing- credit Steep Hill Labs, Inc.
Examination of cannabis prior to testing- credit Steep Hill Labs, Inc.

It is important to note that those samples were not identical and there could be a great degree in variation on the quality of samples sent to different laboratories, so it is not an entirely accurate comparison. Steep Hill does however detect pesticides down to the parts-per-trillion level, whereas many common methods for detecting pesticides look at the parts-per-billion level.

Reggie Gaudino says the Association of Commercial Cannabis Laboratories (ACCL) is using this data to work with Steep Hill and a number of other labs to address these issues. “As a member of the ACCL, and after discussion with ACCL, we have agreed that all future discussion of this issue should not include laboratory names, as this is about educating the industry in general, and making sure all members of the ACCL are developing the best possible methods for detecting pesticides,” says Gaudino. “The ACCL has responded to this data, by inquiring on a larger, industry-wide basis, which represents a better picture of the issue, rather than only in California’s still-technically unregulated market.” The important message is this is a major issue that needs addressing urgently. “As such, the troubling issue remains, across the larger ACCL membership, there is still detection of pesticides in at least 50% of the cannabis being tested.”

ACCL logoAccording to Jeffrey Raber, Ph.D., president of the ACCL, the industry is experiencing a pesticide problem, but it is very difficult to quantify. “It is fair to say that around 50% of the cannabis being tested contains pesticides, but we really don’t know that exact number until a much more comprehensive statistical analysis is performed,” says Raber. “We agree this is a big problem and that it needs to be addressed, but we are not sure just how big of a problem it really is.” With so much variation in labs in a state where not everyone is required to test products, it is very difficult to pin down how consistent lab results are and how contaminated the cannabis really is. “If all of the labs had the same methodology, samples and shared statistical analyses for a real study then we can look at it closely but it seems we are a ways off from that. I can say confidently however that this is a pretty significant problem that needs addressing.”

Still, Steep Hill detecting pesticides in a majority of their samples and some labs finding as little as 3% should raise some eyebrows. “Unfortunately, our recent study discovered that 84.3% of the samples assessed by our triple quadrupole mass spectrometer contained pesticides,” says Keller. “As of today, this tainted product could be sold in most dispensaries throughout the state of California without any way of informing the patients about the risks of pesticide exposure.”

These findings could mean potentially enormous health risks for medical and recreational cannabis consumers alike, unless regulators, labs and growers take quick action to address the problem.


  1. Robert Rosendaelli


    Thank you for sharing this article.

    What would you suggest as trusted resources/growers/brands/shops in Los Angeles to obtain cannabis that is healthy for consumption?

    There are a myriad of dispensaries and the marketplace is flooded, and budtenders can almost never provide lab testing for anything upon request.

    I look forward to your response.


    Robert Rosendaelli

    1. Aaron Biros Post author

      Hi Robert,

      That is an interesting and very important question. I have also experienced those issues firsthand, so you are not alone. I have visited dispensaries that are required by law to have laboratory test results on hand, yet time and again they are unable to produce them. This is an all too common and I sympathize with consumers in the current market. It is hard to do due diligence on cannabis processors or growers. It’s also virgin territory because for any other consumer product, like beer or food, you generally do not think about the safety of that product when you purchase it. So it requires a new type of thinking unfamiliar to most. Do some background research on companies that might market themselves as having robust safety and quality procedures in place. Ask questions about what they do to keep their products safe and, if they are smart and trustworthy brands, they should provide you with plenty of information on exactly what they do.

      From a consumer’s point of view, I would recommend looking for companies that use third party certifications like Clean Green Certified. It is not a guarantee that the product ingested is safe and sustainable, but it is the next best thing. I hope this helps!

  2. James Christopher Hill

    The concern I have after 90 years of smear campaigns against marijuana use is that “suddenly” there is a pesticide problem. For all those years and all the test data, there has never been a reported or recorded death as to the use of cannabis, in face a rate of zero versus 89,000 and growing alcohol deaths, 145,00 or more from smoking with of course is loaded and packed with pesticides, toxic chemicals that are highly carcinogenic. The medical cancer society may be throwing crumbs at the population to quill any concerns of purposeful blocking of medical marijuana and cannabis oil specifically. What better way to keep marijuana illegal than by using more scare tactics as before. Frankly, despite all the experts, I smell a fish. Why just marijuana all of a sudden and not any of the other crops as I would figure the pesticides would be just as harmful that is laden on all of the food we consume now with protection for Monsanto for no GMO labeling. Frankly, I still, despite this article, would consider even tainted marijuana with the 80-90% positive sample of pesticides, to still be safer to consume than the food we eat or the air we breath. In addition, If this is true, then the case of growing marijuana versus other more delicate crops should be easily rectified by banning the use of certain pesticides on marijuana. We are killing bees with pesticides by the millions even today as just my local nearby country, while spraying for mosquitoes, killed over 10 million bees from local bee keepers and all they have received is an apology. If this is true, then fix it, how hard is it to simply ban the use of a certain pesticide!? We’ve done it before. Plus MJ can be grown in a stable and controlled environment much to the added profit of pure cannabis production in shorter times. So naturally, when I read something like this, red flags go up. There are millions of dollars pouring into congress and well placed former Monsanto executives and FDA advisors in our various departments we simply know the truth and this article seems to be another way of saying “NOPE”, told America so…so that the medical community, big pharmacy, even powerful and very well connected drug dealers along with expensive “toy” manufacturers are all whispering in congress’ ears to keep marijuana illegal. We have got to be the most gullible country in the world and even when Ansligner managed to get Congress to ban marijuana, they KNEW it was safe and all the false propaganda claims and campaigns ran by Anslinger and his special interest group organized just so they could keep funding going. In 1973, Nixon was urged by his JSS advisor that it was time to decriminalize marijuana. Nixon of course refused vehemently and then created the DEA in response. A incredible failure on the war on drugs and $1 Trillions dollars later, the year 2017 is showing Americans waking up to the truth, but with articles like these abounding and more will come as old dinosaur politicians that drink like fish, smoke, etc demand they keep America “Safe” from that Hippie drug. It’s an herb with over 200 medicinal uses and it’s obvious that certain parties do NOT ever want marijuana legalized. I’ll grant if it is pesticides, then fix it.

    1. Joaquin

      That’s because steep hill is a subsidiary of harborside health center. Both companies which are really one company spread mass hysteria style propaganda about cannabis in order to secure business. Plain and simple one of the founders of steep hill Addison Demoura who also sits on the board is a complete disgrace. He at one point helped Stanislaus County sheriffs and dea agents to bust others in the medical Marijuana field who he considered adversaries.

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