Legal marijuana sales creating escalating damage to the environment

A dried flower bud of the Cannabis plant. Credit: Public Domain

Marijuana sales have created an economic boom in U.S. states that have fully or partially relaxed their cannabis laws, but is the increased cultivation and sale of this crop also creating escalating environmental damage and a threat to public health?

In an opinion piece published by the journal Environmental Science and Technology, researchers from the University of North Carolina at Chapel Hill and Lancaster University in the U.K. have called on U.S. federal agencies to fund studies that will gather essential environmental data from the legal cultivation farms and facilities.

This information could then be used to help U.S. states minimize any environmental and public health damage caused by this burgeoning industry and aid legal marijuana growers in making their business environmentally sustainable.

State-by-state legalization is effectively creating a new industry in U.S., one that looks set to rival all but the largest of current businesses. In Colorado alone, sales revenues have reached $1 billion, roughly equal to that from grain farming in the state. By 2020 it is estimated that country-wide legal marijuana sales will generate more annual revenue than the National Football League.

But the article, titled "High Time to Assess the Environmental Impacts of Cannabis Cultivation" co-authored by William Vizuete, associate professor of environment sciences and engineering at UNC's Gillings School of Global Public health and Kirsti Ashworth, research fellow at Lancaster University's Lancaster Environment Centre say that this expanded cultivation carries with it serious environmental effects.

Their article points out that cannabis is an especially needy crop requiring high temperatures (25-30 °C for indoor operations), strong light, highly fertile soil and large volumes of water - around twice that of wine grapes. In addition, the authors state that the few available studies of marijuana cultivation have uncovered potentially significant environmental impacts due to excessive water and energy demands and local contamination of water, air, and soil.

For example, a study of illegal outdoor grow operations in northern California found that rates of water extraction from streams threatened aquatic ecosystems. High levels of growth nutrients, as well as pesticides, herbicides and fungicides, also found their way back into the local environment, further damaging aquatic wildlife.

Controlling the indoor growing environment requires considerable energy with power requirements estimated to be similar to that of Google's massive data centers. No significant data has been collected on the air pollution impacts on worker's public health inside these growing facilities or the degradation of outdoor air quality due to emissions produced by the industrial scale production of marijuana.

The authors emphasize, however, much of the data on marijuana cultivation to date has come from monitoring illegal cannabis growing operations.

Dr Ashworth of Lancaster Environment Centre said: "The illegal status of marijuana has prevented us from understanding the detrimental impacts that this industrial scale operation has on the environment and public health."

"This is an industry undergoing a historic transition, presenting an historic opportunity to be identified as a progressive, world-leading example of good practice and environmental stewardship."

The continued expansion of legalization by the states does offer significant opportunities for the US Department of Agriculture, Environmental Protection Agency (EPA), National Institutes of Health (NIH, and Occupational Safety and Health Administration (OSHA) to fund research into legal to protect the environment.

"Generating accurate data in all the areas we discussed offers significant potential to reduce energy consumption and environmental harm, protect public health and ultimately, improve cultivation methods," said Dr Vizuete . "There are also significant potential issues caused by emissions from the plants themselves rather than smoking it. These emissions cause both indoor and outdoor air pollution."

Explore further

Changing the federal legal status of marijuana could boost research, ease confusion

More information: K. Ashworth et al. High Time to Assess the Environmental Impacts of Cannabis Cultivation, Environmental Science & Technology (2017). DOI: 10.1021/acs.est.6b06343
Citation: Legal marijuana sales creating escalating damage to the environment (2017, February 21) retrieved 26 August 2019 from
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Feb 21, 2017
"There are also significant potential public health issues caused by emissions from the plants themselves rather than smoking it. These emissions cause both indoor and outdoor air pollution."

What the hell? Is this seriously claiming that cannabis plants emit pollutants? What a garbage anti-weed propaganda hatchet job.

Feb 21, 2017
What a garbage anti-weed propaganda hatchet job.

The paper referred to above is actually quite pragmatic - about Volatile Organic Compounds (VOCs) they say research is required to "identify opportunities for reducing emissions." About the environmental impacts of industrial scale cannabiculture they say there is an urgent need for:
"...identifying the opportunities to mitigate such impacts, and developing a framework of stewardship worthy of a modern progressive industry."

VOCs from many sources are a serious problem in air pollution. Terpene derivatives given off by smelly plants are particularly reactive. Pine trees are well-studied for their contribution to air pollution especially when the VOCs (or essential oils as they are called in aromatherapy) mix with other pollutants such as nitrogen oxides. The reaction products include the incredibly dangerous ozone and particulates. The WHO has advised that air fresheners add to air pollution.

Feb 21, 2017
There is nothing inherent in cannabis cultivation that causes environmental impact, especially when compared to such crops as corn, rapeseed, soybeans, etc. Illegal grows on public lands and bad agricultural practices would be the same impact for cannabis as it would be for any annual plant. Many (if not most) legal grows are indoors, using advanced techniques, and have little impact save the electricity and water they use -- both of which could be greatly reduced with solar aquaponics.

Feb 21, 2017
Nonsense, tomatoes would use more resources.

Feb 21, 2017
This is a ridiculous screed. Legal growers in California do not harm the land, they are regulated and taxed, as in Colorado, but there every plant started has its number - the regulation is too tight.

I wonder if the Tobacco South has other axes to grind than the effects of Cannabis agriculture on the land.

Feb 22, 2017
Ok... Basic science and scientific method 101 ! First of all it is well established that Hemp and Cannabis Sativa are very similar plants except that hemp contains 0% t.h.c. Hemp growing was directly suppressed after WW2 by Hurst because Hemp Clothing lasts 2x as long as cotton and Hurst Owned cotton plantations. Hurst paid the Fed to demonize Hemp and make it into a schedule 1 narcotic, even though you can not get high off it unless you smoke a whole bale, and even then you are high from smoke inhalation not THC ! Hemp is well known as a soil re-builder, and reconditions farm land. Low grade Cannabis does the same. Let's get the fact's strait. Human ignorance appears to be now becoming a priority that the science Inc. (That is Corporate hear-say) that is dogmatically asserted and insinuated into the place of actual research based science. When engineers are not allowed to do actual experiments, but must instead use only pre-generated and UN-validatable spread-sheets it's not science.

Feb 22, 2017
It is well established agricultural fact that Hemp and Cannabis Rebuild damaged soils ! And are known to help humans detoxify if taken via diet in raw drinks. They have powerful and proven detoxification properties. This is under attack by the chemical pharmaceutical industry, which seeks to suppress and pervert all science that does not submit to their profit motives. Scientific fact does not support business profit motives, thus Business seeks to establish Dogmatic fallacy in the stead of Scientific Method. This is what the Globalists seek to establish via the Green party agenda's. The green party's color stand for the color of money, and not the color of living plants. They refer to their glorification of GREED.

Feb 22, 2017
William Randolph Hurst has caused immense damage to American Agricultural potential, and has used his immense ill-begotten wealth to establish ridiculous unscientific and outright Machiavellian laws intended to build his cotton empire at any cost to human kind. The cost was severe enough, that under constitutional law Hurst is legally definable as being fully guilty of Treason against the United States. He has violated the Unalienable rights of countless Americans who his estate now owes full reparations to for his crimes against humanity and his crimes against science. Science is not, and must never be allowed to become a corporate tool of subjugation and mental enslavement, or for the enhancement and magnification of corporate domination of humanity so as to deny thinking reasoning human being of the truth of science.

Feb 22, 2017
Oh for feks sake! Terpines as a VOC pollutant to the environment? What the hell are you smoking? Have you walked through a pine forest recently? Now let's talk about terpines in the environment! As for water usage, lets talk intensiveness of the agricultural practises, how much bang for your buck so to speak. Let's face it, it's not broad acre agriculture like cotton that needs water and pesticides in industrial scales. It's a niche industry!

Sorry I missed the underlying point to the article...'somebody think of the children!'

Feb 22, 2017
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Feb 22, 2017
"Researchers ... have called on U.S. federal agencies to fund studies that will gather essential environmental data from the legal cultivation farms and facilities."

No reason the environmentalists shouldn't get in on the cannabis gravy train, too. No study too ridiculous. All aboard!

You can tell that Science has become a Religion: absolute faith in absurdity, and questioning is heresy. But isn't it patently absurd to suppose that growing one sort of herb is remarkably different from growing another? Anyone seen urgent funding requests to study the sustainability of rosemary farming? Or tobacco, for that matter?

Feb 22, 2017
You can tell that Science has become a Religion: absolute faith in absurdity, and questioning is heresy. But isn't it patently absurd to suppose that growing one sort of herb is remarkably different from growing another? Anyone seen urgent funding requests to study the sustainability of rosemary farming? Or tobacco, for that matter?

One could also think that every planet and star is alike but because of science we know it is not so. It may seem absurd to study some things but I think it's better to overstudy than make predictions. You don't think sustainability of tobacco farming hasn't been researched? I got 105k hits on google scholar. You know why they aren't focusing on rosemary farming? It's not one of the fasterst growing markets in the world.

Feb 22, 2017
The good dispensaries in California test for both herbicide/pesticide residue and potency.

I found dilute isopropyl alcohol does it for pests, then evaporates. I do not grow cannabis but this works on all other plants.

Feb 22, 2017
Yeah, it takes a lot of water and electricity to have a plantation. But so what? They pay for those.

Feb 22, 2017
It's interesting the title is legal marijuana sales, but the gist of the article is about illegal growth and harvest. It does appear this is written by someone with an agenda, i.e., let's spread misinformation about this evil scourge upon society.

As far as William Randolph Hearst having a hand in the demonization of cannabis I had never heard that before. I had long been under the impression it was mostly companies like Weyerhauser and other paper product companies who wanted to protect their products and profits the way General Motors and their cartel did with public transportation.

The way pretty much anything is grown on a large scale these days there numerous chemicals being used, bad irrigation practices used, soil loss being generated on large scales , etc. I find it essentially impossible to view this article as being purposefully generated to cause consternation regarding growing cannabis.

Feb 22, 2017
You do not want large commercial growers in this business. Now we have dedicated users doing this and making sure it is as pure as they can get it. After seeing what "Agribusiness" did to the Central Valley of California, we must fight to keep them out of it.

Feb 22, 2017
I see a chronic malcontent has his rage-bot voting all my posts down, in his adolescent attempt to hurt others. Do these folk not understand it says more about them than about me?

Feb 22, 2017
" studies..." There ya go, follow the money...

Feb 22, 2017
Why would szore assume scientists have the ethics of businessmen, who exaggerate, fib, and promise whatever it it takes to make the sale?

Do the actions of Trump not show him the differences, the lies versus proofs, the boasts versus facts, the inability to see reality and prove it, like is demanded in science?

Feb 22, 2017
"the increased cultivation and sale of this crop also creating escalating environmental damage and a threat to public health?"

-This is funny given that every open body of water in kansas is polluted from cattle farm runoff.

Feb 22, 2017
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Feb 22, 2017
Frosted Flake, when you say Neem oil is non-toxic are you discounting the human fatalities for some reason? Several cases of multiple fatalities in children are described in: Mishra A, Dave N. Neem oil poisoning: Case report of an adult with toxic encephalopathy. Indian J Crit Care Med [serial online] 2013 [cited 2017 Feb 22];17:321-2. Available from their website.

As far as I know the safety of smoking material treated with Neem has never been studied.

Neem oil is also known to be highly toxic to fish and other aquatic organisms.

I think the problem with the present illegal industry switching over to legal is that many of the growers will be clinging to their trusted methods of growing that they learnt while it was illegal. Unfortunately, a lot of those methods are based in hearsay, superstition, biased marketing by nutrient companies and needless waste. I would recommend that those commenters who have not read the paper referred to in the article do so now.

Feb 23, 2017
Frosted Flake - the link is http://www.ijccm....t=Mishra

The NPIC reference you give includes the remark "In other countries, neem oil has been used on cats for flea control. [...] Some of the cats died. However, most of them recovered within 1 to 5 days." This is despite the author going on to say "Neem oil is practically non-toxic to birds, mammals, bees and plants."

I am luckily devoid of experience in neem poisoning. I did not realise we were encouraged to put links on here. I do know that googling the title of a paper will usually find it, using Google Scholar if it is not easy to find with the main search engine.

Feb 23, 2017
Frosted Flake, you might find this paper of interest, as well. Bumblebees are not deterred from feeding even on neem-tainted nectar and pollen with many times the lethal concentration. Barbosa, W.F.,
De Meyer, L., Guedes, R. N. C. & Smagghe, G. (2015) Lethal and sublethal effects of azadirachtin on the bumblebee Bombus terrestris (Hymenoptera: Apidae). Ecotoxicology
24:130–142. http://pub.jki.bu...348/5093

The lack of any testing of the toxicity of neem-treated plant material when smoked is still a very relevant factor when considering recommending neem as a panacea for growing sustainable cannabis.

Feb 24, 2017
Why not grow in data centres? Imagine this:
-A metamaterial is made that emits the correct spectra for the plant when heated
-This material is used as a heatsink on the servers
-The plants are downwind of the servers, getting hot air and radiation
-Exhaust is fed to a natural gas power plant, converting all the VOCs to CO2
-Water used on the plants also cools the servers

Not sure how I thought of this. Must be a by-product of smoke inhalation.

Feb 26, 2017
Frosted Flake, did you not read the discussion section in the IJCCM paper?
"..., in a case series of 12 children with neem oil poisoning ... reported fatality in 10 cases with features of toxic encephalopathy and metabolic acidosis. ...reported Reyes-like syndrome in fatal cases of Neem oil poisoning in a case series of 13 children."
Kills children does not equal non-toxic to me. Perhaps it does not have more subtle toxicity at lower doses but that should not be assumed. Worker safety measures should apply as for other pesticides.
Bee studies are the way to test toxicity to bees. If you have real concerns that they "broke every rule" contact the The International Commission for Plant-Pollinator Relationships Bee Protection Group who published it. Neem poison stops bees eating even at very low levels so yes, the effects were from "starvation".

If California organic farmers are worsening CCD by using neem we need to know now.

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