Cannabis Extraction Solvent Safety

CANNABIS EXTRACTION SOLVENT SAFETY - AN EVIDENCE BASED REVIEW

INTRODUCTION

On January 12th 2024, this page was presented as a talk and slideshow to EduCannation members for a look at solvent safety in the home. Fortunately for you, this has been edited down. The revised slideshow is available via this link if you'd like to peruse it for the hotlinks to the references. There are author notes at the bottom of each slide via a pull-up handlebar. 

Right upfront, I need to say, I am not a medical doctor, nor medical professional, just an avid cannabis enthusiast. Nothing you hear in this presentation should be taken as medical advice. My presentation today is a review of solvents at the residual trace level by reviewing existing government regulations, medical studies, and chemical properties of solvents.

Solvent Wars

Today, we will look at how to safely make cannabis oil at home, but first must address the elephant in the room. There is a debate in the consumer world around which solvents are appropriate for home extraction. This debate pits Ethanol against Isopropyl Alcohol with claims that the former is harmless because you can drink it, and the latter, Isopropyl Alcohol, is poisonous in any quantity.

A claim that Ethanol is safe because it has a Generally Regarded As Safe (GRAS) rating, ignores the fact that Isopropyl and Acetone also have a Conditional GRAS rating for presence in certain food additives. Here’s the reality - Ethanol metabolizes into a known carcinogenic that may damage the body with every drink. This damage comes in very small amounts that accumulate into long term adverse health issues such as Cirrhosis of the Liver, Fatty Liver Disease, cancer, birth defects, and DNA damage. These are real consequences the general public ignores for the momentary pleasurable effects of intoxication. The World Health Organization has published a paper “No amount of alcohol is safe for consumption”.

Turning to Isopropyl, the problem with arguments against IPA, these are always centered on drinking quantities. Those making that argument are missing the most obvious fact - you will never encounter drinking quantities of any solvent when ingesting oil concentrates. As we will see graphically, this is physically impossible. Some medical patients may ingest up to a gram of oil per day with residual traces a mere fraction of that weight. As we will see, government regulations have set daily exposure limits for every solvent.

Consumers in general are completely naive regarding the governing regulations on residual solvents. Decades ago, the FDA published Permitted Daily Exposure (PDE) values of each solvent. It comes as a complete surprise that Acetone actually has a higher PDE value than Ethanol. This hints at a completely different narrative than what consumers have come to believe. A vast majority of consumers never depart from childhood learning where our parents tell us ‘Don’t Drink that, it’s poison!’. That served us well as children, but as adults having access to a world of information at our fingertips, we can easily find the truth about how residual solvents affect our bodies. 

The reality is, you should never drink solvents, except of course water, which is the most polar solvent on earth. This presentation takes the reader to a deeper level of understanding around solvents with the use of illustrations to drive the point home - residual traces that fall under the FDA’s Permitted Daily Exposure values are harmless, even for popular Ethanol that is the most damaging of the four solvents.

TABLE OF CONTENTS

Today’s presentation is based on a revised slide show to an earlier talk. You are encouraged to view the slides as they are packed with hyperlinks to all references. The final slide has a link to a PDF containing all the references and more.Finally, you'll find the author slide notes via a pull-up bar at the bottom of each slide.

                           

METABOLISM OF SOLVENTS


The first thing we want to do is review the body’s metabolism of the solvents. Of the four solvents discussed today, these form two groups based upon the body’s metabolism. Ethanol and Ethyl Acetate form one group, with Isopropyl and Acetone forming the second. It is crucial to understand how these two solvent groups are processed by the human body.

First, lets look at Ethanol. Ethanol is broken down by the liver and kidneys to form a known carcinogen called Acetaldehyde.

Figure 1: Slide 3

Acetaldehyde is considered a reactive oxygen species (ROS) or free radical species, which is why it damages cells leading to long term health effects. It takes moderate to heavy drinking to accumulate enough damage to lead to serious long term health effects. Short term ill effects are hangovers and facial flushing.

Here is what Claude.AI says about it:

Acetaldehyde is considered a reactive oxygen species (ROS) or free radical species due to its unpaired electron structure. The term used to describe this chemical property of acetaldehyde is that it is a "reactive electrophilic compound" or "electrophilic species".

Some key points about acetaldehyde's electrophilic nature:

So in summary, the appropriate term highlighting acetaldehyde's free radical activity and electron-deficient reactivity towards biomolecules is categorizing it as an "electrophilic species" or "reactive electrophilic compound."

Now lets look at the second group which is includes Isopropyl Alcohol and Acetone. As you can see in the slide below, Isopropyl breaks down into Acetone, the simplest ketone. Acetone is not broken down any further. 

Figure 2: Slide 4

Acetone is actually generated by the liver when metabolizing fats and is used as an alternate energy source during low blood sugar levels. The sweet breath diabetics experience in low blood sugar states is excess acetone being expelled via the lungs. This is why service dogs can alert their patient to a low blood sugar state.

Best news is, with 100 years of world-wide medical and chemistry knowledge, Acetone and Isopropyl have never been found to be genotoxic, carcinogenic or teragenic, ie, does not damage DNA, cause cancer or birth defects.

One argument against Acetone and Isopropyl, is that both do not carry the FDA's GRAS rating. Turns out, yes they do, but with a limited scope of being used in preparing certain food ingredients. So, less general, more specific in what I called a ‘Conditional GRAS’ approval rating. In the previous talk, I described this as a 'Semi-GRAS' rating. 



UNDERSTANDING DRINKING VS TRACE QUANTITIES

Next, we're going to look closely at trace quantities. The FDA has published a number everyone concerned about solvents needs to understand. This number is called the 'Permitted Daily Exposure' (PDE). It is essentially a line drawn in the sand where harmless traces cross over into levels of potentially adverse effects. This number is a product of a larger calculation taking into consideration multiple factors.

In the table below are the relevant chemical properties of the solvents. I am highlighting two columns showing the FDA’s Permitted Daily Exposure (PDE) values. 

Figure 3: Slide 5          Click the hotlinks to view the reference data.

In the left column, the numbers are per kilogram of body weight, per day. The right hand column is the value multiplied out for a 105lbs person. As you can see, Acetone actually has a higher PDE than Ethanol.

This is significant because Acetone in trace amounts is being recognized as being less harmful than Ethanol. Of course, just like stomach acid, larger volumes take on harsher characteristics.  Higher production means it can dissolve more, but the higher volume may spill over causing ulcers. Same with Isopropyl and Acetone where higher volumes cause gastric distress. At drinking volumes, Isopropyl will get you more inebriated than Ethanol with much more discomfort and pain. Every health clinic around the world has an Alcohol Overdose protocol that includes Isopropyl because this is a world wide problem. 

Ethanol, Isopropyl and Acetone in 90+ concentration are not for drinking. These are solvents sharing very similar molecular structure and similar chemical characteristics. If you drink it, it will hurt you. Did you know Acetone, sold as finger nail polish remover, is sold with a bittering agent to keep you from drinking it? No need for a bittering agent in Isopropyl because in volume, its a real punch in the gut. Both Acetone and Isopropyl toxicity will make you miserable. Ethanol plays the game differently by being both toxic (toxic effects include central nervous system depression) and then metabolizing into a carcinogen that leads to long term adverse health effects. 

Back to measuring residual traces, the foundation of the FDA’s PDE number is based upon the chemical property called Limit of Quantification (LOQ). Look familar? This term is commonly used in Cannabis Potency lab tests. LOQ quantities are the smallest amount of the chemical that can be reliably measured thus used as a baseline value in the FDA’s PDE calculation. There’s a lower threshold called Limit of Detection (LOD) but that’s where things get murky. The quantity is so low that detection is unreliable, something like: Did you see it? No, oh wait, there it is. Ah its gone..

Authors Postscript:   (04-21-2024)


So what happens to chemicals below PDE? During a recent conversation, a Doctor in pharmacology said this:


"I'm sure you've heard the saying "The dose makes the poison" but also the ROUTE plays a big role...how much can get in at one time? What happens when it gets there?


Yes, my point before was that LD50s are based on *animal* experiments, and PDEs are compiled from information from animal experiments with various substances as well as numbers gleaned from intended or unintended human exposures (like suicides and accidents). The estimates are estimates and they are all we have. We shouldn't worry about 50mcg of solvent in a gummy....but we also can't say with scientific certainty that it is SAFE. But we can say it's far, far below the levels that we know can cause acute harm."


To their point, when levels drop below measurability, we depend on modeling to predict the resulting chemistry. So knowing the metabolic pathway of the solvent then becomes crucial in predicting that outcome. We know Acetaldehyde is a 'Reactive Oxygen Species' that has the potential to continue damage at scale but at extremely low levels where the damaging effects cannot be observed. 

In this illustration, you can see down at the bottom of the flask, Acetone's PDE is a dividing line between trace quantities and drinking quantities for Acetone. The illustration takes this all the way up to show the estimated Lethal Dose for each solvent.

Figure 4: Slide 6

Acetone in volume has more harmful qualities in volume compared to Ethanol, leading to a lower Lethal Dose (LD50) than Ethanol. True for Isopropyl as well. The least harmful solvent in drinking quantities is Ethyl-Acetate. To the point, this illustration serves to show how close the three main solvents are in lethal volume.

Looking at the next slide, we'll focus on some real world numbers in cannabis extracts. As long as the residual solvents fall within legal limits, these numbers tell the whole story.  The solvent PDE values are show in light blue, but scaled to show a really big number. Acetone is 9.996g shown as 9,996,000 so you can compare it to the residual solvent limit established by the FDA.

In this slide, a question is posed: If a gummy has 10mg of cannabis concentrate, how much residual solvent is permitted in that 10mg?

Figure 5: Slide 7

Answer – 0.5% of 10mg is 0.05mg. This is the legal limit for residual solvent in a 10mg gummy. As you can see, that is 5 orders of magnitude below each solvent’s PDE.  

So, let me ask. How many 10mg gummies do you have to eat per hour to reach the daily PDE for Ethanol?

Figure 6: Slide 8

A crushing 6584 per hour! Bring a backhoe! It takes 65 grams of cannabis concentrate to hold 1/24th amount of residual solvent. Now multiply that by 24! You would have to eat 1,560 grams of concentrate to reach the full Permitted Daily Exposure of that residual solvent.


Bringing It Home

Can you see how ludicrous the contentious debate is over using Ethanol vs Isopropyl? It’s laughable that proponents of Ethanol argue you must exclusively use it for safety when it’s the most damaging solvent in the group at the molecular level. No, you can not drink these solvents, but that’s not a valid safety argument. Yes, you can drink diluted Ethanol, but risk cellular damage while enjoying the intoxication.

Here are the facts:

RELEVANT MEDICAL ISSUES SURROUND SOLVENTS

Moving on, lets take a look at who potentially has the greatest sensitivity to residual solvents.

Figure 7: Slide 9

Anyone with these conditions is encouraged to discuss their choosen solvent with their medical team toxicologist. Even though low trace levels are present at the gram level, some patients may have heightened reactions due to these conditions. Given there are two groups of solvents with markedly different metabolisms, this provides a choice to the patient as to which solvent may be more bio-friendly to their condition. Again, this premise must be discussed with the patient and their medical team’s toxicologist.

WHICH SOLVENTS ARE SAFE AT HOME

The FDA classifies solvents based on safety. The only safe solvents for use in the home are Class 3 solvents:

Solvents in Class 3 (Table 3) may be regarded as less toxic and of lower risk to human health. Class 3 includes no solvent known as a human health hazard at levels normally accepted in pharmaceuticals. However, there are no long-term toxicity or carcinogenicity studies for many of the solvents in Class 3. Available data indicate that they are less toxic in acute or short-term studies and negative in genotoxicity studies.“

Figure 8: Slide 10

Gasses such as Butane, Propane, and C02 are restricted from home use, only permitted in licensed facilities, requiring additional hardware and training.

So which is the most appropriate solvent for use in the home?

- All four are found in every day used products within the home. Ethanol is found in distilled spirits, beer and wine. Isopropyl may be contained in certain food ingredients, rubbing alcohol and hand gels. Acetone is sold in 99.9% concentration as fingernail polish remover. Interesting fact, here in the US, Acetone is normally denatured with denatonium benzoate, a bitterant so you don’t drink it. Ever thought you could? You don’t want to try.. Ethyl Acetate is the odd ball but is used to decaffeinate coffee and is naturally present in wine.

- All four solvents have FDA GRAS or Conditional GRAS classifications. Ethanol has the GRAS rating, whereas IPA, Acetone and Ethyl Acetate have been granted a limited use in food ingredients giving these solvents a Conditional GRAS rating.

So with all medical issues aside, the solvent selection basically comes down to economics. Any of these four solvents can safely be used without potential health issues when abiding by proper safeguards. You can have peace of mind knowing that as long as the final product falls within the FDA’s Permitted Daily Exposure limits, the risks are negligible at worst, non-existent at best.

And the recommendation? - Isopropyl Alcohol

Figure 9: Slide 12

For home use, Cannabis Home Sciences recommends Isopropyl Alcohol as the best solvent for cannabis extraction. With the metabolic pathway of Isopropyl now known (that it converts to acetone and used as energy or expelled), you can have peace of mind that Isopropyl is not the boogie man your parents warned you about. They were right one way, you don't want to drink it, it will kick your a...

Here in the United States, Isopropyl Alcohol is most cost effective solvent given the government taxes ethanol sales to fund itself. But down in South Africa, Acetone is apparently easier and cheaper to acquire than either Ethanol or Isopropyl.

So, with all we’ve now covered, it becomes obvious the argument to exclusively use Ethanol for making cannabis oil ‘because you can drink it’, or that only Ethanol has a GRAS rating, is incorrect. In reality, such position actually hurts the financially disadvantaged. Medical patients are being cowed into use costly solvents just for the arguer’s convictions, not based on facts or science. 

Figure 10: Slide 13

Looking closer, Isopropyl’s chemistry has a slight advantage over ethanol as see in the Solvent Properties table in Slide 5. It’s about 20% less polar than Ethanol making it more focused on what we want to target. One study determined Isopropyl extracts more cannabinoids that Ethanol.

One widely published stat about Ethanol is that it become less polar at colder temps. Just to clarify, this is a law of physics applicable to all solvents. As heat energy is reduced, the effects of polarity also lowers. This is true for Isopropyl as well. The polarity drops in freezing temperatures just like Ethanol’s.

At -18c/0f, Isopropyl is viscous as Ethanol and has a near matching boiling point. Both Ethanol and Isopropyl have a 30 degree lower boiling point than water which means Isopropyl is just as easy to boil out and recover as Ethanol. Acetone is 30 degrees lower than that which makes it possibly the best solvent for saving the acidic states.

Ethyl Acetate is an ester of Ethanol and Acetate. Acetate is an ionized version of Acetic Acid, aka, vinegar. Ethyl Acetate is not a common solvent at retail so it’s price is a stratified as it is rare. The down side is, this is a single-use solvent. Ethyl Acetate will breakdown into it’s components of Ethanol and Acetic Acid in water during the first reduction when making RxCE oil. Acetic Acid will continue to dissolve in water to form acetate so there’s not an isomerization issue.


Guidelines for Purchasing Solvents at Retail

Here are some guidelines for qualifying the solvents bought at retail. Once you find a vendor of solvents, make sure the product is not denatured and has a GRAS or Conditional GRAS rating. Every solvent is sold in various grades. Denatured products should be avoided, only use medical grades or higher. Slide 17 lists few hardware vendors with solvent recovery systems so you can reuse the solvents.

TIP: Be aware 99.9% Ethanol or Isopropyl will absorb any water content and settle into 95% or 91% concentration respectively. This makes the only effective use of 99.9%+ solvents on room temperature dried plant material. Any frost on frozen plant material will add water negating the benefit of the dehydrated alcohol.

Figure 11: Slide 14

WHAT PROCESSES ARE SAFE TO MAKE OIL AT HOME

Just for fun with a small plug for RxCE, here is the history of cannabis oil. Cannabis history dates back to 10,000 years BC, but the extraction by solvents, either alcohol or carrier oil, is a fairly recent development dating back to the 1800s.

Figure 12: Slide 15

Figure 13: Slide 16

I bring this up to recognize how cannabis oil came about in recent times. California led the way by legalizing medical use back in 1995, but it was Rick Simpson who did the most to popularize cannabis oil. with a built-in government as an arch enemy, the story becomes a great movie script replaying yet another version of David and Goliath.

It is well known in the medical community that the Goliath repression cannabis is untruthful and unjust. Many lives have been negatively impacted, worse ruined, by the political ambitions of those in government who outlawed marijuana for political ends. Cannabis has been in medical use for millennia and it’s application is huge! Cannabis has now been documented to kill cancer cells, block covid, bring relief to epileptic seizures, appetite loss, provides pain and stress relief, plus a whole lot more. Here’s an informal, but huge list of medical studies on the benefits of cannabis organized by Granny Storm Crow.

And for those looking for equipment to make oil, here are a few retail hardware and DIY solutions to be used for solvent recovery.

Figure 14: Slide 17


VAPOR DANGERS WHILE SAFELY MAKING OIL AT HOME

Now for the last safety issue – fumes! The most worrisome fumes are generated when boiling off the solvent. At room temperature, these solvent’s evaporate at very slow rates, so these airborne quantities are not normally hazardous. It’s the solvent boiling off that raises concern. In the next few slides, we will look at how much vapor is generated by boiling off one liter/quart of solvent. Here some interesting reporting on a recent vapor cloud explosion with relevant discussion on gas and liquid states.

SAFETY FIRST! When boiling off any solvent, you must take action in verifying there are no sparks or flame sources anywhere near the distillation. These fumes will settle but it only takes light disturbances to whip up invisible concentrated clouds. This makes it impossible to judge the concentration in the air. All of these solvents have low flammability around 2-15% per square meter. Fortunately, these concentrations are well above the threshold of our olfactory detection, so your nose will remind you to check for proper ventilation. 

The best way to distill safely is either recapturing the solvent or dissipating it with ample airflow, and best outdoors, never in closed rooms. Indoors has a higher risk explosive risk due to containment so make sure there’s plenty of outdoor airflow through the distillation space. Concentrations are impossible to predict, so be safe. Always distill with plenty of airflow no where near sparks or open flame.

Figure 15: Slide 18

The next two slides hold technical data on the solvents in the form of gas. The first table gives the most commonly known properties. As you can see in the second slide, all four solvent’s explosive limits are very low in percentage of volume so safety cannot be understated. Again, for safely distilling solvents, it is recommended you use a solvent recovery system. Lacking that, be safe by boiling off the solvent in well ventilated spaces, no where near sparks or open flame.

Figure 16: Slide 19

Figure 17: Slide 20

CONCLUSION

Here we’ve looked at four different solvents commonly found in the home. From a chemistry and biological perspective, these four represent the safest solvents that can be used without requiring special training or lab gear. This data reflects the current knowledge of the world medical community and might change in the future. A lot of the in-vivo solvent testing was on lab animals then extrapolated to human scale. These numbers may change with additional research but very unlikely after all this time.

On the consumer side, due to lack of in-depth understanding of chemistry, consumers believe that ethanol is the safest because it can be ingested. This seemingly logical conclusion permits users to disregard the dangers of long term exposures leading to cirrhosis of the liver, birth defects and DNA damage.

As shown in this discussion, the most feared solvents, acetone and isopropyl, viewed as poison at any level, are actually the least biologically harmful to the human body down at the trace level. By understanding these solvents at the molecular level and following through the metabolic pathways, the picture becomes clear. The most bio-friendly solvent is Acetone, being the least toxic of all four solvents at trace levels. This fact is supported by the FDA establishing higher Permitted Daily Exposures for Acetone versus Ethanol. This is significant because the definition of PDE draws a line in the sand between harmless and harmful levels.

For virtually the entire world, the debate on Ethanol vs Isopropyl safety is actually a mute point because residual traces of these FDA Class 3 solvents are low enough to be safely metabolized by healthy liver and kidneys. Ethanol's metabolite, Acetaldehyde, is broken down by the cell's mitochondria, so it's still damaging at the lowest level but at insignificant rates. When in compliance with regulations, residual solvents in edibles has been shown to be orders of magnitude under the FDA Permitted Daily limits.

Bringing it home:

In closing, when permitted by local laws, medical patients at home have good options for solvent selection. Some Chemical-Intolerant health issues might preclude certain solvents based individual sensitivities. Those suffering from impaired liver or kidney function may now choose which solvent best fit their chemical sensitivity. This premise needs to be discussed with medical professionals experts in the field of Toxicology.

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https://drive.google.com/file/d/1jQrS1qHeSFXrXrQJRUDjkukWke_30Sdr/view?usp=sharing

NJ Dept of Health SDS - Ethanol

https://drive.google.com/file/d/14Y2yLPMEOaAclikPbN5RazTckanpimES/view?usp=sharing

NJ Dept of Health SDS - Ethyl Acetate

https://drive.google.com/file/d/11FlhmevCr_ZPx4T_EwVFis50xSQAHrOP/view?usp=sharing

NJ Dept of Health SDS - Heptane

https://drive.google.com/file/d/1FLpS82CxJ4OeFnFuCi0Va5Vx1YOiMVL1/view?usp=drive_link

NJ Dept of Health SDS - Isopropyl Alcohol

https://drive.google.com/file/d/1mLLbmyMedgAX4_wahRtBuz8bkDZ8Et8D/view?usp=drive_link

NJ Dept of Health SDS - Methanol

https://drive.google.com/file/d/17vpjqUabW5K9XA8cZbjRcuSSWr3BUDDe/view?usp=drive_link

NJ Dept of Health SDS - Pentane

https://drive.google.com/file/d/16k7avQWx7EC8eRQaAzTpGNBo_xfpe3oN/view?usp=drive_link

No Observed Adverse Effect Level

https://en.wikipedia.org/wiki/No-observed-adverse-effect_level


OSHA - Occupational Safety and Health Agency

https://en.wikipedia.org/wiki/Occupational_Safety_and_Health_Administration

OSHA Hazard Classification Guidance

https://ascopubs.org/doi/full/10.1200/JCO.2017.76.1155


Permissible Exposure Limit

https://en.wikipedia.org/wiki/Permissible_exposure_limit

Permitted Daily Exposure Values: Application Considerations in Toxicological Risk Assessments

https://pubmed.ncbi.nlm.nih.gov/32794434/

PubChem Compound Summary – Acetone

https://pubchem.ncbi.nlm.nih.gov/compound/Acetone

PubChem Compound Summary – Benzene

https://pubchem.ncbi.nlm.nih.gov/compound/Benzene

PubChem Compound Summary – Methanol

https://pubchem.ncbi.nlm.nih.gov/compound/Methanol

PubChem Compound Summary – Ethanol

https://pubchem.ncbi.nlm.nih.gov/compound/ethanol

PubChem Compound Summary – Ethyl Acetate

https://pubchem.ncbi.nlm.nih.gov/compound/ethyl%20acetate

PubChem Compound Summary – Heptane

https://pubchem.ncbi.nlm.nih.gov/compound/heptane

PubChem Compound Summary – Isopropyl Alcohol

https://pubchem.ncbi.nlm.nih.gov/compound/isopropyl

PubChem Compound Summary – Pentane

https://pubchem.ncbi.nlm.nih.gov/compound/pentane


Reference Dose

https://en.wikipedia.org/wiki/Reference_dose

Refined x Cannabis Extract oil - Cannabis Home Sciences

https://www.cannabishomesciences.com/documentation/rxce-home-page

Rick Simpon Popularized making cannabis oil

https://phoenixtears.ca/

Role of Acetaldehyde in Mediating the Pharmacological and Behavioral Effects of Alcohol

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6527032/


Texas' strongest THC gummy hits the market

https://www.axios.com/local/dallas/2023/11/14/texas-original-thc-gummy-edible-medical-cannabis

The impact of extraction protocol on the chemical profile of cannabis extracts from a single cultivar

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8575894/

Threshold Dose - Wikipedia

https://en.wikipedia.org/wiki/Threshold_dose

Toxicological Profile for Acetone - CDC

https://www.atsdr.cdc.gov/toxprofiles/tp21.pdf

Toxicokinetics of organic solvents - NIH

https://pubmed.ncbi.nlm.nih.gov/3906871/

Toxicokinetics of Organic Solvents

https://www.jstor.org/stable/40965128

Tribute to Professor Raphael Mechoulam, The Founder of Cannabinoid and Endocannabinoid Research

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8746417/


WHO - World Health Organization

https://en.wikipedia.org/wiki/World_Health_Organization


GLOSSARY:

ADI: Acceptable Daily Intake: 

                        The amount of a substance that can be consumed daily over a lifetime without causing harm.

ALD: Alcoholic liver disease

CLD: Chronic liver disease

EC: Endocannabinoid

ECS: Endocannabinoid system

EC50: Effective Concentration 50%

ED50: Effective Dose 50%

LC50: Lethal Concentration 50%

LD50: Lethal Dose 50%

LEL: Lower Explosive Limit

LOAEL: Lowest Adverse Effect Level

MRL: Maximum Residue Limit

NAFLD: Non alcoholic fatty liver disease

NOAEL: No Observed Adverse Effect Level

PDE: Permitted Daily Exposure determined by EPA’s calculation based on LOAEL

PEL: Permitted Exposure Limit of chemicals via OSHA measures airborne contaminates

PNEC: Predicted No Effect Concentration: 

                        The concentration of a substance in the environment that is not expected to cause adverse 

                        effects on aquatic organisms.

PPM: Parts Per Million of one liter

        1.000,000 Liter (1kg), milliliter (1g), milligram (1mg)

PPB: Parts Per Billion of one liter

        1.000,000,000 Liter (1kg), milliliter (1g), milligram (1mg), microgram (1ug)

RfC: An estimate of a continuous inhalation exposure concentration to people

        (including sensitive subgroups) that is likely to be without risk of deleterious

        effects during a lifetime.

RfD: Reference Dose: The amount of a substance that is likely to be without risk

        of adverse health effects over a specified duration of exposure.

UEL: Upper Explosive Limit

Revision History - Cannabis Extraction Solvent Safety - An Evidence Based Review

24/04/21 Added a Author's Postscript paragraph on values below PDE.

24/03/18     First 'Release Candidate' to the FB group, then a bunch of edits..

23/11/26 First publication for proof reading

23/10/29 Page construction begins.