[SkyHighLer]

^ Thank you.

Is further elaboration necessary??

The butane residual 'standards' are derived from an apple and orange comparison. The dilution factor is completely ignored in both the toxicity and odor threshold calculations.

Figure in the dilution factor, or do a straight test by capturing in a bag a dab that has been vaporized and diluted with a lungs worth of air, and then analyzing the contents for butane levels in ppm.

No matter the ppm level of butane in a dab, until it is released it can be neither odorous or toxic; and imo when vaporized and diluted with air, it is still neither odorous or toxic.

[SkyHighLer]

Originally Posted by Gray Wolf

Butane is a subtle odor and taste, so as noted is easily masked by the unsubtle monoterpenes. It's more detectable extracting old material mostly devoid of the competing aromatic odors and flavors.

Here is a link showing sensory thresholds for different solvents when isolated. https://cschi.cz/odour/files/world/M...g%20Method.pdf

It shows butane and propane at 1200 and 1500 PPM/VV for odor.

As a GRAS solvent with an FDA 5000 ppm residual standard, and such a high odor sensory cutoff, the issue is taste rather than toxicity and odor.

Our sense of taste is more refined, but sorting out the butane flavor from the monoterpenes below 500 ppm is a challenge for me, and our cotton candy concentrates typically test below 300 ppm after about 4 1/2 to 5 hours under vacuum at ~115F, with a couple flips.

Attached is "Table 2 Odor thresholds measured by the triangle odor bag method (ppm,v/v)" from the link GW provided.

https://cschi.cz/odour/files/world/M...g%20Method.pdf

[SkyHighLer]

At sea level and at 15°C air has a density of approximately 1.225 kg/m3
https://en.wikipedia.org/wiki/Density_of_air

One cubic meter equals 1000 liters
https://www.metric-conversions.org/v...-to-liters.htm

The average total lung capacity of an adult human male is about 6 litres of air.
https://en.wikipedia.org/wiki/Lung_volumes
(For convenience and to be conservative I’ll be assuming in my calculation only a single liter of dilution.)

A residual level of 5,000 ppm is .005 of a gram of butane in a gram of BHO. A tenth of a gram dab would contain .0005 of a gram of butane.
(decimal point > tenths > hundredths > thousandths > ten-thousandths > hundred- thousandths > millionths)
https://www.icmag.com/ic/showpost.ph...66&postcount=3


Conversion of kilograms of air to grams: 1.225kg x 1,000g/kg = 1,225g

Weight of a cubic meter of air factored to the weight of a single liter: 1,225g/m3 x m3/1,000L = 1.225g/L

Weight of a liter of air and a tenth of a gram dab: 1.225g + .1g = 1.325g

Butane residue proportion: .0005g/1.325g = .000377 = 377 ppm


A tenth of a gram dab containing a butane residue of 5,000 ppm presents only several hundred ppm of butane when consumed as intended.


The table GW provided indicates an odor threshold of 1,200 ppm for butane.

https://www.icmag.com/ic/showpost.ph...2&postcount=12


No odor, no toxicity.

[SkyHighLer]

When you get your head around the above, do the math for the other residual solvents, here's an interesting example, benzene. Benzene should be limited to 2 ppm before dilution due to possible oral ingestion toxicity, the second calculation is to show how high a ppm of benzene you could have in your oil and still have only 2 ppm in the diluted vapor.

At sea level and at 15°C air has a density of approximately 1.225 kg/m3
https://en.wikipedia.org/wiki/Density_of_air

One cubic meter equals 1000 liters
https://www.metric-conversions.org/v...-to-liters.htm

The average total lung capacity of an adult human male is about 6 litres of air.
https://en.wikipedia.org/wiki/Lung_volumes
(For convenience and to be conservative I’ll be assuming in my calculation only a single liter of dilution.)

A residual level of 2 ppm is .000002 of a gram of benzene in a gram of BHO. A tenth of a gram dab would contain .0000002 of a gram of benzene.
(decimal point > tenths > hundredths > thousandths > ten-thousandths > hundred- thousandths > millionths)

Conversion of kilograms of air to grams: 1.225kg x 1,000g/kg = 1,225g

Weight of a cubic meter of air factored to the weight of a single liter: 1,225g/m3 x m3/1,000L = 1.225 g/L

Total weight: 1.225 + .1g = 1.325g

Benzene residue proportion: .0000002g/1.325g = .00000015094 = .151 ppm

13.25 proportion (dab ppm to dilute ppm)



Here's the second example showing even with an unacceptable level of benzene in your oil, when diluted with air during vaporization the ppm level becomes acceptable.

A residual level of 26.5 ppm is .0000265 of a gram of benzene in a gram of BHO. A tenth of a gram dab would contain .00000265 of a gram of benzene.

Benzene residue proportion: .00000265g/1.325g = .000002 = 2 ppm

13.25 proportion (dab ppm to dilute ppm)


The FDA USP <467> Residual Solvent guidelines limit benzene to 2 ppm.

https://www.fda.gov/downloads/drugs/.../ucm073395.pdf


If you assume a tenth of a gram dab, and a one liter dilution factor, the ppm of the original dab versus the diluted ppm is a factor of about 13.25 times.

[SkyHighLer]

Not a critical thinker in the house.


Links to the testing labs, and a few blogs. Not a word explaining why a ppm limit for direct bodily ingestion (the FDA USP <467> Residual Solvent Guidelines) is referenced for a substance that is highly diluted by the delivery system before ingestion.

https://www.leafly.com/news/industry...s-concentrates

https://www.sclabs.com/residual-solvent-testing/

https://www.steephill.com/blogs/33/W...lvent-Analysis

https://analytical360.com/#services

https://www.moderncanna.com/cannabis...idual-solvent/

https://www.nordicanalytic.com/?page_id=67

https://digipathlabs.com/inherent-re...ents-cannabis/

https://www.analyticalcannabis.com/a...xtracts-289021

https://potguide.com/guides/cannabis-concentrate-guide/

https://hightimes.com/grow/concentra...tractions-101/

[SkyHighLer]

Several states have widely varying concentrate residual standards, all created by accredited authorities, none of whom mention the only real health concern is the actual ppm exposure.


I have suggestions for common sense fact based residual standards, or you can go on throwing the baby out with the bathwater (or you can go on purging the terpenes out with the solvent.)

[SkyHighLer]

With the above posts as my basis, below is my recommendation for revised cannabis concentrate residual standards.


Utilize verbatim the ppm limits of FDA Q3C — Tables and List Guidance for Industry. (Propane and butane though not listed are Class 3.)


My only request is that a note be attached to the concentrate residual standards explaining how this offers ample protection if orally ingested, and that the ppm of the solvent residuals is reduced by a factor of ten times or more when diluted with air during vaporization.

https://www.fda.gov/downloads/drugs/.../ucm073395.pdf



FDA Q3C — Tables and List Guidance for Industry

III. SOLVENTS GROUPED BY CLASS

Solvents in Class 1 (Table 1) should not be employed in the manufacture of drug substances, excipients, and drug products because of their unacceptable toxicity or their deleterious environmental effect. However, if their use is unavoidable in order to produce a drug product with a significant therapeutic advance, then their levels should be restricted as shown in Table 1, unless otherwise justified. The solvent 1,1,1-Trichloroethane is included in Table 1 because it is an environmental hazard. The stated limit of 1,500 ppm is based on a review of the safety data.

Table 1. – Class 1 Solvents in Pharmaceutical Products (Solvents That Should Be Avoided)

Solvent/Concentration Limit (ppm)/Concern

Benzene/2ppm/Carcinogen

Carbon tetrachloride/4ppm/Toxic and environmental hazard

1,2-Dichloroethane/5ppm/Toxic

1,1-Dichloroethene/8ppm/Toxic

1,1,1-Trichloroethane/1,500ppm/Environmental hazard



Solvents in Class 2 (Table 2) should be limited in pharmaceutical products because of their inherent toxicity. PDEs are given to the nearest 0.1 mg/day, and concentrations are given to the nearest 10 ppm. The stated values do not reflect the necessary analytical precision of determination. Precision should be determined as part of the validation of the method.

Table 2. – Class 2 Solvents in Pharmaceutical Products

Solvent/PDE (mg/day)/Concentration Limit (ppm)

Acetonitrile/4.1mg/410ppm

Chlorobenzene/3.6mg/360ppm

Chloroform/0.6mg/60ppm

Cyclohexane/38.8mg/3,880ppm

Cumene/0.7mg/70ppm

1,2-Dichloroethene/18.7mg/1,870

Dichloromethane/6.0mg/600ppm

1,2-Dimethoxyethane/1.0mg/100ppm

N,N-Dimethylacetamide/10.9mg/1,090ppm

N,N-Dimethylformamide/8.8mg/880ppm

1,4-Dioxane/3.8mg/380ppm

2-Ethoxyethanol/1.6mg/160ppm

Ethyleneglycol/6.2mg/620ppm

Formamide/2.2mg/220ppm

Hexane/2.9mg/290ppm

Methanol/30.0mg/3,000ppm

2-Methoxyethanol/0.5mg/50ppm

Methyl butyl ketone (MBK)/0.5mg/50ppm

Methylcyclohexane/11.8mg/1,180ppm

Methyl isobutyl ketone (MIBK)/45mg/4,500ppm

N-Methylpyrrolidone/5.3mg/530ppm

Nitromethane/0.5mg/50ppm

Pyridine/2.0mg/200ppm

Sulfolane/1.6mg/160ppm

Tetrahydrofuran/7.2mg/720ppm

Tetralin/1.0mg/100ppm

Toluene/8.9mg/890ppm

1,1,2-Trichloroethene/0.8mg/80ppm

Xylene/21.7mg/2,170ppm



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. It is considered that amounts of these residual solvents of 50 mg per day or less (corresponding to 5,000 ppm or 0.5 percent under Option 1) would be acceptable without justification. Higher amounts may also be acceptable provided they are realistic in relation to manufacturing capability and good manufacturing practice (GMP).

Table 3. – Class 3 Solvents Which Should Be Limited by GMP or Other Quality-Based Requirements

Acetic acid

Acetone

Anisole

1-Butanol

2-Butanol

Butyl acetate

tert-Butylmethyl ether

Dimethylsulfoxide

Ethanol

Ethyl acetate

Ethyl ether

Ethyl formate

Formic acid

Heptane

Isobutyl acetate

Isopropyl acetate

Methyl acetate

3-Methyl-1-butanol

Methyl ethyl ketone (MEK)

2-Methyl-1-propanol

Pentane

1-Pentanol

1-Propanol

2-Propanol (isopropyl alchohol)

Propyl acetate

Triethylamine

[SkyHighLer]

^ I just came across the FDA draft on Class 3 residual solvent limits, they've already factored in huge toxicological safety margins.


APPENDIX 6. TOXICOLOGICAL DATA FOR CLASS 3 SOLVENTS

https://www.fda.gov/downloads/drugs/.../ucm073403.pdf

[SkyHighLer]

The dilution factor I used was based on a full tenth of a gram dab (theoretically assuming no reclaim fallout,) and a liter of air.

I realize there are those who supposedly take gram dabs, but I doubt they dilute it with less than a liter of air. My assumption is nearly everyone dabs in the .05 to .2 gram range with a tenth of a gram being a huge dab for most.

The one liter air dilution factor I used was tested by inflating and deflating a quart zip-lock bag with my breath. In the pictures you can see how a quart bag looks when filled with a liter of water, and how it looks inflated by a straw I inserted for the test. I take my dabs with about three quarters of a liter to a liter and a half of air.

[SkyHighLer]

^^^^^^^^^^ There's my rebuttal to claims of tasting or being poisoned by butane residuals.