Reading product labels can reveal a lot of information. Some of this information involves weight and volume but doesn’t involve concentration, as in how much of the product is the actual active ingredient. By understanding the metric notations for weight and volume, you will be able to calculate the CBD concentration of each product you buy, which will allow you to have a consistent CBD dosage across a multitude of products. First, let’s look at the imperial and metric systems.
Imperial and Metric Systems
The imperial system is based on “real life” measurements that were meant to help mercantile trades be fair. It is believed that the “pound” was initially a weight hung by the cord in the royal treasury against which all other weights were measured. In the UK, a piece of silver that weighed a pound would be minted into coins, which is how they got the term “pound sterling” for money.
But why would the French ask for permission from the British to check if their weights were valid? They could make their own pounds, ounces and so forth. The Germans then made their own “pfunds” and so on. Soon enough, the word “pound” became meaningless because it differed slightly from one country to the next. For its time, the imperial system was good enough, but now we’ve got something better: the metric system.
The metric system is based on units that scale by the thousand and have a prefix that shows where on the scale it is. So, by taking a base unit, such as a liter, we can add a prefix such as milli, micro, nano or pico to denote a quantity one thousand, one million, one billion or one trillion times smaller than a liter. Conversely, we can add a prefix such as kilo, mega, giga or peta to denote a quantity larger than a liter.
The same idea applies to length, weight and so on. You will rarely hear some of these prefixes because they are normally only used by scientists, who often prefer to use numbers. However, some of these terms are seen in the public, such as milligram, which means a thousandth of a gram. When you see an expression “5 mg” on a product label, it means five-thousandth of a gram, which is so small that you can’t really measure it at home. How much is a milligram anyway?
Spoons and Cups as Scientific Measurement Tools
We most commonly use teaspoons, tablespoons and cups as measurements at home. One teaspoon is 5 grams or 5,000 milligrams, so a milligram is one five-thousandth of a teaspoon; a tablespoon is 15 grams or 15,000 milligrams; a cup is 250 milliliters or mL (also abbreviated as “ml”), which might or might not be 250 grams depending on what you’re measuring. Things can get even trickier when we realize there are imperial and U.S. teaspoon measurements. In general, all teaspoons should be 5 ml.
In practical terms, you can’t really measure a milligram at home, but you’ll rarely handle substances that need such precision. Scientific measurements are performed using precise tools that measure milliliters and milligrams, so seeing these prefixes on a product implies they were measured using precise tools. When you purchase a liquid CBD product, you’ll normally receive a dropper that’s meant to help you dose the liquid, but how can you tell how much CBD is dispensed by the dropper?
A full dropper commonly contains 1 ml of liquid, and since you’ll often be instructed to use half a dropper, that means 0.5 ml of liquid. So how much CBD is in 0.5 ml of liquid? To discover that, you need to know the concentration, and for that, you need to know the mass, expressed in milligrams, and volume, expressed in milliliters.
Concentration is Mass Divided by Volume
By dividing mass by volume, you get concentration, aka density when applied to solids. Let’s take a practical example to explain it better. 500 mg CBD oil is listed as having a 30 ml volume, so now we have the weight (500 mg) and volume (30 ml). Divide the two and you have 16.6 mg/ml. Therefore, 0.5 ml of CBD liquid contains 8.3 mg of CBD, giving you 60 equal doses per 30 ml bottle.
A bottle with 5,000 mg of CBD oil is again 30 ml, so now you can already estimate how much CBD is in it compared to the 500 mg bottle; 10 times more, with one full 1 ml dropper giving about 165-166 mg of CBD. Once you can calculate concentration, you can purchase several CBD bottles and maintain the same dose across them. So, is 8.3 mg of CBD too much? How much toxicity does CBD exhibit?
CBD Toxicity Studied on Mice
A 2019 U.S. study titled “Hepatotoxicity of a Cannabidiol-Rich Cannabis Extract in the Mouse Model” investigated what would happen to livers of mice given excessive doses of CBD. The mice were split in two groups: one that was given a high dose of CBD straight away (“acute”) and the other received medium doses over several days (“sub-acute”). The acute group received up to 2,460 mg of CBD per kilogram of body weight in 24 hours and the sub-acute group received up to 615 mg of CBD per kilogram of body weight per day over 10 days.
Scaled up to an average adult human weighing 80 kg (175 lb), this would equate to 196,800 mg or 196.8 grams, which would be nearly 40 bottles of 5,000 mg CBD oil for the acute group and 49,200 mg or 49.2 grams or nearly 10 bottles of 5,000 mg CBD oil a day for the sub-acute group. Forget about the dropper, you’d need a bucket, a funnel, and some serious dedication to ingest this much CBD. So, what happened with the mice? Did they explode or die a horrible death? Let’s check it out.
The study reported that ingesting so much CBD caused the mice to have enlarged livers and activated liver enzymes and genes that have to do with oxidative stress. Ultimately, we’re told that “CBD exhibited clear signs of hepatotoxicity”, though three-quarters of mice in the sub-acute group “developed a moribund condition”, meaning they were on the verge of death. So, the mice did survive these immense doses both when it came to taking them at once and when taking them for days.
For comparison, the maximum recommended dose for Epidiolex, the FDA-approved CBD drug for treating epileptic seizures, is 20 mg of CBD per kilogram of body weight, which would be 1,600 mg or 1.6 grams or three bottles of 500 mg quality CBD oil a day for an average adult. That’s not the entire story because testing toxicity of chemicals on mice and extrapolating the results for humans has its own issues.
Animal Model Toxicity
The study noted that the 2,460 mg and 615 mg per kilogram doses were the “mouse equivalent doses”, which is a controversial way of measuring drugs between mice and men. It seems practical but it does tend to go awry, as explained in a 2016 study from Saudi Arabia titled “A simple practice guide for dose conversion between animals and human” that states “dose conversion from animal to human studies is one of the most controversial areas in clinical pharmacology”. Not only are mice and men of different weights but have a different skin surface to weight ratio and many other differences.
It’s a practical problem—how do we measure whether a chemical is toxic to humans without giving it to humans? We’ll give it to mice and then to dogs, chicken and cows until we get an appropriate set of numbers that can be used to draw a conclusion, but it can be based on the controversial dose conversion from animal to human and back. Keep this idea of “mouse equivalent doses” in mind whenever you hear about CBD toxicity and always scrutinize the studies; there are some tricky phrases in there.
Conclusion: be an informed consumer
It’s understandable why the 2019 study may have caused concern among consumers. There’s much we don’t know about organic CBD, including its long-term liver toxicity. The authors of that study were right to suggest that we should exercise caution and aim to become informed consumers to make our own decisions. Product manufacturers can’t really make a decision on your behalf, but they can supply you with information, on all kinds of different cannabinoids so you can make your own decision.
If you are planning to buy CBD for the first time, do your research find out what to consider when shopping for CBD. Look for products that use organic ingredients, as these will help you steer clear or harmful pesticides and other toxic chemicals. You’ll also want to consider the myths vs facts about CBD products that contain extra ingredients or additives aside from CBD, terpenes, or healthy fatty acids. At buyCBDproducts.com, these are the sorts of concerns we know our customers have, so we provide third-party lab results with every product we sell.