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Cannabis Contamination: What is It and How To Identify It?

marijuana doctor in Los Angeles

What is the most important aspect to look out for while buying cannabis? Its quality. In fact, every marijuana doctor in Los Angeles advises to never compromise on the quality of cannabis. And the primary reason for such emphasis is health. 

Irrespective of whether you use medical or recreational cannabis, poor quality products can cause significant damage to your body. And this damage increases with longer use. Also, such products may not even be as potent as they should be. So you can brag about how expensive your stash is or what strain you have. It is not worth it if it’s not good quality.

But getting quality cannabis can be difficult nowadays. There are several types of contaminants that can be found in cannabis. These are either added voluntarily or are a result of improper care. In either case, you must refrain from using such cannabis products.  

How does cannabis contamination happen?

One of the biggest dangers for a cannabis consumer is cannabis contamination. There are several reasons why this happens. The first is the most obvious one- the black market. Most people rely on illegal sources to get a restock. However, there is really no proof of the quality of the product they sell. It may not only be of poor quality but also contain substances that you would not want in your body. For their personal gain, such sellers resort to adding contaminants to cannabis. This is usually done as a means to mask the poor quality of cannabis. 

Contaminants can also occur in some dispensary products. But these are not a voluntary addition. These contaminants may occur due to improper handling and care during or after the harvest process. The same is the case with homegrown marijuana. If you do not maintain proper growing conditions for the plant, your harvest may get contaminated. 

What possible contaminants are found in cannabis?

As already mentioned, cannabis contamination can be due to a lot of voluntary or involuntary reasons. This is why the list of contaminants is also not a small one.

Nevertheless, here are some of the most common types of contaminants found in cannabis. 

  • Mold
  • Solvent Residues
  • Metal 
  • Industrial Chemicals
  • Black Market Contaminants


It is very common for mold or fungus to grow on cannabis. It is usually found in the form of powdery mildew or gray mold. Molds can grow before, during and after the harvest. A slight change in temperature and humidity can start the development of these fungal growths on the plant. Ingestion of these contaminants can cause respiratory problems in the consumer. So the identification and elimination of moldy harvest is very important.

Solvent Residues

Most people prefer cannabis extracts for consumption. However, if the extraction process isn’t done with proper care and innocuous chemicals, the final product may contain contaminants. 

The extraction process of cannabis usually involves solvents like carbon dioxide, ethanol, butane and propane. But it is possible for the end product to have residuals of these chemicals. Butane and propane residues are more toxic than others and are more commonly found in illicit products. 


Cannabis can hoard up a large fraction of metal from the soil and store it in the flower. This metal is usually found in chemicals that are fed to the plants for faster growth. The metal in the buds can also show up in the end products such as cannabis extracts. 

Cannabis accessories that use metal such as vape pens can also expose the user to metal. It is usually caused by high temperatures involved in the process that releases the metal into the body. 

Industrial Chemicals

Pesticides, fungicides, fertilizers etc. are very commonly fed to the cannabis plant. These are used to ensure a high yield and prevent diseases and pest damage. However, most of these chemicals are absorbed by the plant and become a part of it. Consuming the same harvest can expose you to the damages caused by these chemicals. 

Black Market Contaminants

The black market has quite a reputation for tampering with their cannabis products. The most common of these contaminants are silica, sand, talcum powder and sugar. Each of these substances are added to increase the weight of the stash. And also to make the buds appear more trichome rich. 

How to look for signs of contamination?

There are rules and regulations in most states that keep a check on such contaminants. However, there are still some flaws in the implementation. Also, not all states follow the safety protocol of testing cannabis for contaminants. In the case of homegrown cannabis, it may depend on how well you are able to identify the contaminants on your own. So ultimately it all comes down to your experience and knowledge about cannabis. But don’t worry, here are some ways that can help you out. 

Have a closer look

You can easily identify mold on cannabis just by looking at it. Moldy cannabis appears to have specks of white substance or fuzziness on the surface. Some even have spider web layers and dark spots on the crevices of the buds. 

Pay attention to the color of the buds too. Good quality cannabis will have green shades with hues of purple or orange. Contaminated weed will be more towards shades of brown and gray.  

Feel the Texture and Taste

Take a moment to hold the buds and access its texture. Good quality bud should be at a sweet spot between dry and sticky. If your buds feel too spongy or sticky, it is possible that it has been sprayed with contaminants after harvest. On the other hand, if it is too dry or brittle, it means that it hasn’t been cured properly and may have added substances that give the appearance of trichomes. In case you feel that you may have grit weed, try rubbing it against the glass or chew on it. If you feel a crackling or scratchy sound, it is probably coated with silica.

Try tasting the bud if you feel suspicious about it. If it is tampered with, it will taste like chemicals.  

Look for peculiar smell

You must be aware of what good cannabis smells like. It usually has a fresh, herby or skunky smell. Or one according to its terpene profile. But in case you have a moldy stash or one that hasn’t been cured properly, it will smell like wet grass or human odor. Similarly, contaminants like talcum powder can easily be identified by smell. 

Observe your body’s response

If you have a product with no easily detectable contaminants, you may have to give it a try to make any conclusions. Once you consume it, keep a note of how your body responds. Do you have an allergic reaction, headache, nausea or other responses that you’ve never had before? If yes, then there’s a good chance that your stash is contaminated. And in case these symptoms persist, do not hesitate to contact a marijuana doctor in Los Angeles

Also, keep a check on the flavor and experience of consumption. Contaminated cannabis may have an aftertaste of chemicals. The ash of the joint also appears to be harder than it should be due to the combustion of added substances. If you experience either of the changes, dump your stash immediately. 

Now that you know all about cannabis contamination and how to identify it, stay safe and implement your knowledge next time you go for a purchase.

In light of the COVID pandemic, we advise all our patients to see a doctor online instead of visiting the clinic. Help us flatten the curve by opting for an online 420 evaluation.