Cannabis contaminants
By Rich Hamilton
Photos courtesy of Dinafem
There’s a stereotype that goes along with cannabis that is still alive today, a kind of hippy mentality, that leads people to assume that all growers are using natural cultivation methods when many of us know that this is not the case at all. The truth is if you are buying your weed on the black market you really have no idea how it is being grown and what it contains. Contamination is not always intentional however and even growers with the best intentions can still unknowingly introduce contaminants such as fungi and bacteria and heavy metals into their crops and it can happen during growing, harvesting, handling, extracting, or storing cannabis. Some contaminations like mould or mildew can be spotted easily on sight but identifying levels of heavy metals is more difficult and requires a chemical analysis. This means that the every day home grower is often oblivious to the existence and the levels of the contaminants that could be present.
It's not just a home growers problem however. Even cannabis sold in dispensaries where it is legal in the US and Canada can be at risk unless it is subject too very strict lab testing regulations. This is because it is common practice that cannabis will be subject to lab tests for cannabinoid and terpene content and not contaminants. So with this in mind ask yourself, do you know what's in your weed? Or how it got there? I suspect that the answer from the majority of people would be a resounding "no" which is exactly why I thought it would be interesting to look closer at the heavy metal contaminants that can be present in cannabis and how if possible to avoid contamination as far as you can in your own grows.
Did you know that cannabis is part of a category of plants labelled “accumulator plants”? This means that they are super efficient at sucking in and storing materials. This might sound kind of cool on the surface and useful if you are a grower however it can be just as much of a hindrance as it is a help because it just exacerbates the problem of potential contamination. Pretty much everything that comes into contact with your plants and assists in their development such as fertilisers, water, soil, air, and root zone media more often than not, contains varying levels of toxic heavy metals and other pollutants that your cannabis plants as “accumulators” will take in to their vascular system and store. Heavy metals are metallic chemical elements with high densities that can be toxic even at low levels, naturally found in the earths crust it is inevitable that we will be exposed to them naturally at a low level through the food we eat, air we breathe and the water we drink. Cannabis in its natural environment like all plants will contain a quantity of heavy metals that corresponds to the quantity that is present in the soil in which they are growing.
The list of heavy metals” includes arsenic a known carcinogen that in toxic doses can kill and is linked to many different cancers. Cadmium which is a zinc byproduct that is extremely toxic and carcinogenic and can cause respiratory illnesses and kidney disease. Lead which over exposure to can result in poisoning leading to headaches, intestinal stress, pain and reproductive problems. Mercury which can cause serious neurological damage, pain, numbness, tremors, difficulty walking, seizures and memory problems and Nickel, large doses of which can cause stomach problems, heart failure, kidney and lung damage, neurological problems, dermatitis and cancer. Other contaminants on the list include iron and copper.
You may think, well so what? I’ve been smoking for years and I’m fine, but are you really? Are you willing to ignore the multitude of possible health risks that could affect you in future years? Effects from heavy metals are not felt overnight, the toxins slowly accumulate in our bodies over time. In scientific tests it was found that anywhere between 6%-23% of heavy metals are transferred from plant matter to smoke when they are burned. So thinking of that every time you light up a joint may change your mind on the conscious thought that you put into your growing methods!
The majority of heavy metals enter cannabis primarily via hydroponics nutrients, fertilisers, and soils. There will be extremely low levels of some contaminants that are present in your water supply but on their own they are usually low enough that they are insignificant by themselves, this is in big part due to the treatment of our domestic water supply before it reaches our homes. If you were using a fresh or untreated water source you may find higher levels present. Growing in soil is also a contributing factor as soil will already naturally contain a whole heap of chemical elements dependent on where it has originated from and what it has been exposed to both organically and environmentally such as animal waste or industrial byproducts and fumes. The biggest culprit however is thought to be poor quality nutrients and fertilisers that are not made to the correct specifications and/or do not include the correct ingredients at safe levels levels. These feeds and fertilisers tend to contain cheap, low grade elements in order to keep costs down and should be avoided at all costs. If ever there was a perfect example of the phrase "you get what you pay for" it is this instance.
One of the main routes from that brings contamination into the plant through feeds and fertilisers is phosphorous, the P in your NPK, an essential macronutrient that is required in large amounts by your plants. Phosphorous is often a carrier material that contains radiation and heavy metals. In fact in raw form such as rock phosphate for example it can contain substantial amounts of toxic contamination. Not only this but phosphorous is also a natural chelator meaning that it binds with heavy metals and other toxic substances.Phosphorous plays an important and varied role in plant health, aiding in photosynthesis, respiration, energy storage and transfer, cell division, cell enlargement and several other minor processes. It is no surprise then that a feeding regime heavy in phosphorous is very common in hydroponics and indoor growing. You will find that almost all nutrients, medium and fertilisers available on the market today contain far more phosphorous than your plants really need, especially for the first few weeks of Flower.
Too much phosphorous can have the opposite effect than you would want/expect it to have on your plants, causing imbalance from the root up and disrupting growth, health, and yield whilst also storing toxic heavy metals and radiation in your crops which then enters your body when you ingest the cannabis. Zinc can also cause issues, an essential micronutrient contained in your plant feed, it is required in much smaller amounts and is an important part of many enzymes and proteins as well as being essential to processes such as growth hormone production. Although only a small amount is needed by your plant zinc can still be a risk to health as it may contain lead, cadmium, and Mercury all of which can be a danger if repeatedly ingested over time.
There are often “heavy metals analysis” statements on fertiliser labels showing you that levels are safe, this is due to organisations that have introduced and are reinforcing standards of acceptable levels of heavy metals in fertilisers that are safe for human consumption. This is a great start and whilst tests do show that the threat of toxic heavy metal ingestion from the use of chemical fertiliser is low, lets not forget that the hydroponics industry and the specific fertilisers used within it are largely still unregulated and not standardised and so any fertiliser regulatory standards that do exist don’t protect us, and neither do most fertiliser manufacturers. With this in mind you must take it seriously that the analysis on your nutrient bottle may not be telling you the full truth as to what is in there!
So what is the best way to avoid using products that may contain unsafe levels of heavy metals and other chemical contaminants? Well it would be to do your research on what you are using and to choose reputable brands who back up their claims, wherever possible. This might mean spending a bit more money but as I always say, you get what you pay for. Look out for products that use pharmaceutical-grade metal salts called proteinates, and alaninates, which are cleaner, high quality and more thoroughly tested and so therefore far more likely to eliminate contamination issues. Let's face it the clue here is in the name "pharmaceutical" which shows that they are clean enough to pass strict regulations for use in medical products, which also makes perfect sense if you are in fact growing your own cannabis for medicinal because after all you essentially want to use it to make your health better not worse.
Using the right amounts and types of these chemical elements has a twofold effect in that it not only protects your health but it also makes for stronger, larger, cleaner plants with higher levels of THC and other cannabinoids. Most nutrients that use pharmaceutical grade elements also tend to be more specific with the measurements that their products include such as using the correct ratio of phosphorous rather than the overdoses that you see in less meticulous brands.
In terms of organic nutrients, do not be fooled that the word "organic" means clean of heavy metals. Remember that heavy metals are present naturally in the environment and so will be present in any animal matter that is used in your organic fertiliser. Examples include fish which depending on its origin can be high in mercury and bat guano which contains higher levels of arsenic and several other metals. If you are insistent on wanting to use organic nutrients for other reasons such as reducing use of synthetic fertilisers then I would advise you again to do your research and buy the best quality organic products that you can afford as similarly to pharmaceutical grade nutrients the ingredients will be much more thoroughly screened and safer. Alternatively you could try using Vegan nutrients which are making a real impact at the moment and are very low in heavy metal content as the formulas are made up entirely of plant matter, with no synthetic chemicals or animal based derivatives. Tests have shown that weed grown using organic methods and techniques can still contain contaminants (heavy metals) at levels of around 2-5 parts per million, whereas weed grown on a vegan feeding schedule comes in at more like 200-600 parts per billion, which is over 100 times less!
Using a medium such as coco coir will help keep levels to a minimum due to the fact that it is inert, rather than soil which already comes pre-loaded with an unknown amount of elements that are hard to control. If you are growing in a hydro system (DWC,NFT, aeroponics) where your plants are much more exposed to any heavy metal traces present in your water supply, then I would recommend the use of RO (reverse osmosis) or demineralised water which has a much, much lower level of heavy metals present.
Flushing your plants at the end of Flower and before Harvest is an essential practice that everyone should follow, however I now realise that it is not enough by itself to protect myself or anyone else who would be smoking my end product. There will still be traces of questionable chemicals in your plants no matter how or what you use to flush them and so my advice would be to look a little deeper and try to eliminate the problem much earlier on and give yourself the peace of mind that you are doing all you can to look after your health!
Did you know that cannabis is part of a category of plants labelled “accumulator plants”? This means that they are super efficient at sucking in and storing materials. This might sound kind of cool on the surface and useful if you are a grower however it can be just as much of a hindrance as it is a help because it just exacerbates the problem of potential contamination. Pretty much everything that comes into contact with your plants and assists in their development such as fertilisers, water, soil, air, and root zone media more often than not, contains varying levels of toxic heavy metals and other pollutants that your cannabis plants as “accumulators” will take in to their vascular system and store. Heavy metals are metallic chemical elements with high densities that can be toxic even at low levels, naturally found in the earths crust it is inevitable that we will be exposed to them naturally at a low level through the food we eat, air we breathe and the water we drink. Cannabis in its natural environment like all plants will contain a quantity of heavy metals that corresponds to the quantity that is present in the soil in which they are growing.
The list of heavy metals” includes arsenic a known carcinogen that in toxic doses can kill and is linked to many different cancers. Cadmium which is a zinc byproduct that is extremely toxic and carcinogenic and can cause respiratory illnesses and kidney disease. Lead which over exposure to can result in poisoning leading to headaches, intestinal stress, pain and reproductive problems. Mercury which can cause serious neurological damage, pain, numbness, tremors, difficulty walking, seizures and memory problems and Nickel, large doses of which can cause stomach problems, heart failure, kidney and lung damage, neurological problems, dermatitis and cancer. Other contaminants on the list include iron and copper.
You may think, well so what? I’ve been smoking for years and I’m fine, but are you really? Are you willing to ignore the multitude of possible health risks that could affect you in future years? Effects from heavy metals are not felt overnight, the toxins slowly accumulate in our bodies over time. In scientific tests it was found that anywhere between 6%-23% of heavy metals are transferred from plant matter to smoke when they are burned. So thinking of that every time you light up a joint may change your mind on the conscious thought that you put into your growing methods!
The majority of heavy metals enter cannabis primarily via hydroponics nutrients, fertilisers, and soils. There will be extremely low levels of some contaminants that are present in your water supply but on their own they are usually low enough that they are insignificant by themselves, this is in big part due to the treatment of our domestic water supply before it reaches our homes. If you were using a fresh or untreated water source you may find higher levels present. Growing in soil is also a contributing factor as soil will already naturally contain a whole heap of chemical elements dependent on where it has originated from and what it has been exposed to both organically and environmentally such as animal waste or industrial byproducts and fumes. The biggest culprit however is thought to be poor quality nutrients and fertilisers that are not made to the correct specifications and/or do not include the correct ingredients at safe levels levels. These feeds and fertilisers tend to contain cheap, low grade elements in order to keep costs down and should be avoided at all costs. If ever there was a perfect example of the phrase "you get what you pay for" it is this instance.
One of the main routes from that brings contamination into the plant through feeds and fertilisers is phosphorous, the P in your NPK, an essential macronutrient that is required in large amounts by your plants. Phosphorous is often a carrier material that contains radiation and heavy metals. In fact in raw form such as rock phosphate for example it can contain substantial amounts of toxic contamination. Not only this but phosphorous is also a natural chelator meaning that it binds with heavy metals and other toxic substances.Phosphorous plays an important and varied role in plant health, aiding in photosynthesis, respiration, energy storage and transfer, cell division, cell enlargement and several other minor processes. It is no surprise then that a feeding regime heavy in phosphorous is very common in hydroponics and indoor growing. You will find that almost all nutrients, medium and fertilisers available on the market today contain far more phosphorous than your plants really need, especially for the first few weeks of Flower.
Too much phosphorous can have the opposite effect than you would want/expect it to have on your plants, causing imbalance from the root up and disrupting growth, health, and yield whilst also storing toxic heavy metals and radiation in your crops which then enters your body when you ingest the cannabis. Zinc can also cause issues, an essential micronutrient contained in your plant feed, it is required in much smaller amounts and is an important part of many enzymes and proteins as well as being essential to processes such as growth hormone production. Although only a small amount is needed by your plant zinc can still be a risk to health as it may contain lead, cadmium, and Mercury all of which can be a danger if repeatedly ingested over time.
There are often “heavy metals analysis” statements on fertiliser labels showing you that levels are safe, this is due to organisations that have introduced and are reinforcing standards of acceptable levels of heavy metals in fertilisers that are safe for human consumption. This is a great start and whilst tests do show that the threat of toxic heavy metal ingestion from the use of chemical fertiliser is low, lets not forget that the hydroponics industry and the specific fertilisers used within it are largely still unregulated and not standardised and so any fertiliser regulatory standards that do exist don’t protect us, and neither do most fertiliser manufacturers. With this in mind you must take it seriously that the analysis on your nutrient bottle may not be telling you the full truth as to what is in there!
So what is the best way to avoid using products that may contain unsafe levels of heavy metals and other chemical contaminants? Well it would be to do your research on what you are using and to choose reputable brands who back up their claims, wherever possible. This might mean spending a bit more money but as I always say, you get what you pay for. Look out for products that use pharmaceutical-grade metal salts called proteinates, and alaninates, which are cleaner, high quality and more thoroughly tested and so therefore far more likely to eliminate contamination issues. Let's face it the clue here is in the name "pharmaceutical" which shows that they are clean enough to pass strict regulations for use in medical products, which also makes perfect sense if you are in fact growing your own cannabis for medicinal because after all you essentially want to use it to make your health better not worse.
Using the right amounts and types of these chemical elements has a twofold effect in that it not only protects your health but it also makes for stronger, larger, cleaner plants with higher levels of THC and other cannabinoids. Most nutrients that use pharmaceutical grade elements also tend to be more specific with the measurements that their products include such as using the correct ratio of phosphorous rather than the overdoses that you see in less meticulous brands.
In terms of organic nutrients, do not be fooled that the word "organic" means clean of heavy metals. Remember that heavy metals are present naturally in the environment and so will be present in any animal matter that is used in your organic fertiliser. Examples include fish which depending on its origin can be high in mercury and bat guano which contains higher levels of arsenic and several other metals. If you are insistent on wanting to use organic nutrients for other reasons such as reducing use of synthetic fertilisers then I would advise you again to do your research and buy the best quality organic products that you can afford as similarly to pharmaceutical grade nutrients the ingredients will be much more thoroughly screened and safer. Alternatively you could try using Vegan nutrients which are making a real impact at the moment and are very low in heavy metal content as the formulas are made up entirely of plant matter, with no synthetic chemicals or animal based derivatives. Tests have shown that weed grown using organic methods and techniques can still contain contaminants (heavy metals) at levels of around 2-5 parts per million, whereas weed grown on a vegan feeding schedule comes in at more like 200-600 parts per billion, which is over 100 times less!
Using a medium such as coco coir will help keep levels to a minimum due to the fact that it is inert, rather than soil which already comes pre-loaded with an unknown amount of elements that are hard to control. If you are growing in a hydro system (DWC,NFT, aeroponics) where your plants are much more exposed to any heavy metal traces present in your water supply, then I would recommend the use of RO (reverse osmosis) or demineralised water which has a much, much lower level of heavy metals present.
Flushing your plants at the end of Flower and before Harvest is an essential practice that everyone should follow, however I now realise that it is not enough by itself to protect myself or anyone else who would be smoking my end product. There will still be traces of questionable chemicals in your plants no matter how or what you use to flush them and so my advice would be to look a little deeper and try to eliminate the problem much earlier on and give yourself the peace of mind that you are doing all you can to look after your health!
