heavy metals in cannabis
heavy metals in cannabis

The Dangers of Heavy Metals in Your Cannabis

Organic Cannabis is the Best Way to Go

Posted by:
DanaSmith on Friday Oct 6, 2017

The Dangers of Heavy Metals in Your Cannabis

Are There Heavy Metals in Your Cannabis Plants or Products? from CannabisNet on Vimeo.


There has been an increased focus on the quality of cannabis, and with good reason. Testing laboratories show that an alarming amount of cannabis contains things that you don’t want to put in your body, like toxic pesticides, and now, heavy metals.


It only makes sense since you wouldn’t put these harmful chemicals in your body when you eat food, and cannabis wouldn’t be true medicine if it’s laced with pesticides and heavy metals. But while more of the community is focused on pesticide testing, let’s talk about heavy metals, and what their dangers are.


Science confirms that cannabis plants absorb heavy metals from the soil that they grow in, and the more THC the plant contains, the more heavy metals it will absorb. Most growers don’t recognize the importance of this information, and the impact it has on consumer health. Since cannabis is an accumulator plant, it takes in everything found in its environment, including the soil.


What are heavy metals?


Heavy metals are metallic chemical elements that have high densities and are toxic even at low concentrations. These are naturally found in the earth’s crust, so it’s inevitable that we are exposed to them through the air we breathe, the food we eat, and the water that we drink. Now it’s in our medicine too. Some heavy metals are known carcinogens, such as arsenic, mercury, lead, and nickel. On the other hand, other heavy metals such as zinc, copper, and iron can be beneficial for the health of both plants and humans if taken in low doses.


human body

Toxic Effects On The Human Body


These are the common heavy metals that pose a problem for agriculture, including cannabis cultivation:


  • Arsenic is a well-known poison to humans; in fact it’s even been used to commit murder. Ingesting or consuming high doses of arsenic can cause violent vomiting, clammy hands, diarrhea, reduced blood pressure, and even death due to the lack of blood flow. Arsenic is also a carcinogen that has been linked to many kinds of cancers.


  • Cadmium is the byproduct of zinc, and it is used in manufacturing. Cadmium is a carcinogenic and is extremely poisonous; it targets the cardiovascular, neurological, respiratory, reproductive, gastrointestinal, and renal systems. Burning fossil fuels releases cadmium to the air, and breathing it in can irritate the lungs. Large amounts of cadmium are linked to kidney damage, cancer, and bone fractures.


  • Nickel is a heavy metal that the human body has evolved to absorb in small quantities safely over time. Much of the nickel we are exposed to, such as through particles in the air or other nickel products, are removed by the kidneys and excreted in the urine. But large doses of nickel can cause stomach aches, heart failure, kidney and lung damage, neurological effects, gastrointestinal distress, dermatitis, and cancer.



  • Lead is another notorious poison that is known to cause fatal health problems particularly in children who may suffer from learning disabilities and developmental delays. For adults, symptoms of lead poisoning include intestinal distress, headaches, joint pain, and reproductive problems. Although lead used to be used for the manufacture of pencils or paint, it’s still commonly found in the soil and in the air.


  • Mercury is a byproduct of burning coal, and can cause severe neurological damage. Signs of mercury poisoning include tremors, coronary heart disease, psychological changes, numbness, pain, memory problems, difficulty walking, and seizures.


Naturally, we don’t want these heavy metals in our body but it’s difficult to know if the cannabis you buy at the dispensary is free from heavy metals. There is a serious lack of regulations when it comes to testing, and this part of the cannabis industry is still in its infancy stage. There has been a growth of independent laboratories dedicated to testing to fill this void and ensure patient safety; however, many of these laboratories only test for pesticides and not for heavy metals.


When shopping for cannabis at a dispensary, the only way you can make sure that you’re not ingesting any heavy metals with your bud is by asking the budtender to show you strains or products that have been tested specifically for heavy metals. If they don’t have any, you might want to consider another dispensary. Keep in mind that concentrates also tend to have higher THC concentrations which means that they are also more likely to have more heavy metals. 











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