Heavy Metals

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, the plants we consume and the water that we drink.  Examples of heavy metals include mercury, cadmium, arsenic, chromium, selenium, cobalt, lead, molybdenum, copper, iron, nickel and zinc. 

Are heavy metals bad for your health?  Some heavy metals are known carcinogens, such as arsenic, mercury, lead, and nickel.  On the other hand, heavy metals such as molybdenum, manganese, zinc, copper, and iron can be beneficial for the health of both plants and humans if consumed in low doses.  All parts of the plant including roots, stems and leaves have been scientifically proven to contain the quantity of heavy metals corresponding to their contents in the soil.  Our favorite plant is known as an accumulator plant, meaning that it will uptake most metals found both in the fertilizers and the media surrounding its root zone, which inevitably leads to uptake by humans through inhaling or consumption! 

What happens when you smoke heavy metals? 

6% - 23% of heavy metals have been scientifically found to transfer from plant matter to smoke when combusted. 

These are some of the more common heavy metals that pose a risk for human consumption of our favorite plant: 

  • 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 by product 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 nasty 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 by product 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. 

Clearly, we do NOT want the above heavy metals in our body but it’s not easy to know if the flower you buy at the dispensary is free from unwanted heavy metals.  There is a serious lack of state and federal regulations when it comes to lab testing, and this part of the industry is still in its early 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 molds and not for heavy metals. 

How do I avoid heavy metals in my flower? 

There are some simple remedies to growing clean pot.  Try to avoid using tap, well or rain water.  Reverse osmosis or demineralized water is free from heavy metals, although RO water is by far the cheapest option.  Know your media - clearly the use of soil or soilless media is going to bring more heavy metals into your weed than most inert, unamended media.  Growing using a water culture style (deep water culture, aeroponics, NFT) combined with RO water is definitely your best bet.  Then there are your fertilizers to consider.  Some ‘so called’ organic fertilizers seem to be the worst culprits for heavy metal content.  For example, fish, depending on its origin, can have high mercury content, while bat guano is notorious for excess arsenic and several other natsy metals., and low quality mineral fertilizers that typically use cheap grade elements to cut costs should also be avoided as they can bring unwelcome metals too!  Given the multitude of ways heavy metals can be found in fertilizers, both organic and inorganic, state agricultural departments have set maximum allowable limits to protect the environment and of course, us! 

American made Dutch Master Nutrients is one of the rare fertilizer manufacturers that proudly lists its heavy metal analytical reports for all products on their website showing zero detectable unwanted heavy metals!  A true testament to the high quality ingredients employed. 

So, are your flowers grown with heavy metal free fertilizers?...