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Are You Testing Your Plants for Heavy Metals?

February 28, 2019

Are You Testing Your Plants for Heavy MetalsYou don’t need an advanced degree in biology, chemistry, or biochemistry to know that certain metals are extremely hazardous to human health. Generally speaking, everyone knows the hazards associated with Arsenic. It’s a highly toxic heavy metal that has extreme detrimental effects on living tissue. Arsenic consumption drastically increases cancer risks, damages organs, lowers IQ, and in exceedingly high concentrations is frightfully lethal. What is not known by most is that Arsenic has many sibling elements that are just as destructive to the human body: Antimony, Thallium, Mercury, Cadmium, Chromium, Uranium – the list goes on. These elements are well known to those in the drinking water treatment business because of their low, part per billion range, safety limits set by the United States Environmental Protection Agency’s National Primary Drinking Water Regulations (pursuant to the Safe Drinking Water Act). To growers, these fickle atoms are not always well known.

By law, Arsenic levels in public drinking water must be below 10 parts per billion, Antimony below 6 parts per billion, and Thallium below an exceedingly smaller 2 parts per billion. The risk here is that, in both soil and hydroponic growth, most leafy green plants take up these metals and store them within their cells. As plants take up contaminated water sources, they continue to store what is available, biologically speaking the plants don’t know what to do with these metals. They can’t use them within their metabolic processes, so they are just tucked away. A hydroponic plant exposed to an EPA acceptable level of arsenic contamination, say just 1 part per billion (1/10th the allowable limit), will slowly concentrate and accumulate arsenic. Given ample time a sampling from the leafy green plant would reveal arsenic levels in the hundreds or even thousands of parts per billion.

Though the human metabolic process will react differently to absorption through the skin or inhalation as opposed to drinking water consumption, there is still a biological uptake of these heavy metals. The very product that is consumed, in some cases, to ease or treat the symptoms of cancer may be imparting heavy metals that elevate carcinogenic risks. In terms of quality, reputable growers are certain and confident of their products’ purity and that it is free of solvent and pesticide contaminates. But are they certain it is free of these heavy metals?

Perhaps an exercise in scale is required, after all what is a part per billion? In strict scientific terms it is a compound that exists in a ratio of one microliter per liter of aqueous (liquid) or one microgram per kilogram of solid material. In laymen’s terms this can be expressed by rounding up the entire human population of North America, putting them in an admittedly large room and asking everyone to wear a blue shirt. Now, if you wish to demonstrate what 10 parts per billion is, you would ask just five people to wear red shirts instead of blue. The astronomical futility in this exercise is apparent, the numbers we are discussing are an order of magnitude so finite it is all but inconceivable to the human mind. We struggle to grasp and comprehend the absolute miniscule nature of these numbers. Yet, these numbers set standards and limits for safe, clean drinking water and by extension should also be accounted for when assessing the safety and usability of hydroponic water sources.

But here in Maine most of us have well water. We all believe that well water is the best water. Well, unfortunately, we are wrong. According to a 2005-2009 study conducted by the United States Geological Survey, domestic well water in Maine by town has some shockingly high rates of arsenic contamination. It is, in fact, a common groundwater contaminant and therefore if left untreated when used as a hydroponic source it will impart arsenic concentrations to the leafy green plants grown. Arsenic, like most health hazardous heavy metals, is tasteless, colorless, and odorless when dissolved in water at these concentrations. Just because the water tastes fine, smells fine, and looks fine does not mean a dangerous and detrimental contaminate does not lie within.

The most proactive testing that can be done starts with the water used to grow. Test the water for these heavy metals, if they are not present then you need not worry. But if they are present even in levels below US EPA advisory levels, they can and will concentrate in leafy green plants and risk the health of those that consume them. Even if the water is treated, reverse osmosis for example, it should be tested before and after the treatment system to ensure it is working properly and it is removing 100% of all detectable levels of these contaminates. Some of these metals, Arsenic in particular, can only be removed by specialized targeted treatment system. Your normal home use filtration system from the big boxed stores may not help, and any use of boiling the water to make it sterile will further concentrate these minerals and only increase their potency. Begin safeguarding against heavy metal contamination today, test the water and soil you use to grow your crops. It’s proactive, it’s informative, and puts you well ahead of the ball for when regulations are finally in place.

The mission of Northeast Laboratory Services (NEL) has always been to promote a healthy and safe environment by advancing science, principles, and education. NEL is not only committed to protecting and improving healthy environments in our public and private buildings, but the health and well-being of all the people in our great State of Maine, now and in the future. Our Indoor Air Quality (IAQ) laboratory is AIHA-LAP, LLC (ID #: 102960) accredited. Northeast Laboratory Services prides itself on providing quality analytical results and personable service at competitive pricing. For more information, contact Northeast Laboratory Services at:
1-800-244-8378 or visit our website:

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