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Analytical Instruments You Need to Start a Cannabis Testing Laboratory

By Bob Clifford
2 Comments

The cannabis industry is growing exponentially, and the use of cannabis for medical purposes is being adopted across the nation. With this boom in cannabis consumers, there has been an increasing need for knowledge about the product.

The role of testing labs has become crucial to the process, which makes owning and operating a lab more lucrative. Scientists testing for potency, heavy metals, pesticides, residual solvents, moisture, terpene profile, microbial and fungal growth, and mycotoxins/aflatoxins are able to make meaningful contributions to the medical industry by making sure products are safe, while simultaneously generating profits and a return on investment.

Here are the key testing instruments you need to conduct these critical analyses. Note that cannabis analytical testing requirements may vary by state, so be sure to check the regulations applicable to the location of your laboratory.

Potency Testing

High-performance liquid chromatograph (HPLC) designed for quantitative determination of cannabinoid content.

The most important component of cannabis testing is the analysis of cannabinoid profiles, also known as potency. Cannabis plants naturally produce cannabinoids that determine the overall effect and strength of the cultivar, which is also referred to as the strain. There are many different cannabinoids that all have distinct medicinal effects. However, most states only require testing and reporting for the dry weight percentages of delta-9-tetrahydrocannabinol (Δ9-THC) and cannabidiol (CBD). It should be noted that delta-9-tetrahydrocannabinolic acid (Δ9-THCA) can be converted to THC through oxidation with heat or light.

For potency testing, traditional high-performance liquid chromatography (HPLC) is recommended and has become the gold standard for analyzing cannabinoid profiles. Look for a turnkey HPLC analyzer that delivers a comprehensive package that integrates instrument hardware, software, consumables and proven HPLC methods.

Heavy Metal Testing

ICP-MS instrument for detecting heavy metals in cannabis.

Different types of metals can be found in soils and fertilizers, and as cannabis plants grow, they tend to draw in these metals from the soil. Heavy metals are a group of metals considered to be toxic, and the most common include lead, cadmium, arsenic and mercury. Most labs are required to test and confirm that samples are under the allowable toxic concentration limits for these four hazardous metals.

Heavy metal testing is performed by inductively coupled plasma mass spectrometry (ICP-MS). ICP-MS uses the different masses of each element to determine which elements are present within a sample and at what concentrations. Make sure to include accompanying software that provides assistant functions to simplify analysis by developing analytical methods and automatically diagnosing spectral interference. This will provide easy operation and analytical results with exceptionally high reliability.

To reduce running costs, look for a supporting hardware system that reduces the consumption of argon gas and electricity. For example, use a plasma ignition sequence that is optimized for lower-purity argon gas (i.e., 99.9% argon as opposed to more expensive 99.9999%).

Pesticide Testing

The detection of pesticides in cannabis can be a challenge. There are many pesticides that are used in commercial cannabis grow operations to kill the pests that thrive on the plants and in greenhouses. These chemicals are toxic to humans, so confirming their absence from cannabis products is crucial. The number of pesticides that must be tested for varies from state to state, with Colorado requiring only 13 pesticides, whereas Oregon and California require 59 and 66 respectively. Canada has taken it a step further and must test for 96 pesticides, while AOAC International is developing methods for testing for 104 pesticides. The list of pesticides will continue to evolve as the industry evolves.

Testing for pesticides is one of the more problematic analyses, possibly resulting in the need for two different instruments depending on the state’s requirements. For a majority of pesticides, liquid chromatography mass spectrometry (LCMS) is acceptable and operates much like HPLC but utilizes a different detector and sample preparation.

With excellent sensitivity and ultra-low detection limits, LC-MS/MS is an ideal technique for the analysis of pesticides.

Pesticides that do not ionize well in an LCMS source require the use of a gas chromatography mass spectrometry (GCMS) instrument. The principles of HPLC still apply – you inject a sample, separate it on a column and detect with a detector. However, in this case, a gas (typically helium) is used to carry the sample.

Look for a LC-MS/MS system or HPLC system with a triple quadrupole mass spectrometer that provides ultra-low detection limits, high sensitivity and efficient throughput. Advanced systems can analyze more than 200 pesticides in 12 minutes.

For GCMS analysis, consider an instrument that utilizes a triple quadrupole mass spectrometer to help maximize the capabilities of your laboratory. Select an instrument that is designed with enhanced functionality, analysis software, databases and a sample introduction system. Also include a headspace autosampler, which can also be used for terpene profiles and residual solvent testing.

Residual Solvent Testing

Residual solvents are chemicals left over from the process of extracting cannabinoids and terpenes from the cannabis plant. Common solvents for such extractions include ethanol, butane, propane and hexane. These solvents are evaporated to prepare high-concentration oils and waxes. However, it is sometimes necessary to use large quantities of solvent in order to increase extraction efficiency and to achieve higher levels of purity. Since these solvents are not safe for human consumption, most states require labs to verify that all traces of the substances have been removed.

Testing for residual solvents requires gas chromatography (GC). For this process, a small amount of extract is put into a vial and heated to mimic the natural evaporation process. The amount of solvent that is evaporated from the sample and into the air is referred to as the “headspace.” The headspace is then extracted with a syringe and placed in the injection port of the GC. This technique is called full-evaporated technique (FET) and utilizes the headspace autosampler for the GC.

Look for a GCMS instrument with a headspace autosampler, which can also be used for pesticide and terpene analysis.

Terpene Profile Testing

Terpenes are produced in the trichomes of the cannabis leaves, where THC is created, and are common constituents of the plant’s distinctive flavor and aroma. Terpenes also act as essential medicinal hydrocarbon building blocks, influencing the overall homeopathic and therapeutic effect of the product. The characterization of terpenes and their synergistic effect with cannabinoids are key for identifying the correct cannabis treatment plan for patients with pain, anxiety, epilepsy, depression, cancer and other illnesses. This test is not required by most states, but it is recommended.

The instrumentation that is used for analyzing terpene profiles is a GCMS with headspace autosampler with an appropriate spectral library. Since residual solvent testing is an analysis required by most states, all of the instrumentation required for terpene profiling will already be in your lab.

As with residual solvent testing, look for a GCMS instrument with a headspace autosampler (see above). 

Microbe, Fungus and Mycotoxin Testing

Most states mandate that cannabis testing labs analyze samples for any fungal or microbial growth resulting from production or handling, as well as for mycotoxins, which are toxins produced by fungi. With the potential to become lethal, continuous exposure to mycotoxins can lead to a buildup of progressively worse allergic reactions.

LCMS should be used to qualify and identify strains of mycotoxins. However, determining the amount of microorganisms present is another challenge. That testing can be done using enzyme linked immunosorbent assay (ELISA), quantitative polymerase chain reaction (qPCR) or matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), with each having their advantages and disadvantages.

For mycotoxin analysis, select a high-sensitivity LC-MS/MS instrument. In addition to standard LC, using an MS/MS selective detector enables labs to obtain limits of detection up to 1000 times greater than conventional LC-UV instruments.

For qPCR and its associated needs, look for a real-time PCR amplification system that combines thermal cyclers with optical reaction modules for singleplex and multiplex detection of fluorophores. These real-time PCR detection systems range from economical two-target detection to sophisticated five-target or more detection systems. The real-time detection platform should offer reliable gradient-enabled thermal cyclers for rapid assay optimization. Accompanying software built to work with the system simplifies plate setup, data collection, data analysis and data visualization of real-time PCR results.

Moisture Content and Water Activity Testing

Moisture content testing is required in some states. Moisture can be extremely detrimental to the quality of stored cannabis products. Dried cannabis typically has a moisture content of 5% to 12%. A moisture content above 12% in dried cannabis is prone to fungal growth (mold). As medical users may be immune deficient and vulnerable to the effects of mold, constant monitoring of moisture is needed. Below a 5% moisture content, the cannabis will turn to a dust-like texture.

The best way to analyze the moisture content of any product is using the thermogravimetric method with a moisture balance instrument. This process involves placing the sample of cannabis into the sample chamber and taking an initial reading. Then the moisture balance instrument heats up until all the moisture has been evaporated out of the sample. A final reading is then taken to determine the percent weight of moisture that was contained in the original sample.

A moisture balance can provide accurate determination of moisture content in cannabis.

Look for a moisture balance that offers intuitive operation and quick, accurate determination of moisture content. The pan should be spacious enough to allow large samples to be spread thinly. The halogen heater and reflector plate should combine to enable precise, uniform heating. Advanced features can include preset, modifiable measurement modes like automated ending, timed ending, rapid drying, slow drying and step drying.

Another method for preventing mold is monitoring water activity (aW). Very simply, moisture content is the total amount of water available, while water activity is the “free water” that could produce mold. Water activityranges from 0 to 1. Pure water would have an aW of 1.0. ASTM methods D8196-18 and D8297-18 are methods for monitoring water activity in dry cannabis flower. The aW range recommended for storage is 0.55 to 0.65. Some states recommend moisture content to be monitored, other states monitor water activity, and some states such as California recommend monitoring both.

Final Thoughts

As you can see, cannabis growers benefit tremendously from cannabis testing. Whether meeting state requirements or certifying a product, laboratory testing reduces growers’ risk and ensures delivery of a quality product. As medicinal and recreational cannabis markets continue to grow, analytical testing will ensure that consumers are receiving accurately

labeled products that are free from contamination. That’s why it is important to invest in the future of your cannabis testing lab by selecting the right analytical equipment at the start of your venture.

Sustainable Plastic Packaging Options for Your Cannabis Products

By Danielle Antos
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A large part of your company’s brand image depends on the packaging that you use for your cannabis product. The product packaging creates a critical first impression in a potential customer’s mind because it is the first thing they see. While the primary function of any cannabis packaging is to contain, protect and identify your products, it is a reflection of your company in the eyes of the consumer.

For all types of businesses across the US, sustainability has become an important component for success. It is increasingly common for companies to include sustainability efforts in their strategic plan. Are you including a sustainability component in your cannabis business’ growth plan? Are your packaging suppliers also taking sustainability seriously? More and more, consumers are eager to purchase cannabis products that are packaged thoughtfully, with the environment in mind. If you are using or thinking about using plastic bottles and closures for your cannabis products, you now have options that are produced from sustainable and/or renewable resources. Incorporating sustainable elements into your cannabis packaging may not only be good for the environment, but it may also be good for your brand.

Consider Alternative Resins

Traditionally, polyethylene produced from fossil fuels (such as oil or natural gas), has been used to manufacture HDPE (high density polyethylene) bottles and closures. However, polyethylene produced from ethanol made from sustainable sources like sugarcane (commonly known as Bioresin) are becoming more common.

HDPE bottles produced with Bioresin.

Unlike fossil fuel resources which are finite, sustainable resources like sugarcane are renewable – plants can be grown every year. For instance, a benefit of sugarcane is that it captures and fixes carbon dioxide from the atmosphere every growth cycle. As a result, production of ethanol-based polyethylene contributes to the reduction of greenhouse gas emissions when compared to conventional polyethylene made from fossil fuels, while still exhibiting the same chemical and physical properties as conventional polyethylene. Although polyethylene made from sugarcane is not biodegradable, it can be recycled.

Switching to a plastic bottle that is made from ethanol derived from renewable resources is a great way for cannabis companies to take positive climate change action and help reduce their carbon footprint.

For instance, for every one ton of Bioresin used, approximately 3.1 tons of carbon dioxide is captured from the atmosphere on a cradle-to-gate basis. Changing from a petrochemical-derived polyethylene bottle to a bottle using resins made from renewable resources can be as seamless as approving an alternate material – the bottles look the same. Ensure that your plastic bottle manufacturer is using raw materials that pass FDA and ASTM tests. This is one way to help reverse the trend of global warming due to increasing levels of carbon dioxide (CO2) in our atmosphere.

PET bottles derived from 100% recycled post-consumer material.

Another option is to use bottles manufactured with recycled PET (polyethylene terephthalate). Consisting of resin derived from 100% recycled post-consumer material, it can be used over and over. This is an excellent choice because it helps keep plastic waste to a minimum. Regardless of the resin you select, look for one that is FDA approved for food contact.

Consider Alternative Manufacturing Processes

Flame Treatment Elimination

When talking about plastic bottle manufacturing, an easy solution to saving fossil fuels is eliminating the flame treatment in the manufacturing process. Historically, this process was required to allow some water-based adhesives, inks, and other coatings to bond with HDPE (high density polyethylene) and PP (polypropylene) bottles. Today, pressure-sensitive and shrink labels make this process unnecessary. Opt out and conserve natural gas. For instance, for every 5 million bottles not flamed approximately 3 metric tons of CO2is eliminated. This is an easy way to reduce the carbon footprint. Ask your cannabis packaging manufacturer if eliminating this process is an option.

Source Reduction (Right-Weighting)

When considering what type and style of bottle you want to use for your cannabis product, keep in mind that the same bottle may be able to be manufactured with less plastic. A bottle with excess plastic may be unnecessary and can result in wasted plastic or added costs. On the other hand, a bottle with too little plastic may be too thin to hold up to filling lines or may deform after product is filled. Why use a bottle that has more plastic than you actually need for your product when a lesser option may be available? This could save you money, avoid problems on your filling lines, and help you save on your bottom line. In addition, this will also help limit the amount of natural resources being used in production.

Convert to Plastic Pallets

If you are purchasing bottles in large quantities and your supplier ships on pallets, consider asking about plastic pallets. Reusable plastic pallets last longer than wood pallets, eliminate pallet moisture and improve safety in handling. They also reduce the use of raw materials in the pallet manufacturing process (natural gas, metal, forests, etc.) aiding in efforts towards Zero Net Deforestation. And, returnable plastic pallets provide savings over the long term.

If You Don’t Know, Ask Your Cannabis Packaging Partner

It is important to find out if your plastic packaging partner offers alternative resins that are produced from renewable sources or recycled plastics. It is also prudent to partner with a company that is concerned about the impact their business has on the planet. Are they committed to sustainability? And, are they eliminating processes that negatively affect their carbon footprint? What services can they provide that help you do your part?

When you opt to use sustainably produced plastic bottles and closures for your cannabis products, you take an important step to help ensure a viable future for the planet. In a competitive market, this can improve the customer’s impression of your brand, increase consumer confidence and help grow your bottom line. Not only will you appeal to the ever-growing number of consumers who are environmentally-conscience, you will rest easy knowing that your company is taking action to ensure a sustainable future.

Cannabusiness Sustainability

Environmental Sustainability in Cultivation: Part 3

By Carl Silverberg
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Part 1 in this series went into a discussion of resource management for cannabis growers. Part 2 presented the idea of land use and conservation. In Part 3 below, we dive into pesticide use and integrated pest management for growers, through an environmental lens.

Rachel Carson’s book Silent Spring in 1962, is often credited with helping launch the environmental movement. Ten years later, VP Edmund Muskie elevated the environment to a major issue in his 1972 Presidential campaign against Richard Nixon. 57 years after Ms. Carson’s book, we’re still having the same problems. Over 13,000 lawsuits have been filed against Monsanto and last month a jury in Alameda County ruled that a couple came down with non-Hodgkin’s lymphoma because of their use of Roundup. The jury awarded them one billion dollars each in punitive damages. Is there a safer alternative?

“Effectively replacing the need for pesticides, we use Integrated Pest Management (IPM) which is a proactive program designed to control the population of undesirable pests with the use of natural predators, a system commonly known as “good bugs (such as ladybugs) fighting bad bugs”, states the website of Mucci Farms, a greenhouse grower. While this applies to cannabis as well, there is one major problem with the crop that isn’t faced by other crops.

Rachel Carson’s Silent Spring- often credited with starting the environmental movement of the 20th century.

While states are moving rapidly to legalize it, the EPA is currently not regulating cannabis. That is in the hands of each state. According to a story in the Denver Post in 2016, “Although pesticides are widely used on crops, their use on cannabis remains problematic and controversial as no safety standards exist.” Keep in mind that it takes a lot more pesticides to keep unwarranted guests off your cannabis plant when it’s outdoors than when it’s in a controlled environment.

We’re accustomed to using endless products under the assumption that a range of governmental acronyms such as NIH, FDA, OSHA, EPA, USDA are protecting us. We don’t even think about looking for their labels because we naturally assume that a product we’re about to ingest has been thoroughly tested, approved and vetted by one of those agencies. But what if it’s not?

Again, cannabis regulation is at the state level and here’s why that’s critical. The budget of the EPA is $6.14 billion while Colorado’s EPA-equivalent agency has a budget of $616 million. According to the federal budget summary, “A major component of our FY 2019 budget request is funding for drinking water and clean water infrastructure as well as for Brownfields and Superfund projects.” In short, federal dollars aren’t going towards pesticide testing and they’re certainly got going towards a product that’s illegal at the federal level. That should make you wonder how effective oversight is at the state level.

What impact does this have on our health and what impact do pesticides have on the environment? A former Dean of Science and Medical School at a major university told me, “Many pesticides are neurotoxins that affect your nervous system and liver. These are drugs. The good news is that they kill insects faster than they kill people.” Quite a sobering thought.

“We have the ability to control what kinds of pesticides we put in our water and how much pesticides we put in our water.”Assuming that he’d be totally supportive of greenhouses, I pushed to see if he agreed. “There’s always a downside with nature. An enclosure helps you monitor access. If you’re growing only one variety, your greenhouse is actually more susceptible to pests because it’s only one variety.” The problem for most growers is that absent some kind of a computer vision system in your greenhouse, usually by the time you realize that you have a problem it’s already taken a toll on your crop.

Following up on the concept of monitoring, I reached out to Dr. Jacques White, the executive director of Long Live the Kings, an organization dedicated to restoring wild salmon in the Pacific Northwest. Obviously, you can’t monitor access to a river, but you certainly can see the effects of fertilizer runoff, chemicals and pesticides into the areas where fish live and eventually, return to spawn.

“Because salmon travel such extraordinary long distances through rivers, streams, estuaries and into oceans they are one of the best health indicators for people. If salmon aren’t doing well, then we should think about whether people should be drinking or using that same water. The salmon population in the area around Puget Sound is not doing well.”

We talked a bit more about pesticides in general and Dr. White summed up the essence of the entire indoor-outdoor farming and pesticides debate succinctly.

“We have the ability to control what kinds of pesticides we put in our water and how much pesticides we put in our water.”

If you extrapolate that thought, the same applies to agriculture. Greenhouse farming, while subject to some problems not endemic to outdoor farming, quite simply puts a lot fewer chemicals in the air we breathe, the water we drink and the food we eat.

Cannabusiness Sustainability

Environmental Sustainability in Cultivation: Part 2

By Carl Silverberg
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The first article of this series discussed resource management for cannabis growers. In this second piece of the series on how indoor farming has a reduced impact on the environment, we’re going to look at land use & conservation. There are really two aspects and we have to be up front and acknowledge that while our focus is on legal cannabis farming, there’s a significant illegal industry which exists and is not subject to any environmental regulation.

“Streams in Mendocino run dry during the marijuana growing season impacting Coho salmon and steelhead trout who lay their eggs in the region’s waterways.” One biologist reported seeing “dead steelhead and Coho on a regular basis in late August and September, usually due to water reduction or elimination from extensive marijuana farming.” The quotes are from an extensive article on cannabis land use by Jessica Owley in the U.C. Davis Law Review.The concept that land will stay in its natural state is a mixture of idealism and reality.

This is going to continue until it’s more profitable to go legit. For this article, we’re going to focus on the legitimate cannabis grower. On the land use side, we usually hear four main reasons for indoor growing: remaining land can stay in its natural state, fewer space usually translates to fewer waste, you conserve land and natural resources when you don’t use fossil fuels, greenhouses can be placed anywhere.

The concept that land will stay in its natural state is a mixture of idealism and reality. Just because someone only has to farm five acres of land instead of one hundred acres doesn’t necessarily mean they’re going to leave the rest in its pristine natural state. Granted the footprint for automated greenhouses is significantly less but the key is what happens to that extra space. Assuming that it will all be preserved in its natural state isn’t realistic. What is realistic is the fact that a developer may not want to build tract houses abutting a commercial greenhouse operation. If they do, likely there’s going to be more land set aside for green space than if a farm was sold outright and a series of new homes were plunked down as if it were a Monopoly board.

Combined with workforce development program funding, urban indoor farming is getting more attractive every day.That’s not the same kind of issue in urban areas where the situation is different. Despite the economic boom of the past ten years, not every neighborhood benefitted. The smart ones took creative approaches. Gotham Greens started in Greenpoint, Brooklyn and has expanded to Chicago as well. “In early 2014, Gotham Greens opened its second greenhouse, located on the rooftop of Whole Foods Market’s flagship Brooklyn store, which was the first ever commercial scale greenhouse integrated into a supermarket.”

Green City Growers in Cleveland’s Central neighborhood is another example. “Situated on a 10-acre inner-city site that was once urban blight, the greenhouse—with 3.25 acres under glass–now serves as a vibrant anchor for the surrounding neighborhood.”

The beauty of greenhouse systems even those without greenhouse software, is they can be built anywhere because the environmental concerns of potentially contaminated soil don’t exist. The federal government as well as state and local governments offer a myriad of financial assistance programs to encourage growers to develop operations in their areas. Combined with workforce development program funding, urban indoor farming is getting more attractive every day.

As for the argument that greenhouses save energy and fossil fuels, I think we can agree that it’s pretty difficult to operate a thousand-acre farm using solar power. To their credit, last year John Deere unveiled a tractor that will allow farmers to run it as a fully autonomous vehicle to groom their fields while laying out and retracting the 1 kilometer long onboard extension cord along the way. It’s a start although I’ll admit to my own problems operating an electric mower without cutting the power cord.

In a 2017 article, Kurt Benke and Bruce Tomkins stated, “Transportation costs can be eliminated due to proximity to the consumer, all-year-round production can be programmed on a demand basis, and plant-growing conditions can be optimized to maximize yield by fine-tuning temperature, humidity, and lighting conditions. Indoor farming in a controlled environment also requires much less water than outdoor farming because there is recycling of gray water and less evaporation.”

The overall trend on fossil fuel reduction was verified this week when the Department of Energy announced that renewables passed coal for the first time in U.S. history.  And on the water issue, Ms. Owley had a salient point for cannabis growers. “The federal government will not allow federal irrigation water to be used to grow marijuana anywhere, even in states where cultivation is legal.” That’s not a minor detail and it’s why outdoor farming of cannabis is going to be limited in areas where water resources and water rights are hotly debated.

Cannabusiness Sustainability

Environmental Sustainability in Cultivation: Part 1

By Carl Silverberg
4 Comments

Core values often get wrapped into buzzwords such as sustainability, locally sourced and organic. In the first part of a series of four articles exploring greenhouses and the environment, we’re going to take a look at indoor vs. outdoor farming in terms of resource management.

Full disclosure; I love the fact that I can eat fresh blueberries in February when my bushes outside are just sticks. Is there a better way to do it than trucking the berries from the farm to a distribution plant to the airport, where they’re flown from the airport to a distribution center, to the grocery store and finally to my kitchen table? That’s a lot of trucking and a lot of energy being wasted for my $3.99 pint of blueberries.The largest generation in the history of the country is demanding more locally grown, sustainable and organic food. 

If those same blueberries were grown at a local greenhouse then trucked from the greenhouse directly to the grocery store, that would save diesel fuel and a lot of carbon emissions. People who can only afford to live near a highway, a port or an airport don’t need to ask a pulmonary specialist why their family has a higher rate of COPD than a family who lives on a cul-de-sac in the suburbs.

Fact: 55% of vegetables in the U.S. are grown under cover. The same energy saving principles apply to indoor cannabis and the reasons are consumer driven and producer driven. The largest generation in the history of the country is demanding more locally grown, sustainable and organic food. They want it for themselves and they want it for their kids.

The rapid proliferation of greenhouses over the past ten years is no coincidence. Millennials are forcing changes: organic fruit and vegetables now account for almost 15% of the produce market. A CNN poll last month revealed that 8 of 10 of registered Democrats listed climate change as a “very important” priority for presidential candidates. The issue is not party I.D.; the issue is that a large chunk of Americans are saying they’re worried about the direct and indirect impacts of climate change, such as increased flooding and wildfires.

So how does the consumer side tie into the cannabis industry? Consumers like doing business with companies who share their values. The hard part is balancing consumer values with investor values, which is why many indoor growers are turning to cultivation management platforms to help them satisfy both constituencies. They get the efficiency and they get to show their customers that they are good stewards of their environment. The goal is to catch things before it’s too late to save the plants. If you do that, you save the labor it costs to fix the problem, the labor and the expense of throwing away plants and you reduce pesticide and chemical usage. When that happens, your greenhouse makes more money and shows your customers you care about their values.

The indoor change is happening rapidly because people realize that technology is driving increased revenue while core consumer values are demanding less water waste, fewer pesticides, herbicides and fertilizers.Let’s add some more facts to the indoor-outdoor argument. According to an NCBI study of lettuce growing, “hydroponic lettuce production had an estimated water demand of 20 liters/kg, while conventional lettuce production had an estimated water demand of 250 liters/kg.”  Even if the ratio is only 10:1, that’s a huge impact on a precious resource.

Looking at the pesticide issue, people often forget about the direct impact on people who farm. “Rates in the agricultural industry are the highest of any industrial sector and pesticide-related skin conditions represent between 15 and 25% of pesticide illness reports,” a 2016 article in The Journal of Cogent Medicine states. Given the recent reports about the chemicals in Roundup, do we even need to continue the conversation and talk about the effects of fertilizer?

I’ll finish up with a quote from a former grower. “The estimates I saw were in the range of between 25%-40% of produce being lost with outdoor farming while most greenhouse growers operate with a 10% loss ratio.”

The indoor change is happening rapidly because people realize that technology is driving increased revenue while core consumer values are demanding less water waste, fewer pesticides, herbicides and fertilizers. Lastly, most Americans simply have a moral aversion to seeing farms throw away food when so many other people are lined up at food banks.

Food processing and sanitation

Sanitation Starting Points: More Than Sweeping the Floors and Wiping Down the Table

By Ellice Ogle
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Food processing and sanitation

Sanitation is not just sweeping the floors and wiping down the table – sanitation has a wide-ranging function in a cannabis food manufacturing facility. For example, sanitation covers the employees (and unwanted pests), food-contact equipment (and non-food-contact equipment), trash disposal (including sewage), and more. Ultimately, sanitation systems maintain a clean environment to prevent foodborne illness from affecting human health. Fortunately, there are resources and tools to ease into establishing a robust sanitation program.

Overall, the main goal of sanitation is to produce safe food, to keep consumers healthy and safe from foodborne illness. With the cannabis industry growing and gaining legalization, cannabis reaches a larger, wider audience. This population includes consumers most vulnerable to foodborne illness such as people with immunocompromised systems, the elderly, the pregnant, or the young. These consumers, and all consumers, need and deserve safe cannabis products every experience.

FDAlogoTo produce safe food, food manufacturing facilities in the United States must at least follow the Food and Drug Administration (FDA)’s Code of Federal Regulations Title 21 Chapter I Subchapter B Part 117, current good manufacturing practice, hazard analysis, and risk-based preventive controls for human food. Although cannabis is currently not federally regulated, these regulations are still relevant for a cannabis food manufacturing facility since the same basic principles still apply. Also, these regulations are a good resource to simplify a comprehensive sanitation program into more manageable components, between sanitary operations and sanitary facilities. With more manageable components, the transition is smoother to then identify the appropriate tools that will achieve a thorough sanitation program.

Sanitary operations

1) General maintenance of the facilities: The buildings and fixtures of the food manufacturing facility cover a lot of ground – hiring a maintenance team will divide the responsibility, ensuring the entire facility can be maintained in a clean and sanitary condition. Furthermore, a team can build out a tool like a preventative maintenance program to restrict issues from ever becoming issues.

Figure 1: Dirty Cloth Towel in Dirty “Sanitizer” Solution
Dirty Cloth Towel in Dirty “Sanitizer” Solution (an example of what NOT to do)

2) Control of the chemicals used for cleaning and sanitizing: Not all chemicals are equal – select the appropriate cleaning and sanitizing chemicals from reputable suppliers. Obtain the right knowledge and training on proper use, storage, and proper protective equipment (PPE). This ensures the safe and effective application of the chemicals in minimizing the risk of foodborne illness.

3) Pest control: Understand the environment within the facility and outside the facility. This will aid in identifying the most common or likely pests, in order to focus the pest control efforts. Keep in mind that internal pest management programs can be just as successful as hiring external pest control services.

4) Procedures for sanitation of both food-contact and non-food-contact surfaces: Developing sanitation standard operating procedures (SSOPs) provides guidance to employees on appropriate cleaning and sanitizing practices, to balance effective and efficient operations. A master sanitation schedule can control the frequency of indicated sanitation procedures.

5) Storage and handling of cleaned portable equipment and utensils: Cross contamination in storage can be minimized with tools such as controlled traffic flow, signage, training, color coding, and more.

Sanitary facilities

6) Water supply, plumbing, and sewage disposal: Routine inspections of plumbing, floor drainage, and sewage systems prevent unintended water flow and damage.

7) Toilet facilities: Clearly defining standards for the toilet facilities and setting accountability to everyone who uses them will ensure that the toilet facilities are not a source of contamination for the food products.

Food processing and sanitation
PPE for all employees at every stage of processing is essential

8) Hand-washing facilities: Good manufacturing practices (GMPs) include proper hand washing and proper hand washing starts with suitable hand-washing facilities. For example, frequent checks on running water, hand soap, and single use towels ensure that all hands are clean and ready to produce safe food.

9) Trash disposal: While trash can be a source of cross contamination, trash can also attract and harbor pests. Scheduling regular trash disposal and controlling traffic flow of waste are two ways to minimize the risk of cross contamination from trash.

Bonus

Even after meeting these requirements, sanitation programs can be more sophisticated. An example is to institute an environmental monitoring program to verify and validate that the sanitation program is effective. Another example is in identifying and measuring key performance indicators (KPIs) within the sanitation program that can improve not just the sanitation processes, but the operations as a whole. Principally, sanitation is cleanliness on the most basic level, but waste management can encompass sanitation and grow into a larger discussion on sustainability. All in all, sanitation programs must reshape and evolve alongside the company growth.

Sanitation is interwoven throughout the food manufacturing process; sanitation is not a single task to be carried out by a sole individual. As such, it is beneficial to incorporate sanitation practices into cannabis food manufacturing processes from the beginning. Protect your brand from product rework or recalls and, most importantly, protect your consumers from foodborne illness, by practicing proper sanitation.

HACCP

Implementing a HACCP Plan to Address Audit Concerns in the Infused Market

By Daniel Erickson
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HACCP

The increasing appeal and public acceptance of medical and recreational cannabis has increased the focus on the possible food safety hazards of cannabis-infused products. Foodborne illnesses from edible consumption have become more commonplace, causing auditors to focus on the various stages of the supply chain to ensure that companies are identifying and mitigating risks throughout their operations. Hazard Analysis and Critical Control Points (HACCP) plans developed and monitored within a cannabis ERP software solution play an essential role in reducing common hazards in a market currently lacking federal regulation.

What are cannabis-infused products?

Cannabis infusions come in a variety of forms including edibles (food and beverages), tinctures (drops applied in the mouth), sprays (applied under the tongue), powders (dissolved into liquids) and inhalers. Manufacturing of these products resembles farm-to-fork manufacturing processes common in the food and beverage industry, in which best practices for compliance with food safety regulations have been established. Anticipated regulations in the seed-to-sale marketplace and consumer expectations are driving cannabis infused product manufacturers to adopt safety initiatives to address audit concerns.

What are auditors targeting in the cannabis space?

The cannabis auditing landscape encompasses several areas of focus to ensure companies have standard operating procedures (SOP’s) in place. These areas include:

  • Regulatory compliance – meeting state and local jurisdictional requirements
  • Storage and product release – identifying, storing and securing products properly
  • Seed-to-sale traceability –  lot numbers and plant identifiers
  • Product development – including risk analysis and release
  • Accurate labeling –  allergen statements and potency
  • Product sampling – pathogenic indicator and heavy metal testing
  • Water and air quality –  accounting for residual solvents, yeasts and mold
  • Pest control – pesticides and contamination

In addition, auditors commonly access the reliability of suppliers, quality of ingredients, sanitary handling of materials, cleanliness of facilities, product testing and cross-contamination concerns in the food and beverage industry, making these also important in cannabis manufacturers’ safety plans.

How a HACCP plan can help

HACCPWhether you are cultivating, harvesting, extracting or infusing cannabis into edible products, it is important to engage in proactive measures in hazard management, which include a HACCP plan developed by a company’s safety team. A HACCP plan provides effective procedures that protect consumers from hazards inherent in the production and distribution of cannabis-infused products – including biological, chemical and physical dangers. With the lack of federal regulation in the marketplace, it is recommended that companies adopt these best practices to reduce the severity and likelihood of compromised food safety.

Automating processes and documenting critical control points within an ERP solution prevents hazards before food safety is compromised. Parameters determined within the ERP system are utilized for identification of potential hazards before further contamination can occur. Applying best practices historically used by food and beverage manufacturers provides an enhanced level of food safety protocols to ensure quality, consistency and safety of consumables.

Hazards of cannabis products by life-cycle and production stage

Since the identification of hazards is the first step in HACCP plan development, it is important to identify potential issues at each stage. For cannabis-infused products, these include cultivation, harvesting, extraction and edibles production. Auditors expect detailed documentation of HACCP steps taken to mitigate hazards through the entire seed-to-sale process, taking into account transactions of cannabis co-products and finished goods at any stage.

Cultivation– In this stage, pesticides, pest contamination and heavy metals are of concern and should be adequately addressed. Listeria, E. coli, Salmonella and other bacteria can also be introduced during the grow cycle requiring that pathogenic indicator testing be conducted to ensure a bacteria-free environment.

Harvesting– Yeast and mold (aflatoxins) are possible during the drying and curing processes. Due to the fact that a minimal amount of moisture is optimal for prevention, testing for water activity is essential during harvesting.

Extraction – Residual solvents such as butane and ethanol are hazards to be addressed during extraction, as they are byproducts of the process and can be harmful. Each state has different allowable limits and effective testing is a necessity to prevent consumer exposure to dangerous chemical residues.

Edibles– Hazards in cannabis-infused manufacturing are similar to other food and beverage products and should be treated as such. A risk assessment should be completed for every ingredient (i.e. flour, eggs, etc.), with inherent hazards or allergens identified and a plan for addressing approved supplier lists, obtaining quality ingredients, sanitary handling of materials and cross-contamination.

GMPFollowing and documenting the HACCP plan through all of the stages is essential, including a sampling testing plan that represents the beginning, middle and end of each cannabis infused product. As the last and most important step before products are introduced to the market, finished goods testing is conducted to ensure goods are safe for consumption. All information is recorded efficiently within a streamlined ERP solution that provides real-time data to stakeholders across the organization.

Besides hazards that are specific to each stage in the manufacturing of cannabis-infused products, there are recurring common procedures throughout the seed-to-sale process that can be addressed using current Good Manufacturing Practices (cGMP’s).  cGMPs provide preventative measures for clean work environments, training, establishing SOPs, detecting product deviations and maintaining reliable testing. Ensuring that employees are knowledgeable of potential hazards throughout the stages is essential.Lacking, inadequate or undocumented training in these areas are red flags for auditors who subscribe to the philosophy of “if it isn’t documented, it didn’t happen.” Training, re-training (if necessary) and documented information contained within cannabis ERP ensures that companies are audit-ready. 

Labeling

The importance of proper labeling in the cannabis space cannot be understated as it is a key issue related to product inconsistency in the marketplace. Similar to the food and beverage industry, accurate package labeling, including ingredient and allergen statements, should reflect the product’s contents. Adequate labeling to identify cannabis products and detailed dosing information is essential as unintentional ingestion is a reportable foodborne illness. Integrating an ERP solution with quality control checks and following best practices ensures product labeling remains compliant and transparent in the marketplace.

Due to the inherent hazards of cannabis-infused products, it’s necessary for savvy cannabis companies to employ the proper tools to keep their products and consumers safe. Utilizing an ERP solution that effectively manages HACCP plans meets auditing requirements and helps to keep cannabis operations one step ahead of the competition.

Water Policy in California: Six Key Takeaways from the State Water Board’s New Cannabis Cultivation Policy

By Amy Steinfeld
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Cannabis is the most highly regulated crop in California, and the state just added another layer of regulation. This article breaks down the State Water Resources Control Board’s (SWRCB) recently updated Cannabis Cultivation Policy – Principles and Guidelines for Cannabis Cultivation (“Policy”) into six key takeaways.1 These guidelines impose new rules on cannabis cultivation activities that have the potential to impact a watercourse (stream, creek, river or lake). Most of these rules apply to cultivation of sun-grown cannabis, which is currently allowed in some form in 12 counties. Compliance with these new requirements will be implemented through the CalCannabis Cultivation Licensing Program.

  1. When developing farmland, hillsides should be avoided and erosion must be controlled.

The Policy provides specific rules for growing pot on undisturbed land. To prevent erosion, numerous limitations are placed on earthmoving and activities in sensitive areas, and cultivators are not allowed to grade hillsides that exceed a 50% slope.2

Cultivation prepping activities must minimize grading, dust, soil disturbance, erosion, and impacts on habitat, especially during the winter season.3 No vehicles or heavy equipment may be used within a riparian setback4 or watercourse,5 and cultivators must avoid damaging native riparian vegetation6 and oak woodlands.7 All farm equipment, fuel, and hazardous materials must be carefully stored away from creeks and sensitive habitat.8 The Policy also governs road construction.9

  1. Cultivators should avoid work in or near a surface waterbody.10

If a cultivator’s activities impact a river, stream, or lake, they must consult with the California Department of Fish and Wildlife (CDFW).11 Cultivators must maintain minimum riparian setbacks for all cannabis activities, including grading and ancillary farm facilities. Before grading land, a biologist must identify any sensitive flora or fauna, and if any is located, consult with CDFW and provide a report to the Regional Board.12 No irrigation runoff, tailwater, chemicals or plant waste can be discharged to a waterbody.13 Diversion facilities for the irrigation of cannabis may not block fish passage, upstream or downstream, and must be fitted with a CDFW-approved fish screen; new facilities are subject to all applicable permits and approvals.

  1. During the dry season, cultivators may not use surface water.

The use of surface water supplies in California requires a valid water right and the use of water for cannabis cultivation is no different.14 Anyone seeking to appropriate “water flowing in a known and defined channel” or from a watercourse must apply to the SWRCB and obtain a permit or license.15 Alternatively, a landowner whose property is adjacent to a watercourse may have a riparian right to divert the water for use on her land. Riparian users do not need permission from the SWRCB to divert water, but they must report water use annually.16

The biggest obstacle that growers face under this Policy is that they cannot divert anysurface water during the dry season—the growing season (April 1 through Oct. 31). It should be noted:

  • The seasonal prohibition of surface water diversion applies regardless of the nature of the water right or what has been historically used to irrigate other crops.
  • During the dry period, cultivators may only irrigate using stored water (see no. 5 below) or groundwater.
  • It remains to be seen whether a legal challenge will be brought against the state for their draconian prohibitions on irrigating cannabis during the six-month growing season. Because this prohibition applies to all watersheds in California, singles out one low-water use crop, and ignores established water rights, it is overly broad and may constitute a constitutional “taking” of property rights.
  1. During the wet season, surface water diversions must be monitored closely.

Cannabis-specific restrictions also apply during the wet season. From Nov. 1 to March 31, cultivators must comply with instream flow requirements and check in with the state daily. All surface water diversions for cannabis are subject to “Numeric and Narrative Instream Flow Requirements,” to protect flows needed for fish migration and spawning. To ensure diversions do not adversely impact fish flows, cultivators must also “maintain a minimum bypass of at least 50% of the streamflow.”17,18

While valid appropriative right holders may divert more than 10 gal./min. for cannabis irrigation during the wet season, riparian right holders are not allowed to exceed that diversion rate.19 All cultivators (including small diverters <10 acre-feet (“AF”)/yr) are required to employ water-saving irrigation methods, install measuring devices to track diversions daily, and maintain records on-site for at least five years.20 Cultivators must inspect and repair their water delivery system for leaks monthly,21 and inspect sprinklers and mainlines weekly to prevent runoff.22

  1. Cannabis cultivators may obtain a new water storage right for use during the dry season.

To address dry season irrigation limitations, cultivators are urged to store water offstream during the wet season, including rainwater, for dry season use. Growers may not rely on onstreamstorage reservoirs, except if they have an existing permitted reservoir in place prior to Oct. 31, 2017.23 Alternatively, small growers (storage is capped at 6.6 AF/yr) may benefit from the new Cannabis SIUR Program, an expedited process for cultivators who divert from a surface water source to develop and install storage offstream. Only diverters with a valid water right that allows for diversion to storage between Nov. 1 and March 31 qualify.

  1. Groundwater is less regulated, but cultivators should avoid drilling or using wells near waterbodies.

Groundwater is generally the recommended water supply for cannabis because, unlike surface water, it may be used during the dry season and is not subject to many of the restrictions listed above. It should be noted however:

  • Many groundwater basins are now governed by California’s Sustainable Groundwater Management Act (“SGMA”), which requires water agencies to halt overdraft and restore balanced levels of groundwater pumping from certain basins. Thus, SGMA may result in future pumping cutbacks or pumping assessments.
  • In some counties, moratoriums and restrictions on drilling new wells are on the rise.
  • Under this Policy, the state may step in to restrict groundwater pumping in the dry season in watersheds where there are large numbers of cannabis groundwater, wells located close to streams, and areas of high surface water-groundwater connectivity.24

In short, groundwater pumpers are at risk of cutback if the state deems it necessary to maintain nearby creek flows.Noncompliance can bring lofty fines, revocation of a grower’s cultivation license, or prosecution

Final Takeaways

This cannabis policy presents one of California’s most complex regulatory schemes to date. Before investing in a property, one must understand this Policy and have a robust understanding of the water rights and hydrology associated with the cultivation site. Growers looking to reduce permitting time and costs should invest in relatively flat, historically cultivated land with existing wells and ample groundwater supplies, or alternatively, grow indoors.

This article attempts to synthesize the maze of water supply and water quality regulations that make compliance exceedingly difficult; more detailed information can be found here. Noncompliance can bring lofty fines, revocation of a grower’s cultivation license, or prosecution. Growers are encouraged to contact a hydrologist and water lawyer before making major investments and to designate a water compliance officer to monitor and track all water diversions and water used for irrigation. Growers should also consult with their local jurisdiction regarding water use restrictions and stream setbacks before moving any dirt or planting cannabis.


References

  1. The Policy is available at: https://www.waterboards.ca.gov/water_issues/programs/cannabis/cannabis_policy.html (will go into effect on or before April 16, 2019.)
  2. Policy, Appendix A, Section 2, Term 4. The Policy defines “Qualified Professional” as a: California-Licensed Professional Geologist, including Certified Hydrogeologist and Certified Engineering Geologist, California-Licensed Geotechnical Engineer, and Professional Hydrologist. (Policy, Definition 72, p. 11.)
  3. Policy, Appendix A, Section 2, Terms 4 and 10.
  4. Policy, Appendix A, Section 2, Term 3.
  5. Policy, Appendix A, Section 2, Term 40.
  6. Policy, Appendix A, Section 2, Term 33.
  7. Policy, Appendix A, Section 2, Term 34.
  8. Policy, Appendix A, Section 2, Term 7.
  9. Policy, Appendix A, Section 2, Terms 15 to 29.
  10. Policy, Appendix A, Section 1, Term No. 41.
  11. Policy, Appendix A, Section 1, Term No. 3; see also 1602.
  12. Policy, Appendix A, Section 1, Term No. 10.
  13. Policy, Appendix A, Section 1, Term No. 326.
  14. Policy, Appendix A, Section 2, Term 69.
  15. Wat. Code §1225; See alsoWat. Code §1201 [providing that the state shall have jurisdiction over, “[a]ll water flowing in any natural channel” except water that is appropriated or being used for beneficial purpose upon land riparian to the channel.”]
  16. Wat. Code §§ 5100–02.
  17. Policy, p. 12.
  18. Policy, Attachment A, pp. 60, 63.
  19. Policy, Section 2, Term 78.
  20. Policy, Section 2, Term 82.
  21. Policy, Section 2, Term 95.
  22. Policy, Section 2, Term 99.
  23. Policy, Section 2, Term 79.
  24. Policy, p. 11.

Heavy Metals Testing: Methods, Strategies & Sampling

By Charles Deibel
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Editor’s Note: The following is based on research and studies performed in their Santa Cruz Lab, with contributions from Mikhail Gadomski, Lab Manager, Ryan Maus Technical Services Analyst, Laurie Post, Director of Food Safety & Compliance, and Charles Deibel, President Deibel Cannabis Labs.


Heavy metals are common environmental contaminants resulting from human industrial activities such as mining operations, industrial waste, automotive emissions, coal fired power plants and farm/house hold water run-off. They affect the water and soil, and become concentrated in plants, animals, pesticides and the sediments used to make fertilizers. They can also be present in low quality glass or plastic packaging materials that can leach into the final cannabis product upon contact. The inputs used by cultivators that can be contaminated with heavy metals include fertilizers, growing media, air, water and even the clone/plant itself.

The four heavy metals tested in the cannabis industry are lead, arsenic, mercury and cadmium. The California Bureau of Cannabis Control (BCC) mandates heavy metals testing for all three categories of cannabis products (inhalable cannabis, inhalable cannabis products and other cannabis and cannabis products) starting December 31, 2018. On an ongoing basis, we recommend cultivators test for the regulated heavy metals in R&D samples any time there are changes in a growing process including changes to growing media, cannabis strains, a water system or source, packaging materials and fertilizers or pesticides. Cultivators should test the soil, nutrient medium, water and any new clones or plants for heavy metals. Pre-qualifying a new packaging material supplier or a water source prior to use is a proactive approach that could bypass issues with finished product.

Testing Strategies

The best approach to heavy metal detection is the use of an instrument called an Inductively Coupled Plasma Mass Spectrometry (ICP-MS). There are many other instruments that can test for heavy metals, but in order to achieve the very low detection limits imposed by most states including California, the detector must be the ICP-MS. Prior to detection using ICP-MS, cannabis and cannabis related products go through a sample preparation stage consisting of some form of digestion to completely break down the complex matrix and extract the heavy metals for analysis. This two-step process is relatively fast and can be done in a single day, however, the instruments used to perform the digestion are usually the limiting step as the digesters run in a batch of 8-16 samples over a 2-hour period.

Only trace amounts of heavy metals are allowed by California’s BCC in cannabis and cannabis products. A highly sensitive detection system finds these trace amounts and also allows troubleshooting when a product is found to be out of specification.

For example, during the course of testing, we have seen lead levels exceed the BCC’s allowable limit of 0.5 ppm in resin from plastic vape cartridges. An investigation determined that the plastic used to make the vape cartridge was the source of the excessive lead levels. Even if a concentrate passes the limits at the time of sampling, the concern is that over time, the lead leached from the plastic into the resin, increasing the concentration of heavy metals to unsafe levels.

Getting a Representative Sample

The ability to detect trace levels of heavy metals is based on the sample size and how well the sample represents the entire batch. The current California recommended amount of sample is 1 gram of product per batch.  Batch sizes can vary but cannot be larger than 50 pounds of flower. There is no upper limit to the batch sizes for other inhalable cannabis products (Category II).

It is entirely likely that two different 1 gram samples of flower can have two different results for heavy metals because of how small a sample is collected compared to an entire batch. In addition, has the entire plant evenly collected and concentrated the heavy metals into every square inch of it’s leaves? No, probably not. In fact, preliminary research in leafy greens shows that heavy metals are not evenly distributed in a plant. Results from soil testing can also be inconsistent due to clumping or granularity. Heavy metals are not equally distributed within a lot of soil and the one small sample that is taken may not represent the entire batch. That is why it is imperative to take a “random” sample by collecting several smaller samples from different areas of the entire batch, combining them, and taking a 1 g sample from this composite for analysis.


References

California Cannabis CPA. 12/18/2018.  “What to Know About California’s Cannabis Testing Requirements”. https://www.californiacannabiscpa.com/blog/what-to-know-about-californias-cannabis-testing-requirements. Accessed January 10, 2019.

Citterio, S., A. Santagostino, P. Fumagalli, N. Prato, P. Ranalli and S. Sgorbati. 2003.  Heavy metal tolerance and accumulation of Cd, Cr and Ni by Cannabis sativa L.. Plant and Soil 256: 243–252.

Handwerk, B. 2015.  “Modern Marijuana Is Often Laced With Heavy Metals and Fungus.” Smithsonian.com. https://www.smithsonianmag.com/science-nature/modern-marijuana-more-potent-often-laced-heavy-metals-and-fungus-180954696/

Linger, P.  J. Mussig, H. Fischer, J. Kobert. 2002.  Industrial hemp (Cannabis sativa L.) growing on heavy metal contaminated soil: fibre quality and phytoremediation potential. Ind. Crops Prod. 11, 73–84.

McPartland, J. and K. J McKernan. 2017.  “Contaminants of Concern in Cannabis: Microbes, Heavy Metals and Pesticides”.  In: S. Chandra et al. (Eds.) Cannabis sativa L. – Botany and Biotechnology.  Springer International Publishing AG. P. 466-467.  https://www.researchgate.net/publication/318020615_Contaminants_of_Concern_in_Cannabis_Microbes_Heavy_Metals_and_Pesticides.  Accessed January 10, 2019.

Sidhu, G.P.S.  2016.  Heavy metal toxicity in soils: sources, remediation technologies and challenges.   Adv Plants AgricRes. 5(1):445‒446.