Wednesday, 14 December 2016 10:50 Published in Blog

SC Labs has spent considerable time and resources to develop a comprehensive microbiology program for the Cannabis industry. We have implemented the same proven technology and methods that have become standard throughout the food and agricultural testing industries.

We use a combination of 3M Petrifilm and qPCR-based assays to identify and quantify microbiological contamination in Cannabis. Our microbiological panel is a powerful tool for customers to determine the safety and quality of their cannabis product. It includes five separate tests for Total Yeast and Mold, Total Aerobic Plate Count (APC), Total Coliform Bacteria, EColi, Pseudomonas, and Salmonella. These tests are required by most states and jurisdictions which have implemented mandatory microbiological testing of cannabis.

The Total Yeast and Mold and the Total Aerobic Plate Count portion of the panel measure the overall fungal and bacterial loads respectively on the sample we tested. These panels do not distinguish between harmful and benign organisms but give a great indication of the overall microbiological growth on the product. In the food or agricultural industry, the tests are used to estimate shelf life and overall cleanliness. The Total Coliform Bacteria test measures a specific family of bacteria that are considered an overall indicator of sanitary coliform. While coliform bacteria are not necessarily harmful themselves, they are common in aquatic environments, soil, and in the feces of warm-blooded animals. Because of this, they are often used as a potential indicator of contamination by pathogenic fecal organisms. Some detection of organisms on these tests is considered normal but abnormally high levels of contamination should lead to further investigation.


The E Coli, Pseudomonas, and Salmonella tests identify and measure specific species or families of bacteria that are commonly found on agricultural products and have the potential to cause illness. E Coli are common bacteria found in the intestines of warm-blooded animals. Many strains of E Coli are benign but some have the potential to cause illness and are responsible for many cases of food poisoning. SC Labs finds E Coli contamination on approximately 4% of samples tested. Pseudomonas is a very common bacterium and is widespread in the environment and flourishes in moist environments. Most species are benign but some species are known animal and plant pathogens. Pseudomonas aeruginosa is responsible for many hospital-based infections. Some species of Salmonella can cause food poisoning as well as certain fevers. Salmonella is another fecal based bacteria that is less common on herbal cannabis because of its’ sensitivity to UV light but can infect food or cannabis that has been processed under unsanitary conditions.

The AHP Monograph has become the preferred guidance document for best practices in the cannabis industry and is often cited by regulators and industry trade groups. The monograph contains recommended levels of microbiological contamination. These limits are not intended to be used as pass/fail tolerances for most of the tests but rather to guide cultivators looking to maintain best practices in the production of cannabis.

However, many regulators have taken a stricter approach to regulating microbiological contamination on cannabis. Many states and municipalities, including the City of Berkeley, have set strict tolerances for all five tests on the microbiological panel. An analysis of SC Labs’ historical data indicates that even with these strict tolerances greater than 80% of California cannabis still passes the City of Berkeley’s limits (See Below). However, most of the failing cannabis does not contain harmful organisms and should still be perfectly safe for human consumption.

SC Labs recommends a more common sense approach to the interpretation of microbiological testing that is more in line with the way the tests are implemented in the food, agriculture, and herbal products industries. We recommend that batches that test positive for E Coli and Salmonella be destroyed or remediated (after a confirmation test of course) due to the potential for acute illness associated with the presence of even a small amount of these pathogens. We also recommend that batches that test over 1,000 cfu/g of Coliform bacteria or 10,000 cfu/g of Pseudomonas be sterilized or remediated as well due to the indication of unsanitary conditions. However, we do not recommend an automatic fail for crops that test over 100,000 cfu/g for APC or Total Yeast and Mold. We strongly advise producers that do test over these limits to perform conformational testing on other samples from the batch to confirm the elevated levels and take action to lower them.

We also strongly recommend that a cultivator or producer that tests over any of these limits perform a comprehensive investigation to determine the source of their contamination. SC Labs can provide environmental swabs or can test fertilizer or foliar sprays to try to identify and reduce contamination sources.

Without the ability to use certain pesticides to battle pests or disease when cultivating cannabis, many producers have turned to foliar and soil application of beneficial fungus or bacteria. Applying these microorganisms is a great way to protect the plant from disease but also raises the levels of bacteria and fungus on the plant which could be reflected with elevated APC and Total Yeast and Mold counts on the microbiological panel. This puts cultivators in states that set limits for these tests in a tough position. Even though these beneficial microbes may be entirely benign, they could cause the cultivator or producer to fail a state mandated test. Under these circumstances, SC Labs recommends growers avoid foliar applications of beneficial microbes at the end of the grow cycle since many of the organisms are UV sensitive and will die off when given enough time. It's also important to remember that a very common source of contamination takes place during processing. During harvest, care should be taken to not let plant material contact soil and during drying and processing sanitation is extremely important.

It should be noted that poorly brewed compost tea and fecal-based fertilizers can often contain pathogenic organisms and should be tested regularly to avoid applying contaminated foliar sprays to cannabis plants.


Thursday, 08 December 2016 10:11 Published in Blog

The Emerald Cup and SC Labs, along with many other members of the Cannabis Community, have decided to put together a last-minute fundraiser to support the water protectors of the Standing Rock Sioux Tribe.  Please watch for donation stations at booths all around The Emerald Cup this weekend and help us show the world that the Cannabis Community Stands with Standing Rock! 

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