Cannabis Testing & Pesticides – A Real Problem

Written by Enigma Valdez

As the Cannabis industry continues to emerge from the shadows, cultivators, producers, dispensaries and related businesses are required to navigate through a maze of laws and regulations that are still evolving across state and local jurisdictions. Just this past January, California has finally joined the bandwagon of legalizing recreational marijuana.

However, Donald Land, University of California, Davis, chemistry professor and chief scientific consultant of Steep Hill Labs Inc., cautions that consumers should beware. Steep Hill Labs tests cannabis in several states of the country, with extensive testing overseen by Land earlier this year. These tests were done on samples collected from 15 dispensaries through four counties, within Southern California. Land’s tests discovered 93% of samples collected tested positive for pesticides.

This may come as a stark surprise for cannabis consumers who trust whatever is on the store shelves, assuming that the federal government, U.S. Food and Drug Administration and the U.S. Department of Agriculture have tested the product for safe consumption. Land says that this is not true. “They wrongly assume it’s been tested for safety”, he states. While more stringent regulations and testing requirements are in the works for the upcoming year, cultivators in California still have a six -month grace period to sell off their current inventory.

Due to only having a year to develop a sophisticated infrastructure of licensing, taxing and regulating recreational marijuana, California state officials have realized that it is more realistic and fair to give a six month grace period to growers. Dispensaries and shops will also have six months to sell off their current cannabis inventory before they will be required to pass tests. Any cannabis harvested or manufactured after January 1, 2018, however, will require rigorous analytical testing.

The Pesticide Problem

Because cannabis is still illegal on a federal level, the Environmental Protection Agency does not have a recommended list of pesticides for cannabis growers, like they do for other kinds of farmers. States like Vermont (Vermont Agency of Agriculture) are relying on much of the work already done in other states, like California. “We’re going to rely heavily on a lot of the work California is doing with regard to on the risk assessments and health effects of the pesticides used on cannabis,” said Cary Giguere of the Vermont Agency of Agriculture.

Unlike other growers, there are no pesticides specifically designed for cannabis plants. Once again, the federal government hasn’t allowed enough testing for such pesticides to be developed. Some states have lists of approved pesticides, but more often than not, these are weak or ineffective. In desperate measures, growers have turned to dangerous chemicals that may even be illegal to use, in order to protect their crops. These can pose a very big risk to consumers, especially when it comes to cannabis that will become edibles or will be smoked.

As medical and recreational cannabis legalization continues to sweep across the nation, each state is now faced with developing legal requirements to test for clean and safe cannabis. Each state has to require that cannabis is evaluated by specific laboratory tests that analyze and detect the presence of mold, yeast and microbial impurities. Each state has to require that cannabis is evaluated by specific laboratory tests that analyze and detect the presence of contaminants like pesticides, mold, yeast and microbial impurities.

Understanding the Scientific Approach

There are two major categories for cannabis laboratory testing requirements:

  1. Analytical chemistry – This is the science of quantitatively and qualitatively establishing the chemical makeup of a substance. This method is utilized in quantifying cannabis potency, terpene profile, and in the detection of mycotoxins, heavy metals, and residual solvents. Analytical lab testing methods are done prior to going on to microbiological testing methods.
  2. Microbiological methods – These methods dig deeper into the cannabis product’s cellular level. There, the goal is to uncover impurities, such as bacteria, mold and yeast. The methods used in this are very different from the ones used in analytical chemistry. This includes the way they are performed and also the target of the final analysis. Different state regulations will invariably result in different microbiological techniques utilized in the testing phase. While there are a number of techniques that can be utilized for detecting microbial impurities, most of these can be separated into two further categories. The first is the total yeast and mold count (TYMC), which involves the use of cell culture. Cells are grown in a favorable environment, plated and spread in a petri dish. The second category is Polymerase Chain Reaction or (PCR). This involves testing in order to determine the presence for unique DNA sequences, belonging to specific types of mold strains.

While there certainly appears to be a consensus all across the country that laboratories should definitely test for cannabis potency, residual solvents, and pesticides, the microbial testing requirements, especially for mold, vary greatly for each state. Colorado, Massachusetts, Illinois, Maine and Nevada all have language in their regulations that explicitly calls for TYMC. Oregon, however, does not have any details on test type required, other than random testing for mold. Due to the recent emergency regulations in California, the state is now testing cannabis for specific mold. (Aspergillus mold, which include A. flavus, A. fumigatus, A. terreus, A. niger) These require DNA testing, as they are too hard to differentiate on a testing plate. The differences in costs involved with testing will no doubt impact the overall costs for growers, manufacturers and ultimately consumers.

Not only that, but these issues have even gone so far as to affect the cannabis stock market. Cannabis may be illegal on a federal level, but that certainly has not stopped opportunistic businessmen and investors from making a fortune off the cannabis industry. According to The Green Market Report, Scotts Miracle-Gro is one of a handful of companies that has managed to break through and get listed on either the NASDAQ Stock Market or the New York Stock Exchange. (Cannabis Stocks Part One: The Six NYSE Traded Cannabis Stocks

Miracle-Gro surprised the industry in 2016, by announcing that it planned to invest $500 million into the industry. So far, hundreds of millions of dollars have been spent to acquire technology and hydroponics companies, as well as looking into developing pesticides specifically developed for cannabis plants. The future of cannabis testing in regards to pesticides will continue to change and evolve. There are two things that no one in the cannabis can get around and those are change and uncertainty. What is certain, though, is that with the ever present regulations tightening up on testing for pesticides, it’s important that cannabis cultivators are able to stay compliant, while at the same time doing everything they can to protect their crops.


  1. An Insider’s View: How Labs Conduct Cannabis Mold Testing
  1. Marijuana Matters: Environmental Effects of Growing Pot
  1. Cannabis Quality and Contamination Testing
  1. Cannabis Stocks Part One: The Six NYSE Traded Cannabis Stocks
  1. The Wild West of Marijuana Pesticides
  1. Advances in Analytical Chemistry
  1. Leafly Guide to Cannabis Testing State by State
  1. Bureau of Marijuana Control Proposed Text of Regulations. California Code of Regulations

About the author

Enigma Valdez

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