As above, so below: who is responsible for cannabis soil testing?

Cannabis soil testing issues: cannabis sprout grows from soil.

Cannabis consumers buying products at legal dispensaries trust that the product is safe to consume. But despite regulations, sometimes product ends up contaminated–just like that one time the spinach got E.coli. A few cannabis farms in Northern Washington are learning what happens when pesticides seep into the soil.

Washington cannabis operations along the Okanogan River were forced to shut down in Spring following routine soil testing. The tests showed residual signs of DDE, a now-illegal pesticide that can negatively impact the liver, immune system, and central nervous system when inhaled. Five licensees have been affected by the contamination, the result of apple farming on the land long before the cannabis companies assumed the property.

The public asked for the Liquor Control Board (LCB) update on the matter at a recent board meeting, and Enforcement and Education Director Chandra Wax responded.

“We recognize the significant impact this has on licensees and the risk this poses to the public,” Wax said in the board meeting. “We are acting responsibly, swiftly, and intentionally. Our goal is to ensure cannabis products are safe and licensees and stakeholders are informed as updates are available. We continue pesticide investigations statewide.”

Results from soil, water, and product testing in Washington

A week after the original DDE test results, the LCB returned to take additional soil samples. The tests were sent to the Department of Ecology and are not complete. But the department reported that as results currently stand, samples contain DDE/DDT, lead, and arsenic levels above state standards.

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The agency also gathered 124 additional water and product samples to test through the Department of Agriculture. This included 54 samples of foliage (or leaves and flower), 40 rosin and oil, and three water samples.

Water tested clean, but 66 of 97 samples of foliage and extracts contained DDE, and 44 tested beyond the allowed actionable limits. Of the foliage samples, 24 could reach actionable limits if extracted. The Department of Agriculture also detected 17 additional pesticides, with 23 samples above limits.

Products that didn’t test above actionable limits are no longer “on hold” by the LCB. However, some of these products cannot be extracted due to concentration of DDE levels. One of the five affected cannabis companies is free of the administrative hold. Farmers in other states might consider testing their soil as the four remaining farms wait in limbo, many losing the whole season of profits. One might wonder why it took so long to detect the DDE.

“Farmers in the region who suspected that there may be DDE in the soil from old orchard spraying of DDT did have their soils tested,” LCB communications director Brian Smith explained to GreenState, “It doesn’t have to be an authorized cannabis lab.  Any farmer in that region also does not have to use the existing soil. Many chose to truck in soil or use elevated beds to be safe and avoid this issue altogether.” 

The state is not likely to adjust the list of monitored pesticides to include DDE/DDT or add soil testing to the licensing process according to Smith. Affected areas cover just five square miles of the state. Additionally, the Department of Ecology continues testing and monitoring lead and arsenic levels in Washington soil. Farmers and residents interested in having their soil analyzed can reach out to the department directly.

How do other states monitor soil?

Cannabis farmers go through a rigorous licensing process to legally grow the plant, and sometimes it’s expensive. Washington does not require outdoor farmers to submit or test soil samples before applying. For the four farmers awaiting their fate along the Okanogan River, testing soil before investing in the infrastructure to grow would have avoided the whole situation.

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In California, the Department of Cannabis Control (DCC) oversees cannabis regulation. DCC Communications analyst Moorea Warren responded to an inquiry on soil testing via email. She explained that product testing is required, but the state does not test soil or water at cannabis cultivation sites.

“Concerns about soil or water contamination would most likely be investigated by the California Department of Pesticide Regulation and the State Water Resources Control Board at the state level, agricultural commissions at the local level, and the Environmental Protection Agency at the federal level,” Warren shared.

She added that city and county jurisdictions could require testing, and that all projects must adhere to the California Environmental Quality Act review to identify the environmental impact and avoid damage.

Oregon farmers also responsible soil testing

Oregon officials sing a similar tune. The Oregon Health Authority (OHA) oversees medical cannabis in the state. The Oregon Liquor and Cannabis Commission governs the adult-use program in the state. OHA public affairs specialist Afiq Hisham expanded on medical cannabis cultivation soil testing.

“Those looking to register a grow site for medical marijuana do not need to test their soil,” Hisham shared with GreenState, “With that said, whenever growers ask about soil concerns, OHA recommends the practice as a way of learning and being aware of what may be on their land. Similarly, the Oregon Liquor and Cannabis Commission (OLCC) doesn’t require any soil testing for growing recreational cannabis, though growers do need to test the plant itself.”

Despite decades of unregulated pesticide use in traditional farming, cannabis farms continue to take over the land without any regulated soil testing or assessment. The recent DDE contamination in Washington should be a wake-up call to further investigation.

Cara Wietstock is Senior Content Producer of and has been working in the cannabis space since 2011. She has covered the cannabis business beat for Ganjapreneur and The Spokesman Review. You can find her living in Bellingham, Washington with her husband, son, and a small zoo of pets.