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Many Cannabis Crops Grown in Washington County Are Contaminated With Banned Pesticide, Regulator Finds

By Leo Bear-McGuinness

Published: Jul 12, 2023   
Cannabis crops and the sunset.

Image credit: iStock

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Many cannabis products grown in the Okanogan County area of Washington are contaminated with a banned pesticide, according to the state regulator.

In a memo to state licensees sent on July 10, the Washington State Liquor and Cannabis Board (LCB) announced the results of its investigation of cannabis grown in the Okanogan region. Out of 108 product samples submitted, 61 products (56%) tested above the 0.1 action limit for dichlorodiphenyldichloroethylene (DDE).

The LCB says it has placed a hold on each of the contaminated products and will work with the licensees to ensure the identified products are destroyed.

Banned in Washington

The LCB’s investigation follows its announcement in April that its staff had identified “a pattern of pesticide testing failures” among cannabis cultivators along the south end of the Okanogan River and north of Lake Pateros.

All 18 licensed cannabis cultivators in the area then received an email informing them that they would soon have their products, soil, and water tested for dichlorodiphenyltrichloroethane (DDT).

DDT was banned in the US in 1972 due to the threat it posed to wildlife. Over time it can break down to form DDE.

According to the LCB, there were five licensees with DDE above action limits. LCB staff called each of them on April 6, 2023, to tell them about the test results, inform them about the administrative hold that would be placed, request product records, and request a licensee-initiated recall.

As of July 3, 2023, all five administrative holds have been lifted, according to the LCB.

Going forward, the regulator says it will conduct quarterly testing to ensure product safety.

Although banned in the 1970s, DDT and its by-product DDE can still be found in tiny quantities in agricultural soil across the US. These residual chemicals can then be absorbed and concentrated by cannabis crops, which are known hyper-accumulators of contaminants.


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