DDT traces at 18 OK County sites
Eighteen cannabis producers in Okanogan County have been shut down by the Washington State Liquor and Cannabis Board (LCB) after random tests found soil contaminated with a remnant of the banned pesticide DDT.
Once it’s in the soil, DDT breaks down into related chemicals called DDE and DDD. These chemicals build up in plants and in fatty tissues of fish, birds and other animals, according to the Washington Department of Health. It becomes particularly concentrated in the cannabis plant, LCB said.
The farms are all south of Malott, on the west side of the Okanogan River, on former orchards, LCB said in an April 6 announcement. These are the first instances of DDT and DDE contamination found in cannabis in the state since it became legal in 2012. The contamination was present at more than twice the level that requires action, LCB Communications Director Brian Smith said.
The contamination was discovered when an LCB chemist reviewing random pesticide tests identified a pattern traced to a small geographic area. It affects 16 producers (growers) and two processors. Outside of the region near Malott, no DDE contamination above action levels has been detected in cannabis products across the state in hundreds of previous tests.
Tests of cannabis products from five licensees exceeded the allowable limit of DDE. This week, LCB collected products from the 13 other licensees and the state Department of Ecology collected soil samples for testing, LCB said. All businesses have been asked to initiate a recall of these products.
In addition, LCB officers purchased retail products connected with the licensees to test for contamination. This week, the first test results on six products came back positive for DDE above action levels.
The majority of the cannabis grown on the affected farms was sold wholesale to licensed processors, and most products were sold in retail stores as concentrates, Smith said. Only two of the growers sold cannabis directly to retailers, he said.
LCB emphasized to the licensees that the contamination doesn’t come from anything they’ve applied, but that the agency must take actions to protect public health and safety, Smith said.
All of the producers grow cannabis outdoors and the shutdown comes at the start of the growing season. Affected licensees either couldn’t be reached or declined to comment.
“The LCB recognizes the hardship and concern faced by affected licensees as well as the potential health and safety concerns of consumers. It is our hope to resolve this concern quickly, remain transparent with our licensees and stakeholders, and to take the appropriate actions to minimize impact overall,” LCB said this week.
LCB has been doing random testing of cannabis for pesticides since 2018. Test results over the past several years indicated the presence of DDE, but it was only recently that chemists and other experts identified a pattern that traced the contaminated samples to a small geographic area, Smith said.
LCB contracts with the Washington State Department of Agriculture (WSDA) to test for pesticides. The WSDA lab can detect 243 pesticides, including DDT and DDE.
Cannabis has a unique vulnerability to environmental contamination because the plants can absorb pesticides and heavy metals to a much higher degree than many other plants. When the plants are concentrated into oils, the contamination may be concentrated by a factor of five to 10, LCB said.
Because DDT and DDE bond tightly to soils and are not taken up by most plants, WSDA doesn’t specifically test orchard soils for these compounds, since they’re usually not available to the plant, WSDA Public Information Officer Amber Betts said.
It’s not clear if it’s possible to remediate the soil to eliminate the traces of DDT, Smith said.
Starting in 2022, cannabis-testing labs have been required to screen for 59 pesticides, but testing for DDT has been random because “contamination above actionable levels has not emerged elsewhere,” LCB said. As a result, licensees may not be aware that soil on their farms is contaminated unless their location was chosen for random testing, LCB said.
Stores have voluntarily pulled the products from their shelves and all affected licensees recalled their products. Recall notices are on the LCB website.
DDT was used widely as a pesticide in orchards from in the 1940s until it was banned in 1972. LCB believes the contamination is a remnant from that era.
People can be exposed to DDT by eating contaminated foods or breathing contaminated air or soil particles. DDT affects the nervous system and can cause seizures, and long-term exposure can affect the liver, according to the Department of Health. It is considered a probable human carcinogen. DDT was banned in 1972 because of the harm it caused to wildlife.
A 2003 Department of Ecology study of the lower Okanogan Basin (the headwaters are in British Columbia) found high levels of DDT in three species of fish from the Okanogan River. Studies by Ecology have also found high concentrations in fish in Lake Chelan and in other orchard regions.
Nationally, peak use of DDT occurred in 1959, when 80 million pounds (36 million kilograms (kg)) was applied. The U.S. Department of Agriculture began phasing out the pesticide because of concerns about its persistence in the environment and toxicity to nontarget organisms, according to Ecology.
DDT use in the lower Okanogan River basin probably followed national trends, although details are essentially nonexistent, Ecology said. A survey of pesticide use in British Columbia suggests that peak use in the Okanogan River basin occurred in the mid-1960s.