In coordinated raids last September, multiple California agencies swooped on a network of illegal cannabis-growing warehouses in Oakland, with state cannabis regulators singling out a salmon-colored warehouse complex surrounded by a 7,000-volt security fence.
A state agent told a judge that the warehouse building — which houses two licensed cannabis factories — was “highly likely” used by illegal growers to ship their product to the legal market. Inside the rooms, inspectors found 43,000 plants growing under high-intensity lights. None of the plants had the tracking tags that are placed on legal plants.
But what was surprising was what was found in the men’s room.
Alongside jugs of Hot Shot insect fogger and familiar chemicals were Mylar bags labeled in Chinese. Inside each bag were cellophane packets of wood shavings soaked in unknown pesticides.
Similar packages were found earlier this year at illegal farms in Siskiyou County, where lab tests found a mix of dangerous pesticides and fungicides that, when burned, produced a cloud of smoke that killed insects and fungi. Unusual substances included isoprocarb, which is not permitted in the United States; propenophos, an organophosphate so harmful its use was phased out here in 2016; and fenpropathrin, an acutely toxic pesticide that is fatal if inhaled.
Additional tests would reveal that the plants in the warehouse were also contaminated with the same pesticides.
Illicit Chinese pesticides present a new challenge for California cannabis regulators as they struggle to keep harmful chemicals out of licensed products. Some poisons are so unfamiliar that only a few chemical analysis labs in the state would be able to test for them if California required it.
A Los Angeles Times investigation based on confidential government records, public files, online sales and social networks found that over the past three years, the use of Chinese pesticides in cannabis cultivation has spread across California.
Yet authorities have not issued warnings to alert workers on cannabis farms to the dangers of these chemicals, or mandated testing for these chemicals on cannabis products sold to the public.
But their presence prompted multiple warnings from law enforcement personnel, including the state Department of Pesticide Regulation, the California National Guard and the state Environmental Protection Agency.
Internal state warnings warn that exposure to the contaminants can cause short-term headaches, eye irritation, nosebleeds and sore throat. Hazardous substances statements and scientific literature indicate that low-dose exposure is most likely to cause harm, raising the risk of cancer, memory loss, psychosis, developmental problems in children and death.
“I think the scariest thing with this stuff is what’s going to happen next,” said Siskiyou County sheriff’s Detective Sergeant Corey Pershing, where in 2022 a county environmental health officer armed with Google Translate on his cellphone first read the labels on similar packages.
Environmental citations issued by the California State Water Resources Control Board show that fumigants labeled Chinese appear primarily on Asian-owned farms, which is consistent with agricultural practices.
Smoke fumigation is not a common practice in the United States, but in China it is frequently used in place of pressure sprayers to aerosolize chemical treatments.
Some of the products showing up on cannabis farms are pesticides registered in China and sold online by vendors in Asia. Others are unbranded, with only links to WeChat accounts with California phone numbers and nicknames that translate to “Whatever Brother,” “Spider 1” and “Spider 2.”
An online marketplace for Chinese immigrants in California also sold unbranded fumigants, as did a Chinese-language site dedicated to cannabis cultivation. Both turned out to be linked to San Joaquin County businessman Adam Yang, whose social media accounts included a video demonstration of burning pesticides inside a cannabis greenhouse and whose Pinterest site offered photos of door-to-door deliveries of pesticides banned in Los Angeles and text messages from customers offering nationwide shipping.
The ads also told buyers they could cut the buds, apply smoke to them and sell them for smoking. “Rest assured that it can be used normally during flowering,” the ads said.
Yang acknowledged that his sites promote pesticides, but said they were part of a “collaboration” with a partner he declined to identify. “My role was limited to platform management, and I was not involved in direct sales or support,” Yang said via email.
Pesticides labeled Chinese have now been found in both illegal and licensed farming operations in at least six California counties. The poisons were present at half of the 25 illegal farms in Siskiyou County raided by a state task force during a sting operation in July 2023, leaving three officers requiring medical treatment after exposure.
They were also present at five farms raided by Siskiyou County sheriff’s deputies in late April, accompanied by a county health official who wore protective gear and a respirator to safely package the pesticides. At one farm, the deputy removed a large box filled with dozens of Chinese-labeled pesticides from the food pantry, where it had been hidden next to a large sack of rice. More fumigants were in a hutch, and inside two greenhouses half-cut beer cans were stacked against the walls, their interiors blackened with burned pesticide residue.
A farmer at the farm – who gave her first name as Feng – said she did not think the fumigants were dangerous. She pointed to a surgical mask on her face, indicating she wore one for protection while burning them.
Reports from the California National Guard lab and the Humboldt County Ecology Company show that most of the packages initially found in Siskiyou County contained a mix of pesticides and fungicides. Those tests identified 21 dangerous chemicals. California only tests for six substances in legal weed products, which means the vast majority of dangerous pesticides won’t be found on the legal market.
The Integral Ecology Research Center report warns that “these sites are highly contaminated with a variety of chemicals and concentrations,” with each bag containing at least one chemical that could be lethal if inhaled, and urges law enforcement personnel to “exercise extreme caution during all operations.”
These chemicals included five pesticides that were never approved for use in the United States, including chlorthiophos and the nerve agents fenobucarb and isoprocarb.
Prophenofos was also common, with early symptoms of exposure including headache, nausea and dizziness, tremors, vomiting, confusion and unconsciousness. It can be fatal if inhaled.
Siskiyou County sheriff’s deputies write a violation notice at an unlicensed cannabis farm where illegal pesticides were used.
(Page St. John / Los Angeles Times)
Siskiyou County has mandated that cannabis enforcement officers undergo periodic testing for blood toxicity. “Nobody really tells us what they mean. What’s normal? What’s intoxication?” said Pershing, who said he and his staff often get nosebleeds after cannabis farm raids.
California pesticide regulators and the National Guard issued their own law enforcement advisories last year, then broadened them as the Chinese pesticides showed up in Trinity County in the north, Alameda and Contra Costa counties on the coast and San Diego and San Bernardino counties in the south. The state Department of Fish and Wildlife in March reminded agents to undergo blood toxicity checks.
“We’re concerned not only for the first responders but for the users as well,” said Chris Bassett, a sheriff’s detective in San Bernardino County, whose team found the Chinese pesticide on five farms last year, including two in Los Angeles County. “Hopefully someone will need to test this substance on legal weed,” Bassett said.
Of the 25 pesticides found in the Oakland raid, only six are on the state Department of Cannabis Control’s testing list for products sold in licensed stores. The agency has taken no steps to add the rest of the chemicals to the list, though police reports and state records show it has encountered pesticides in weed entering the market.
Last October, Siskiyou County police officers stopped a box truck rented by VBX Labs LLC, a Los Angeles-based cannabis distributor and vape manufacturer. Police reports show the truck contained 4,500 pounds of illegal cannabis trim — commonly used to make concentrated oil for vape products — stuffed into 204 black garbage bags.
Such illegal loads destined for licensed distributors have been intercepted before, but this time the Department of Cannabis Control sent samples of the confiscated weed to the state agricultural lab for testing. The ensuing order revoking VBX’s cannabis distribution license cited the discovery of a banned chemical — paclobutrazol — commonly used by growers to increase the size and density of flower buds.
State lab test results reviewed by the Times show that the weed in VBX’s box truck was also contaminated with 16 other pesticides, including pesticides unique to Chinese fumigants: isoprocarb, fenobucarb, fenpropathrin and propenophos. None of these are tested for in cannabis products by the state, although other regulations prohibit their use as unregistered pesticides.
The presence of pesticides labeled Chinese was also omitted from the Department of Cannabis Control’s order revoking the license at an Oakland warehouse raided in September. The agency cited the presence of two banned chemicals routinely tested for in licensed cannabis. It omitted lab findings, seen by the Times, that documented isoprocarb, clothianidin, propenophos and fenpropathrin.
Nor did Cannabis Control agents immediately destroy the Oakland weed farm when they discovered illegal chemicals being used there. Instead, agents quarantined 43,000 plants and 1 ton of dried weed, and told operators, who had already failed to report the fate of 88 previous crops, to let the contaminated plants stand until Cannabis Control decided what to do.
When a state agent returned a month later, he found some plants were gone, new ones had grown, and more Chinese pesticides were on site.
A month after that, more quarantined cannabis went missing, including harvested plants, according to a state report.
Regulators didn’t revoke the warehouse’s licenses until three months after the raid. There was no indication of where the contaminated weed — which posed a danger to anyone who consumed it — had gone.
