Pesticides Found in Cannabis During Recent Shelf Tests

By Jamie Toth and Jeff Rawson

Acequinocyl

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CAS #: 57960-19-7

SDS: link

EPA Pesticide Fact Sheet: link

Wikipedia: Not available

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Toxin and Toxin Target Database: Not Available

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Acequinocyl is a miticide used to control spider mites and is the active ingredient in Kanemite. The SDS and Laboratory Chemical Safety Summary display warnings that acequinocyl is an irritant, health hazard, and environmental hazard. It carries warnings that it may cause an allergic skin reaction, causes damage to organs (according to the Federal Register specifically the liver), and is very toxic to aquatic life (and poses a long-term hazard to them). These warnings are aimed at workers who apply acequinocyl because they are exposed to large amounts. The warnings on the SDS and LCSS are not directed towards consumers of produce treated by acequinocyl.

According to the final rule published in the Federal Register in 2021, which was based on an in-depth human impact study completed in 2020, the EPA states that “there is a reasonable certainty that no harm would result from aggregate exposure to acequinocyl and established tolerances for residues of that chemical…based on the risk assessments and information described above, EPA concludes there is reasonable certainty that no harm will result to the general population, or to infants and children, from aggregate exposure to acequinocyl residues.”

Bifenazate

CAS #: 149877-41-8

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Wikipedia: Not Available

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Bifenazate is a miticide that is the active ingredient in Actuate, Floramite, and Sirocco. According to the EPA New Pesticide Fact Sheet, bifenazate has “low acute toxicity by all routes of exposure (Category IV) with no evidence of dermal sensitization potential. It is non-irritating to skin and minimally irritating to eyes. Bifenazate is negative for mutagenic potential in a battery of required mutagenicity studies. Bifenazate has not yet received a human carcinogen classification since bifenazate is being considered as a non-food use pesticide and both the mouse and rat chronic toxicity/carcinogenicity studies are not required at this time.” Ecologically, bifenazate carries a high risk to aquatic life.

The fact sheet asserts that it has no dietary or residential uses, thus an aggregate risk assessment wasn’t performed. The primary human exposures considered in these sheets are occupational, involving workers in nurseries or greenhouses. Hazardous Substances Data Bank mentions that it could be a skin irritant.

Captan

CAS #: 133-06-2

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This fungicide carries warnings on its Laboratory Chemical Safety Summary for being corrosive, acutely toxic, as well as being a health and environmental hazard.

It is used on seeds or products such as fruits, vegetables, and ornamentals. It has been classified by the EPA as a ‘level B2 probable human carcinogen’ (a class that describes a possible carcinogen that is identified through animal incidences but has no evidence of human incidents). It received this classification for causing tumors in the duodena of mice exposed via the stomach or injection. Investigators believe the risk is from prolonged exposures to high doses, far higher than what would be experienced occupationally. Because the exposure would need to be so extreme, it’s not considered a likely human carcinogen. If ingested in large quantities, it could cause vomiting and diarrhea. Exposing the skin to Captan may cause dermatitis (or conjunctivitis).

Chlordane

This substance is banned in US Agriculture

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CAS ID#: 12789-03-6

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CDC, Toxic Substance Portal: link

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Chlordane was used as a pesticide in the United States from 1948 to 1988, often to fight termites. Its use was discontinued following concerns for the environment. Chlordane takes a long time to degrade in the environment, and has a half life of 30 years. This makes its high toxicity to aquatic life even more dangerous. Chlordane accumulates in the fat cells (lipids) of animals, and it has been linked to migraines, immunological issues, lymphoma, and several other cancers.

Chlorfenapyr

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CAS ID# 122453-73-0

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Developed from an isolate of a natural product of Streptomyces fumanus by American Cyanamid, chlorfenapyr is a pro-insecticide. It’s used in products such as Pylon, Piston TR, and Phantom insecticide. “Pro-insecticide” means that the compound deters insects only after activation by the metabolism of a host.

Initially the EPA denied a petition in 2000 for use of chlorfenapyr on cotton because of concerns around the toxicity, but it was ultimately approved in 2001 for use on non-food crops. This insecticide is now used in both homes (bedbugs and termites) and in greenhouses (caterpillars and gnats). The molecule can liberate cyanide when heated, and in 2016, 52 people were hospitalized and 33 people died in Pakistan when a baker mistakenly added the insecticide to their laddu, a baked confection.

Imidacloprid

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CAS #: 138261-41-3

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Imidacloprid is one of the ingredients of the pet pest control product Advantage. It’s also found as an ingredient in Bonide, Alias, Criterion, Mallet, Merit, and Pointer as well as many Fruit and Citrus insect control products.

It’s a neonicotinoid which is a class of insecticides that is modeled after nicotine (which has been used as an insecticide since the 1600’s). While in mammals the receptors for nicotine are located in both the central nervous system (CNS) and peripheral nervous system, in insects, only the CNS is impacted which makes nicotine (and neonicotinoids) extremely effective in their toxic impacts. This led to neonicotinoids beingused on a wide variety of food crops from corn to sugar beets. Following a 2018 review by the European Food Safety Authority (EFSA) which linked neonicotinoid pesticides to colony collapse disorder in some regions, the EU banned their use. In 2022, an EPA study found that imidacloprid could adversely effect 79 percent of species and 83 percent of critical habitats (the announcement notes that the definition of adverse effects does not mean that a pesticide is putting a species in jeopardy).

It would take an extremely high dose to impact human health, but imidacloprid is marked as ‘moderately’ toxic if ingested and is noted as having ‘low toxicity’ based on skin contact. According to the National Pesticide Information Center, “Imidacloprid is variable in toxicity if inhaled. The inhalation LC50 was estimated to be greater than 5323 mg/m3 for dust and 69 mg/m3 for aerosol exposure in rats.Imidacloprid dust is considered slightly toxic but the aerosol form is highly toxic.”

Malathion

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CAS #: 121-75-5

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Malathion is a classic insecticide. In low doses (0.5%), the FDA has approved its use as a treatment for head lice (despite the fact a study showed it had a 64% failure rate as a treatment in UK school children). It’s also used to kill mosquitoes and has been used in the United States since 1956 on a wide variety of crops, often sprayed from airplanes. Malathion works by preventing the nervous system of the insects from working properly, and it is also dangerous for bees. In 1981, to prove its safety before being sprayed across California in response to an outbreak of fruit flies, a director of California Conservation Corps swallowed a dilute solution of malathion.

It’s readily absorbed through the skin and the spray can also be accidentally inhaled, which will cause a variety of symptoms including nausea, muscle tremors and cramps, headache, and abdominal pain. In soil it has a half life of around 17 days, and half life in water is between 2 and 18 days.

Myclobutanil

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CAS #: 88671-89-0

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Because this fungicide is a developmental toxin, it is listed on the Prop 65 toxic substances list in California, yet California’s use accounts for around 50% percent of myclobutanil use in the US. It is not considered a carcinogen, so it’s still used on many crops like grapes, strawberries, and almonds.

Myclobutanil decomposes to toxic fumes (including hydrogen cyanide when heated), and thus has been banned for use in several US states and Canada for use on cannabis. It was found in shelf tests in both 2016 in Canada and 2019 in the US. Myclobutanil is the active ingredient in the fungicide Eagle 20.

Paclobutrazol

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CAS #: 76738-62-0

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Paclobutrazol (PBZ) both inhibits plant growth and can be used as a fungicide (it’s effective against powdery mildew). It is an antagonist of a plant growth hormone; its mechanism of action also increases seed growth and root growth. It has found many uses in agriculture because it can prevent the stems of cereal crops from bending, and helps crops become more resistant to frost. Overall, it reduces the growth of shrubs and trees while increasing the quantity and quality of fruits and vegetables, thus it is found in several commonly used PGR products such as Bonzi (Syngenta), Downsize (Greenleaf Chemical), Paczol (OHP), Piccolo and Piccolo 10XC (Fine Americas).

While there is a suspicion that paclobutrazol may have an impact on fertility and concerns that it is a carcinogen, there is no conclusive evidence.

Pymetrozine

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CAS #: 123312-89-0

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Wikipedia: Not Available

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Pymetrozine is a neuroactive insecticide found in Fulfill insecticide, Endeavor insecticide, Metroz, and Suruga. The World Health Organization (WHO) has concluded that pymetrozine poses a low toxicity risk to humans. Meanwhile, the EPA found that it was not mutagenic, but still posed a ‘likely’ cancer risk because rats and mice grew tumors after exposure. It also impacted pup development, but only at levels that were toxic to the parents.

Pyridaben

CAS #: 96489-71-3

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Wikipedia: Not Available

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This insecticide is used in orchards and vineyards to control mites, thrips, and aphids. Like many other chemicals on this list it is considered dangerous to aquatic life, but due to its properties it is not likely to leach into groundwater. According to the EPA, in the inhalation studies done on rats, no adverse effects were found even to the highest dosage tested. Generally it’s considered mildly toxic, and it has been classified as not likely to be carcinogenic in humans.

Tebuconazole

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CAS #: 107534-96-3

SDS: link

EPA Pesticide Archive Information: link

EPA Information regarding Environmental Risk: link

EPA Report on use on Hazelnuts in Oregon: link

Wikipedia: link

Pesticides Properties Database: link

Toxin and Toxin Target Database: Not Available

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Tebuconazole, a fungicide and plant growth regulator (PRG), is the active ingredient in Folicur, Orius, Elite 45 DF, and Tebustar. It has a long half-life and there is risk to birds who might feed on crops treated with tebuconazole. Additionally, it poses a chronic environmental risk to aquatic life. The FDA considers this fungicide to be safe for humans. However, the EPA has it listed as a possible carcinogen with moderate acute toxicity. The Pesticides Properties Database has it flagged as a possible endocrine disruptor.

Trifloxystrobin

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CAS #: 141517-21-7

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Wikipedia: Not available

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Effective against powdery mildew on apple trees, this fungicide is the active ingredient of Flint, Coronato, Stratego, and Compass. It is extremely toxic to several types of fish and aquatic invertebrates, but has a relatively short half-life in water due to microbial interactions (ranging from a few hours to 31.5 hours). It has a moderate half-life in soils, lasting between 1.9 to 16 days. The SDS carries warnings that it may cause skin irritation. It also may cause harm to breast-fed children or have other reproductive impacts in humans.ff The EPA Pesticide Fact Sheet states that, “EPA has concluded that there is a reasonable certainty that no harm will result to infants, children or adults from the use of trifloxystrobin on cucurbit vegetables, grapes, peanuts, pome fruits, turf, ornamentals, and imported bananas.“