Plant Growth Regulators (PGRs) are chemical compounds, both synthetic and naturally occurring, that are designed to modify or regulate plant development and growth. These substances mimic or interfere with the plant’s natural hormones, allowing cultivators to exert precise control over the growth cycle. In commercial agriculture, PGRs are used to achieve specific outcomes such as improving root development, increasing fruit set, or controlling plant height. The use of these compounds in cannabis cultivation, however, is a controversial practice that raises significant concerns regarding the final product’s quality and consumer safety. This article explores the motivations behind their use in cannabis and examines the potential risks they pose to individuals who consume the treated product.
How PGRs Affect Cannabis Cultivation
The primary motivation for using synthetic PGRs in cannabis cultivation is to increase commercial yield and change the physical characteristics of the flower. Growers apply these compounds to manipulate the plant’s hormonal pathways, which results in buds that are heavier and denser than those grown naturally. This manipulation allows for greater product weight from the same growing space, directly translating to higher profits for the producer.
Synthetic PGRs are often employed to shorten the flowering time of the cannabis plant, accelerating the harvest cycle. They achieve this by promoting cell division and elongation, leading to an artificially compact and heavy final product. This interference with the plant’s natural development, however, often comes at the expense of desirable qualities like potency and flavor.
The chemicals stimulate the plant to produce bulk rather than resinous glands (trichomes), which contain cannabinoids and terpenes. Consequently, PGR-treated cannabis tends to have a significantly reduced concentration of the compounds responsible for the plant’s characteristic effects and scent. Growers utilize these regulators to create a rock-hard flower that is heavy on the scale but chemically inferior to naturally cultivated cannabis.
Health Concerns Associated with Common PGRs
The health risks associated with PGRs in cannabis stem primarily from the synthetic nature of the most commonly used compounds, many of which are not approved for crops intended for human consumption. Three synthetic PGRs frequently identified in the illicit cannabis trade are Paclobutrazol, Daminozide, and Chlormequat Chloride. These compounds are typically approved only for ornamental plants, where they are not meant to be ingested or inhaled.
Paclobutrazol is a triazole fungicide that acts as a growth retardant by inhibiting the production of gibberellins, a class of plant hormones. When heated, as during smoking or vaping, Paclobutrazol can break down into harmful byproducts called nitrosamines, which are potent carcinogens found in tobacco smoke. Studies in animal models have indicated that exposure to Paclobutrazol can lead to liver damage and has been linked to reproductive system disorders.
Daminozide, also known by the trade name Alar, is another chemical that has been classified as a probable human carcinogen by regulatory bodies like the Environmental Protection Agency (EPA). Its use on food crops was voluntarily withdrawn in 1989 due to public concern over its potential to break down into unsymmetrical dimethylhydrazine (UDMH). UDMH is a degradation product that has been associated with carcinogenic activity in relevant animal models.
Chlormequat Chloride is used to restrict plant height, but it carries its own set of health warnings. Exposure to the chemical can cause irritation to the skin and eyes, and inhalation may lead to irritation of the nose, throat, and lungs. High levels of exposure have the potential to cause neurological symptoms, including tremors and seizures, and may result in liver damage.
Recognizing PGR-Treated Cannabis
Consumers can identify cannabis grown with synthetic PGRs by paying close attention to its visual and sensory characteristics. The most telling sign is the texture and density of the bud, which is unnaturally hard and compact, often described as “rock-hard.” This excessive firmness results from the chemicals forcing the plant to produce extra cell walls.
Another strong indicator is the appearance of the trichomes, which are the small, crystal-like glands that coat high-quality cannabis. PGR-treated flower often appears dull, with a noticeable lack of visible trichomes, resulting in a less sticky and resinous feel. The chemical manipulation also causes the pistils, the fine hairs on the bud, to appear excessively brown or reddish-orange, sometimes covering the entire surface of the flower.
The lack of natural development also impacts the smell and taste. While cannabis grown without PGRs is rich in terpenes, PGR-treated buds typically have a muted, hay-like, or chemical smell. When smoked, the taste is often harsh, bland, or bitter, sometimes accompanied by a heavy, lethargic feeling shortly after consumption. PGR buds may also feel unusually moist or spongy, a texture that can sometimes indicate a rushed or improper curing process.