Legal cannabis is safe for consumers and environmentally sustainable

By Sydney Pahle, Research Assistant

Americans are becoming increasingly aware of the importance of buying organic foods in order to avoid personal and environmental harm. Yet when it comes to sourcing cannabis, some will turn a blind eye. Nobody knows what synthetic fertilizers and pesticides are used in black market cannabis. Cannabis grown responsibly and under California law is tested for pesticides to protect both consumers and the environment. The environmental harm that comes from supporting this illegal market should be openly explored, especially when legal alternatives are now a viable option.

The federal prohibition of cannabis, via the Marijuana Tax Act of 1937 and the Controlled Substances Act of 1970, did little to stop American use of the plant. Instead, it provided the perfect conditions for a wildly irresponsible and unregulated market. It is true that legal cannabis cultivation is now booming in several individual states after recent medical and recreational legalization of the plant. However, the federal designation of cannabis as a Schedule I drug means that the American black market still exists, and countless illegal grows still remain in operation. Illegal growers design their operations with secrecy in mind at all times. Hence, they spend little energy prioritizing environmental preservation and consumer safety.

Excessive amounts of synthetic chemical pesticides and fertilizers are frequently found on abandoned and trespassed grow sites on public and private lands. The substances utilized work quickly to combat diseases and deter predators, enhance bud growth, and increase THC levels. An illegal cultivation site with 7,000 plants and 5 acres will commonly contain 20 pounds of rat poison, 30 bags of fertilizer, as well as various hormones, insecticides, herbicides, and fungicides. (Mallery 28) 

The operations are large scale monocultures, which means they can be easily wiped out by a single disease if proper precautions are not taken. Cannabis plants are susceptible to mites, aphids, gnats, mold, mildew, as well as rats and deer. (Johnson 157) To combat this, laborers hand spray the plants with pesticides, and are exposed to high levels of toxicants for long periods of time while doing so. (Mallery 30) Officers who encounter these pesticides on grow sites are often not trained with proper removal, and either risk exposing themselves to toxicants if they attempt to remove them. (Klose 4) Absence of product screening in the black market means that consumers are unknowingly ingesting harmful substances. Chemical residue, mold, and mildew can be present on the cannabis buds when they are consumed, which can be fatal if used regularly. (Johnson 157) The various pesticides used haven’t been studied for reactions during combustion and inhalation, and no one is sure what the human health consequences of this will be. (Johnson 13) There are effective organic pesticides available, but they generally aren’t used in the black market.

Most pesticides concentrate themselves into the tissues of our flora and fauna through a process called bioaccumulation. In local food webs, they concentrate within each predator, and end up poisoning populations of critical species. 

Many of the pesticides used are banned in the USA, the EU and Canada, or have been approved only for ornamental plants, such as rose bushes. (Bauer 9) DDT is commonly used to combat mites, is a carcinogen that affects the nervous system, reproductive system and the liver. It has been illegal since 1973 in the USA, after Rachel Carson’s 1963 expose Silent Spring brought the pesticide’s health hazards to the public’s attention. (Mallery 29)

Pesticides move through our watersheds during rain, wind, sun, erosion and all other weathering events. They runoff into our streams, evaporate into our air, precipitate down in our rain, and soak into our soil and water table. This means, of course, that the pesticides end up in our water supply without us knowing. The use of illegal pesticides creates gaps in statewide water quality data, because the presence of the correct pesticides aren’t being tested for. (Gianotti 130) Further, the toxicants burn with our wildfires, degrading air quality and releasing dangerous substances to the will of the wind. (Klose 4) 

Similarly, excess fertilizer runs off into local waters, and through a process called eutrophication, robs streams, rivers, lakes and oceans of the oxygen they need to support their ecosystems. 

California is a hotspot for plant and animal biodiversity, and the Los Padres National Forest alone holds 23 animals and 4 plants that are considered threatened or endangered. (Klose 4) Many populations are reducing to dangerous levels, and pesticide use in illegal cannabis farming is doing no favors for our wildlife. Prohibition has historically made field research on cannabis difficult, but hopefully that can be remedied soon. Further research and funding for proper environmental reclamation of grow sites and their consequences will be beneficial. 

Bauer, Scott. “Illegal Marijuana Grow Sites on National Forest System Lands of Southern California.” SERCAL, vol. 28, no. 4, 2018.

Gianotti, Anne G. Short, et al. “The Quasi-Legal Challenge: Assessing and Governing the Environmental Impacts of Cannabis Cultivation in the North Coastal Basin of California.” Land Use Policy, vol. 61, 2017, pp. 126–134., doi:10.1016/j.landusepol.2016.11.016.

Johnson, Nick. Grass Roots: a History of Cannabis in the American West. Oregon State University Press, 2017.

Klose, Kristie. “Illegal Marijuana Grow Sites on National Forest System Lands of Southern California.” SERCAL, vol. 28, no. 4, 2018.

Mallery, Mark. “Marijuana National Forest: Encroachment on California Public Lands for Cannabis Cultivation.” Berkeley Undergraduate Journal, 1 Jan. 2011,