A survey of 1,722 cannabis growers found 44% used chemical fertilizers, with hydroponic growing as the key predictor
A survey of 1,722 small-scale cannabis growers in Australia, Denmark, and the UK found that 44% used chemical fertilizers, supplements, or insecticides, with hydroponic growing as the only significant predictor of chemical use, and labeling issues made it difficult to determine which products contained harmful chemicals.
Quick Facts
What This Study Found
Researchers surveyed 1,722 current and recent small-scale recreational cannabis growers across three countries about their growing practices.
Overall, 44% reported using any chemical fertilizers, supplements, or insecticides.
Logistic regression found that hydroponic growing was the only significant predictor of chemical use. Other factors like country, experience level, or scale did not independently predict chemical use.
A major concern was plant growth regulators (PGRs), which limit plant size and stimulate bud production. Many PGRs have been banned from food crops but are found unlisted in cannabis growing nutrients sold online and in hydroponic stores.
The researchers found that product labeling and uncertainty about constituents made it difficult for both growers and researchers to determine which products contained PGRs or other harmful chemicals.
Key Numbers
1,722 growers surveyed across 3 countries. 44% used chemical fertilizers, supplements, or insecticides. Hydroponic growing was the sole significant predictor of chemical use.
How They Did This
Web survey of 1,722 cannabis growers in Australia, Denmark, and the UK. Logistic regression to identify predictors of chemical use. Assessment of product labeling and constituent transparency.
Why This Research Matters
As legal cannabis markets grow, consumer safety depends on understanding what chemicals end up in the final product. This study reveals that even small-scale growers commonly use chemicals, and the products available to them are poorly labeled, creating a hidden health risk for consumers.
The Bigger Picture
Legal cannabis markets have begun requiring pesticide and contaminant testing, but unregulated home-growing and gray-market production continue without oversight. The PGR problem is particularly concerning because these chemicals can be present in products marketed specifically to cannabis growers without appearing on labels.
What This Study Doesn't Tell Us
Self-selected web survey sample may not represent all cannabis growers. Self-reported chemical use may underestimate actual use. Product constituent analysis was limited by poor labeling. Three-country sample may not generalize globally.
Questions This Raises
- ?What health effects do PGR residues have on cannabis consumers?
- ?Would mandatory labeling of cannabis growing products reduce harmful chemical use?
- ?How does chemical use differ between legal commercial operations and home growers?
Trust & Context
- Key Stat:
- 44% of growers used chemicals, with PGRs potentially hidden in unlabeled products
- Evidence Grade:
- Moderate. Large multi-country survey, but self-selected sample and self-reported data introduce potential bias.
- Study Age:
- Published in 2018. Cannabis cultivation regulation has evolved in legal markets, though concerns about chemical contaminants persist.
- Original Title:
- Growing practices and the use of potentially harmful chemical additives among a sample of small-scale cannabis growers in three countries.
- Published In:
- Drug and alcohol dependence, 192, 250-256 (2018)
- Authors:
- Lenton, Simon(4), Frank, Vibeke A, Barratt, Monica J(3), Potter, Gary R, Decorte, Tom
- Database ID:
- RTHC-01729
Evidence Hierarchy
A snapshot of a population at one point in time.
What do these levels mean? →Frequently Asked Questions
What are plant growth regulators and why are they concerning?
Plant growth regulators (PGRs) are chemicals that control plant growth patterns. In cannabis cultivation, they are used to produce denser buds. Many PGRs have been banned from food crops due to health concerns including potential carcinogenicity. They can be present in cannabis growing products without being listed on labels.
Does this only apply to illegal growers?
The study surveyed small-scale recreational growers, but the chemical products they use are the same ones available at hydroponic stores that serve both legal and illegal growers. Legal commercial operations are typically subject to testing requirements, but home growers and gray-market producers generally are not.
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Cite This Study
https://rethinkthc.com/research/RTHC-01729APA
Lenton, Simon; Frank, Vibeke A; Barratt, Monica J; Potter, Gary R; Decorte, Tom. (2018). Growing practices and the use of potentially harmful chemical additives among a sample of small-scale cannabis growers in three countries.. Drug and alcohol dependence, 192, 250-256. https://doi.org/10.1016/j.drugalcdep.2018.07.040
MLA
Lenton, Simon, et al. "Growing practices and the use of potentially harmful chemical additives among a sample of small-scale cannabis growers in three countries.." Drug and alcohol dependence, 2018. https://doi.org/10.1016/j.drugalcdep.2018.07.040
RethinkTHC
RethinkTHC Research Database. "Growing practices and the use of potentially harmful chemica..." RTHC-01729. Retrieved from https://rethinkthc.com/research/lenton-2018-growing-practices-and-the
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.