Researchers propose that prenatal exposure to cannabis contaminated with the pesticide chlorpyrifos may compound developmental neurotoxicity through overlapping molecular pathways.
Cannabis regulators, toxicologists, public health officials, and pregnant individuals using cannabis.
Overlapping molecular pathways
What the researchers found
The proposed adverse outcome pathway shows that cannabinoids and chlorpyrifos share molecular targets affecting neurodevelopment. Both disrupt endocannabinoid signaling and acetylcholinesterase activity, potentially compounding effects on neuronal migration, synaptogenesis, and brain maturation when exposure occurs simultaneously.
Why it matters
Cannabis products can contain pesticide residues, and pregnant women may be unknowingly exposed to both. The emerging legal cannabis market still lacks consistent pesticide testing and standards in many jurisdictions.
The numbers in context
Several US states are moving toward pesticide regulation in cannabis, but standards vary widely. Chlorpyrifos was selected as a model pesticide due to its documented developmental neurotoxicity.
How the study worked
Theoretical construction of an adverse outcome pathway (AOP) by curating existing literature on the molecular, cellular, and tissue-level events linking prenatal cannabinoid-pesticide co-exposure to developmental neurotoxicity.
What this study cannot tell us
Entirely theoretical. The proposed adverse outcome pathway has not been experimentally validated as a whole. Real-world pesticide contamination levels on cannabis products are not well characterized.
How to read the evidence
Preliminary: theoretical framework without experimental validation.
When this study was published
Published in 2019.
The bigger picture
This paper highlights an overlooked risk: the conversation about cannabis and pregnancy typically focuses on THC alone, ignoring contaminants that may have their own or additive neurotoxic effects.
Questions still open
- What pesticide residue levels are actually found on commercial cannabis products? Would the combined exposure at realistic doses produce the predicted neurotoxic effects?
Common questions
Are there pesticides on cannabis products?
How could pesticides and cannabis both affect fetal development?
Read the original research
Adverse outcome pathway of developmental neurotoxicity resulting from prenatal exposures to cannabis contaminated with organophosphate pesticide residues.
Reproductive toxicology (Elmsford, N.Y.), 85, 12-18
Citation
Leung, Maxwell C K; Silva, Marilyn H; Palumbo, Amanda J; Lohstroh, Peter N; Koshlukova, Svetlana E; DuTeaux, Shelley B. (2019). Adverse outcome pathway of developmental neurotoxicity resulting from prenatal exposures to cannabis contaminated with organophosphate pesticide residues.. Reproductive toxicology (Elmsford, N.Y.), 85, 12-18. https://doi.org/10.1016/j.reprotox.2019.01.004
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