A recent paper authored by researchers from the University of Wisconsin-Madison and institutions in Thailand has challenged the widespread belief that using water filtration—such as in a bong—significantly removes harmful compounds from marijuana smoke. According to the preprint, water does not appear to effectively filter out many chemical constituents of smoke when cannabis is combusted.
What Was Done
- Researchers compared the chemical composition of smoke from three popular cannabis strains—Bubble Gum, Silver Haze, and Hang Over OG—using two consumption methods: joints and bongs.
- They employed gas chromatography-mass spectrometry (GC-MS) to detect compounds in the smoke in the molecular weight range of approximately 5 to 350 g/mol.
Key Findings
- The smoke profiles from joints and water-filtered bongs were nearly identical for compounds within the detectable range. No compound in that range was found in joint smoke but absent in bong smoke.
- The study could not examine larger particles, aerosols, or metal ions—elements which might be filtered more effectively by water.
- Among the detected compounds, β-cis-Caryophyllene appeared consistently at high levels. The authors noted that this compound has under-studied but possibly significant physiological properties, including anti-inflammatory, antibiotic, antioxidant, anticarcinogenic, and local anesthetic effects.
Limitations and Caveats
- The paper is a preprint, meaning it has not yet undergone peer review.
- There are methodological constraints, especially related to measuring larger smoke particles and metal ions, and potential loss of smoke during sample collection. These limitations prevent definitive conclusions about filtration of those elements.
- The authors also withdrew the manuscript from bioRxiv because of a possibly conflicting bureaucratic issue concerning the location where some research was conducted.
Implications
The study suggests that water filtration via a bong may provide little protective benefit against many of the chemical compounds produced when cannabis is burned, at least within the detectable molecular weight range used in this study. It underscores the need for standardized methods in cannabis smoke research—so that different studies and contexts can be compared reliably.
For consumers who believe that using a bong is substantially safer than smoking a joint, this research indicates that those expectations may need to be reevaluated. As always, further research, especially peer-reviewed work able to account for larger particles and potential metal contaminants, is needed to form a more complete picture.
Dabbin-Dad Newsroom
