How Cannabis and Alcohol Show Up in Connecticut Crash Data
Linked crash and toxicology records from Connecticut show that testing positive for alcohol, cannabis, or both significantly increased the odds of driver injury.
Quick Facts
What This Study Found
Drivers who tested positive for alcohol alone, cannabis alone, or a combination of substances had significantly higher odds of injury in motor vehicle crashes. Lack of safety equipment was the single strongest predictor, increasing severe injury odds nearly 20-fold.
Key Numbers
Alcohol alone, cannabis alone, and combinations all significantly predicted driver injury. Lack of safety equipment increased severe injury odds nearly 20 times. Driver errors appeared as protective factors, which the researchers attributed to masking by other variables.
How They Did This
Researchers linked toxicology records (urine, blood, serum, vitreous) with crash data from Connecticut for 2017-2023. They used logistic regression and correlation analysis to identify predictors of driver injury and overall crash severity.
Why This Research Matters
Most impaired driving research relies on either crash data or toxicology data separately. Linking these datasets provides a more detailed picture of how specific substances relate to injury outcomes.
The Bigger Picture
As cannabis legalization expands, understanding its role in traffic safety requires better data integration. This study demonstrates that linking crash records with toxicology results can improve the analysis of impaired driving.
What This Study Doesn't Tell Us
The study covers a single state (Connecticut) and relies on toxicology data that may not reflect impairment at the time of the crash. The counterintuitive finding about driver errors suggests the model may have confounding issues.
Questions This Raises
- ?How do THC blood levels at the time of crash compare to post-crash toxicology results?
- ?Would similar patterns appear in states with different cannabis laws?
Trust & Context
- Key Stat:
- Lack of safety equipment increased severe injury odds nearly 20x
- Evidence Grade:
- Moderate: retrospective analysis linking two administrative datasets with large sample but limited ability to determine impairment timing
- Study Age:
- Published in 2025 using 2017-2023 Connecticut data
- Original Title:
- Integrating crash and fluids toxicology data to examine injury outcomes and associated driver behaviors.
- Published In:
- Accident; analysis and prevention, 221, 108200 (2025)
- Authors:
- Auguste, Marisa E, Pawelzik, Jennifer, Scholz, Caroline
- Database ID:
- RTHC-05974
Evidence Hierarchy
Looks back at existing records to find patterns.
What do these levels mean? →Frequently Asked Questions
Does this study prove cannabis causes crashes?
No. It shows that testing positive for cannabis was associated with higher injury odds in crashes, but toxicology results don't confirm impairment at the time of the crash.
What was the strongest predictor of severe injury?
Lack of safety equipment (seatbelts, etc.) increased the odds of severe injury nearly 20 times, making it the strongest predictor in the model.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-05974APA
Auguste, Marisa E; Pawelzik, Jennifer; Scholz, Caroline. (2025). Integrating crash and fluids toxicology data to examine injury outcomes and associated driver behaviors.. Accident; analysis and prevention, 221, 108200. https://doi.org/10.1016/j.aap.2025.108200
MLA
Auguste, Marisa E, et al. "Integrating crash and fluids toxicology data to examine injury outcomes and associated driver behaviors.." Accident; analysis and prevention, 2025. https://doi.org/10.1016/j.aap.2025.108200
RethinkTHC
RethinkTHC Research Database. "Integrating crash and fluids toxicology data to examine inju..." RTHC-05974. Retrieved from https://rethinkthc.com/research/auguste-2025-integrating-crash-and-fluids
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.