Do Mandatory Health Warning Labels on Consumer Products Increase Recall of the Health Risks of Cannabis?

Abstract

Introduction

Warning labels are an important source of health information. This study examined awareness of health warnings on cannabis packages over time in Canada—where large rotating messages are mandated—versus US states with legal adult-use cannabis, which have less comprehensive regulations.

Methods

Repeat cross-sectional data were collected from the International Cannabis Policy Study online surveys among past 12-month cannabis consumers in Canada and the US (n = 38,448). Free recall of warning messages was assessed in 2018–2020, followed by a prompted recognition task (2020 only). Adjusted logistic regression models tested differences in free recall and recognition of warnings between Canada and US states with and without legal adult-use cannabis (“legal” and “illegal” states, respectively).

Results

Free recall of ≥1 warning increased to a greater extent in Canada from 2018 (5%; pre-legalization) to 2019 (13%; post-legalization) compared to US “legal” (AOR = 1.93, p < 0.001) and “illegal” states (AOR = 1.80, p = 0.007), and from 2018 to 2020 (5% vs. 15%) compared to US “legal” states (AOR = 2.23, p = 0.027). In all jurisdictions, free recall of warnings was higher among more frequent consumers (p < 0.001) and those who purchased products from legal retail stores/websites (p < 0.001). With few exceptions, when a specific message was mandated (e.g., impaired driving), consumers were more likely to both freely recall and recognize that message (all p < 0.05).

Conclusions

Cannabis legalization is associated with greater recall of health warning messages. Awareness of specific warning messages was higher in jurisdictions where the associated warning was mandated on packages, suggesting that warning labels may improve knowledge of cannabis-related health risks.

Supplemental data for this article is available online at

Keywords:

• Cannabis
• health warnings
• free recall
• recognition

Acknowledgments

The authors would like to thank Robin Burkhalter, Vicki Rynard and Christian Boudreau for their help in creating the survey weights for the larger study, and to Maryam Iraniparast and Robin Burkhalter for analytic support.

Data availability

The datasets associated with this research are available from the corresponding author upon reasonable request.

Disclosure of interest

No potential conflict of interest was reported by the authors.

Notes

1 The following messages tested in the recognition task aligned with the Canadian mandatory health warnings introduced in 2018/2019: pregnancy or breastfeeding; driving or operating machinery; cannabis smoke/lung health; adolescents/young adults; mental health (e.g., anxiety or depression); addictive/habit-forming; memory and concentration; and delayed effects of edibles. The following messages aligned with warnings present in at least one US ‘legal’ state during the study period: driving/operating machinery; pregnancy/breastfeeding; addictive/habit-forming; cannabis smoke; delayed effects of edibles; mixing with alcohol/drugs; and cancer.

2 Note that while home growth is authorized in some jurisdictions, ‘grew my own’ was classified as ‘Illegal/Other/Unstated’ because it is not a possible source of exposure to mandated health warnings. Likewise, family member/friend was coded as ‘Illegal/Other/Unstated’ because no information was available on whether the family member/friend sourced their cannabis from a legal store/website and/or whether packaging was retained.

Additional information

Funding

Funding for this study was provided by a Canadian Institutes of Health Research (CIHR) Project Bridge Grant (PJT-153342) and a CIHR Project Grant. Additional support was provided by a Public Health Agency of Canada-CIHR Chair in Applied Public Health (DH). Funding was also provided by the Canadian Centre on Substance Use and Addiction through the Partnerships for Cannabis Policy Evaluation Team Grant administered by the Canadian Institutes of Health Research (SG, DH). The funders had no role in study design, collection, analysis or interpretation of the data, report writing or decision to submit the report for publication.