Addictions, Drug & Alcohol Institute

High-THC Concentration Cannabis

With a legal market of cannabis products has come the wide distribution of manufactured products containing much higher levels of THC than what has been historically found in the plant.

Science to date shows a dose-response relationship between THC concentration and health consequences. Manufactured cannabis products may add further risks due to additives, residues and contaminants.

Researchers and policy makers are working to better understand these risks. This page contains recent reports and summaries that describe what we know so far.


High THC Policy | Final Report: Exploring Policy Solutions to Address Public Health Challenges of High THC Products (2022)

High THC Policy | Final Report. Exploring policy solutions to address public health challenges of high THC products. Final report to the WA Legislature from WA HCA and the ADAI Cannabis Education & Research Program

To address the emerging public safety challenge of increasingly available high-THC products (e.g. dabs, wax, concentrates), the WA State Health Care Authority was directed by ESSB 5092 (2021) to contract with the University of Washington’s Addictions, Drug & Alcohol Institute (ADAI) to identify areas of common ground and consensus, and develop recommendations for state policies related to cannabis concentration and mitigating detrimental health impacts.

The final report to the legislature, published in December 2022, describes recommendations for state policies based on the perspectives of WA stakeholders, research evidence on public policies designed to mitigate harms associated with non-medical use of high THC cannabis products and other legally commercialized health-compromising products, and cannabis policies that have been considered or adopted in North America.

Related resources:

Report citation:

Washington State Health Care Authority (HCA) & University of Washington Addictions, Drug & Alcohol Institute (ADAI). Washington State HCA report to the legislature. High THC policy | Final report: Exploring policy solutions to address public health challenges of high THC products. Engrossed Substitute Senate Bill 5092; Section 215(55); Chapter 334; Laws of 2021. Olympia, WA; Washington State Health Care Authority, December 2022.

Cannabis Concentration and Health Risks: A Report for the Washington State Prevention Research Subcommittee (2020)

logo from potency report

This consensus statement and report, published in November 2020, was developed by a workgroup of research scientists from the University of Washington (UW) and Washington State University (WSU) with the intent of providing policy makers with a summary of the current evidence on topics of public health importance related to cannabis concentration.

Download the report and additional resources:

Workgroup members include:

  • Beatriz Carlini, PhD, MPH, UW, Addictions, Drug & Alcohol Institute (Chair)
  • Celestina Barbosa-Leiker, PhD, WSU, Health Sciences
  • Carrie Cuttler, PhD, WSU, Department of Psychology
  • Julia Dilley, PhD, MES, Multnomah County Health Department and State of Oregon Public Health Division
  • Caislin Firth, PhD, MPH, UW, Addictions, Drug & Alcohol Institute
  • Kevin Haggerty, PhD, MSW, UW, School of Social Work
  • Jason Kilmer, PhD, UW, Department of Psychiatry & Behavioral Sciences
  • Mike McDonell, PhD, MS, WSU, College of Medicine, Behavioral Health Innovations
  • Nephi Stella, PhD, UW, Departments of Pharmacology and Psychiatry & Behavioral Sciences
  • Denise Walker, PhD, UW, Innovative Programs Research Group
  • Dale Willits, PhD, WSU, Criminal Justice & Criminology
  • Liz Wilhelm, Prevention WINS

Additional Resources

Other groups have also worked to describe what we know so far about high-potency cannabis and the implications for public health and policy decisions. Links to these reports and summary statements can be found below.