WSIPP: closer retail access linked to modest increases in cannabis use and some health and safety indicators

The Washington State Institute for Public Policy (WSIPP) presented long‑term research on Initiative 502 at the committee's Oct. 21 work session. Eva Westley, associate director for research, and Amani Rasheed, senior research associate and lead on the I‑502 evaluation, summarized multi‑year analyses of criminal justice outcomes, retail access and health and safety effects.

WSIPP confirmed prior findings that cannabis misdemeanor possession convictions among legal‑age adults dropped sharply after Initiative 502. Rasheed said monthly cannabis misdemeanor conviction rates for legal‑age adults "dropped to almost 0 immediately after initiative 5 0 2 goes into effect" and noted that underage conviction rates also declined but did not fall to zero (Amani Rasheed, 01:11:49).

Using a measure of average drive time to the nearest licensed retailer, WSIPP investigators reported that shorter drive times are associated with higher reported adult cannabis use. For example, a 50% reduction in average drive time corresponded to about a 6% higher likelihood of past‑month use and an 8.6% higher likelihood of heavy past‑month use, results Rasheed described as "modest in size but statistically significant" (Amani Rasheed, 01:19:08). WSIPP also analyzed Washington traffic fatalities and found that a 50% reduction in drive time predicted about 6% more drivers involved in fatal crashes annually (roughly 45 additional drivers statewide in a year), and among drivers who received blood tests an increased prevalence of THC positivity in areas with shorter drive times (Amani Rasheed, 01:19:08). The researchers emphasized that THC detection does not prove impairment or causation.

WSIPP examined adolescent outcomes using the Healthy Youth Survey and administrative school records. Rasheed reported that tenth‑ and twelfth‑grade students attending schools within a five‑minute drive of a retailer were more likely to report past‑month cannabis use, had on average 7% more monthly unexcused absences, and showed a 2.5% lower probability of graduating on time in four years; the graduation result was largely driven by rural schools in the sample (Amani Rasheed, 01:29:16).

Analyses of Washington Medicaid claims (2012–2023) found that after a retailer opened nearby, the probability of a Medicaid enrollee receiving a cannabis use disorder (CUD) diagnosis increased modestly. Rasheed reported a rise from about 1.6% to 1.8% predicted probability for underage enrollees (a roughly 13% relative increase) in tracts with retailers, and a 7% higher likelihood of CUD diagnosis for the adult Medicaid population post‑opening; CUD‑related hospitalizations increased by about 7% and inpatient/residential substance use treatment by about 24% in some analyses (Amani Rasheed, 01:34:49). The team used event‑study methods to test pre‑trends and said increases generally appeared after retailers opened, not before.

WSIPP emphasized limits and cautions: the Medicaid findings apply to the Medicaid population only and use diagnosis codes; THC‑positive test results do not establish impairment; and the analyses control for neighborhood characteristics but cannot determine causal biological effects or individual behavior pathways without further study. WSIPP said the work is part of a long‑term mandate (final benefit‑cost evaluation due 2032) and that follow‑up work will examine child welfare and workplace safety outcomes and economic effects of the legal market.

Ending: Committee members asked WSIPP to share reports and appendices; WSIPP said its next papers are planned on a roughly two‑year cycle and that all reports and executive summaries are available on its website. No committee action was taken at this meeting.