Rates of cannabis use across all age groups have increased by 7.3% since legalization, with many users perceiving it as natural and therefore safe. However, the evidence used to assess cannabis safety and toxicity has an important limitation; most people consume cannabis by inhalation, while most of the research to date has involved injecting rodents to study cannabis’ effects.

Dr. Robert Laprairie and his research team changed that by developing a new approach to studying cannabis exposure via inhalation.

They purchased special smoke chambers designed to study the effects of cannabis smoke inhalation in pregnant rats. Using cannabis products found in local stores, Dr. Laprairie and his team found that cannabis smoke inhalation – while not benign – resulted in no large-scale changes in markers of maternal or fetal health.

This contrasts with previous assessments using injection models, where the effects were much more severe.

“We’re cognizant that our results could scare a mom away from the healthcare system. But what we’re trying to do is generate the evidence to help people understand the risks, using a model that more accurately assesses exposure.”

Dr. Robert Laprairie, Azrieli Future Leader in Canadian Brain Research

With his Future Leaders in Canadian Brain Research grant, The team is now tracking the long-term learning and development of the rat pups exposed to cannabis smoke in utero. So far they’re seeing deficits in memory, as well as deficits in attention scoring, in the pups exposed to high THC cannabis in utero.

What’s the impact?

Dr. Laprairie’s research shows that it’s both possible – and important – to test cannabis exposure in the format it’s typically consumed, via inhalation.

It also has important implications for public health.

Dr. Laprairie works with Health Canada’s Office of Controlled Drugs and Substances on several related projects and provides regular updates on his Brain Canada-funded work, which may inform upcoming policy documents.

Dr. Laprairie also collaborates closely with public health professionals in Manitoba and Saskatchewan. Together, they’ve created public education materials for pregnant people for distribution in cannabis stores and communicated key results on an ongoing basis to a network of clinicians and caregivers working with pediatric and maternal populations.

More on Dr. Robert Laprairie’s research