A picture is worth 1,000 words when it comes to cannabis.

A study of 870 Canadians between the ages of 16 and 30 at the University of Waterloo found that most participants reading edible labels still did not know whether the product contained a high or low level of THC.

“Using THC numbers to express potency of cannabis products has little or no meaning to most young Canadians,” said David Hammond of the university’s School of Public Health and Health Systems. “We’ve known for many years that people struggle to understand the numbers on the back of food packages and cigarette packages. Consumers seem to have equal or even more difficulty with THC numbers, which are used to indicate the potency of cannabis products.”

The study was split into two parts: The first tested whether subjects could tell how many servings were in a package and the second asked them to identify the product’s potency. Only six per cent could identify serving size on products without a label or a label that only displayed the weight. When the dosage was listed, 77 per cent could identify serving size.

Health Canada regulations currently require manufacturers to include product type, ingredients, potency, weight in kilograms and percentage of THC or CBD on labels, but this may not go far enough.

FILE: A warning label on one gram of cannabis is seen at Up’s cannabis factory in Lincoln, Ont.

The study found words and symbols proved far more effective in conveying information about product potency and appropriate serving sizes. Employing a “traffic light” system in testing allowed two-thirds of participants to identify products with strong potency versus a numerical system in which only one-third of people were able to do the same.

“Effective THC labeling and packaging could help reduce accidental over-consumption of cannabis edibles and adverse events, which have increased in jurisdictions that have legalized recreational cannabis,” Hammond said.

In light of the widespread uncertainty, Hammond said current regulations that put a cap on THC levels are a good idea, but more changes are needed.

“New regulations that limit cannabis edibles to a maximum of 10 mg per package are particularly important given that most consumers do not understand THC numbers,” he said. “However, the findings suggest that consumers will need easier-to-understand THC information for other products, including oils, concentrates and dried flower.”