First rinse the data was released a unique pilot project that aims to measure the consumption of Canadian marijuana through their wastewater, and the results are murky.
The Statistics Canada tested by plants & # 39; & # 39 in treatment, Halifax, Montreal, Toronto, Edmonton and Vancouver between March and August and analyzed the metabolites derived from THC, the main psychoactive compound in cannabis.
The purpose of & # 39; the study, used in Europe for many years, is to pursue the use of & # 39; pot before and after the recreational marijuana was legalized in & # 39; last October.
"This was done elsewhere in the world, but we are the first jurisdiction to do this on an ongoing basis for many cities," said Tony Peluso, assistant director with Statistics Canada.
Halifax above average
Preliminary results show that the rate of & # 39; per capita use of cannabis was & # 39; about 540 micrograms per person per week.
Of the five cities sampled, Halifax – With slight smaller site in the study – had a higher rate of & # 39; & # 39 average per capita consumption; 1.310 micrograms per person per week. However, the study also notes that the margin of & # 39; error for the city was quite large in & # 39; 707 micrograms per person.
The eastern coastal city was followed by Montreal at & # 39; 976 micrograms per person per week. Vancouver had the lowest average of the five cities in the sample, f & # 39; 288 micrograms per person per week.
Hard to measure
While this type of & # 39; study, known as epidemiology based wastewater, effective in & # 39; sense & # 39; expenditure and can & # 39; produces rapid responses, Statistics Canada said that the results may be affected by a number of & # 39; variables, including temperature, acidity and the presence of & # 39; industrial chemicals or bacteria wastewater.
In the online summary of the results, the agency said "disparity can & # 39; does not necessarily reflect a true difference in consumption, but can & # 39; is the result of & # 39; taking & # 39; samples or statistical methodology. "
"For example, the treatment plant wastewater in & # 39; Halifax was located in the central area of the city and as a result, consumption of cannabis measured there can not represent the entire metropolitan population of the city" .
Further taking & # 39; the following samples
In other cities, also sampled plants & # 39; suburban treatment where the use of cannabis can & # 39; be lower. As a result, Statistics Canada said the interurban comparisons are important as future changes.
"What we are most interested is if we Halifax consumption is increasing over time," said Peluso.
The sampling will continue & # 39; s going to April 2019. The survey wastewater will be used in conjunction with & # 39; Individual survey, but Peluso pointed out that people tend to report less use of their cannabis.
Statistics Canada also uses sampling of wastewater to try to monitor the use of & # 39; other drugs, including opiates, but Peluso said it is premature to determine whether they can be metered & # 39; accurate way.