TORONTO -- The use of fentanyl, cannabis and methamphetamines spiked across cities in Canada during the early pandemic, according to a study, which analyzed wastewater in major cities.

Researchers behind Statistics Canada鈥檚 found this increase in drug consumption may be a strong contributing factor to the spike in overdose-related deaths last year.

showed opioid-related deaths were at their highest from April to September 2020.

To get this latest data, government researchers looked at wastewater in Halifax, Montreal, Toronto, Edmonton, and Vancouver; and then analyzed the chemicals in the water which are created when peoples鈥� bodies break down a drug.

Since 2019, the wastewater survey has been looking at samples from the cites鈥� various wastewater treatment plants. The latest study compared samples from March to July 2019 and from January to July 2020.

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Scientists saw that each city showed varying prevalence of the different types of drugs:

VANCOUVER

  • Per-capita loads of fentanyl in Vancouver were more than four times higher than in any other city.
  • Detectable fentanyl jumped 66 per cent between March and July 2020 compared to last year.
  • And compared to other cities, the highest levels of fentanyl were detected there, at 20 grams per million people per day.

EDMONTON

  • Methamphetamines were highest in Edmonton at 1,244 grams per million people per day, with approximately twice as much entering the sewers than in Vancouver.
  • Edmonton also saw detectable fentanyl surge by 108 per cent, with the city seeing the second highest amount of fentanyl after Vancouver.

TORONTO

  • The amount of fentanyl detected in Toronto鈥檚 wastewater supply tripled early in the COVID-19 pandemic.
  • The city saw a 207 per cent increase in detected fentanyl between March and July 2020 compared to last year.
  • Methamphetamines detected in the city鈥檚 sewers jumped 48 per cent, while cannabis jumped 27 per cent.

HALIFAX

  • Detectable cannabis was highest in Halifax at 742 grams per million people per day, followed by Vancouver. In contrast, Montreal and Toronto had the lowest levels.
  • This is consistent with Canada's 2019 National Cannabis Survey, which showed cannabis use in the third quarter of 2019 was highest in Nova Scotia (32.8 per cent) and lowest in Ontario (16.9 per cent) and in Quebec (11.5 per cent).
  • Compared to other cities, Halifax had the lowest levels of methamphetamines detected in the wastewater, at 21 grams per million people per day.

MONTREAL

  • The city had some of the lowest levels of detectable cannabis, with the amount in the wastewater increasing by 17 per cent compared to last year.
  • There was a 50 per cent decrease in fentanyl in the wastewater compared to the other cities, to 0.2 grams per million people per day.
  • Methamphetamines detected in Montreal also dropped by nearly 11 per cent to 189 grams per million people per day.

StatCan said the ongoing collection of wastewater samples will "contribute to a better understanding of the progression and the shifting landscape of drug consumption across Canada during and beyond the pandemic."

Researchers also urged local public health officials and law enforcement to use the data to target their harm reduction strategies.