One person who opened the envelope at the Canadian mission was directly exposed to the unknown substance, which was now being analysed by experts, Turkey's disaster management agency AFAD said.
The consulate has been shut down for one day over security concerns, a Canadian embassy official told AFP.
There was no immediate claim of responsibility but the incident came amid mounting concerns about the growing national security threat posed by jihadists returning from war-ravaged Syria and Iraq.
Canadian officials said the two men accused of carrying out the separate attacks had recently converted to Islam and wanted to join the extremist fight.
The AFAD said experts quickly intervened at the Canadian consulate after the discovery of the suspicious envelope.
"One person who opened the envelope was directly exposed to the substance and six others were indirectly exposed...," it said, without making clear whether they had become ill.
"The envelope was sent to the laboratory to be analysed and see what the powder was... And was subjected to the necessary treatment."
An AFP reporter said the experts had left the Canadian consulate and were on their way to the Belgium and German missions.
Turkey has a long and porous border with Syria stretching from the Mediterranean to Iraq which has made it the main transit point for foreign rebels seeking to fight the Syrian regime.
Belgium, Canada and Germany are part of the international coalition against the Islamic State (IS) militants who have seized large parts of Syria and Iraq.
IS fighters have close to Turkish soil, trying to take the mainly Kurdish town of Kobane just a few kilometres (miles) from the border with Syria.
You’ve reached your limit of {{free_limit}} free articles this month.
Subscribe now for unlimited access.
Already subscribed? Log in
Subscribe to read the full story →
Smart Quarterly
₹900
3 Months
₹300/Month
Smart Essential
₹2,700
1 Year
₹225/Month
Super Saver
₹3,900
2 Years
₹162/Month
Renews automatically, cancel anytime
Here’s what’s included in our digital subscription plans
Exclusive premium stories online
Over 30 premium stories daily, handpicked by our editors


Complimentary Access to The New York Times
News, Games, Cooking, Audio, Wirecutter & The Athletic
Business Standard Epaper
Digital replica of our daily newspaper — with options to read, save, and share


Curated Newsletters
Insights on markets, finance, politics, tech, and more delivered to your inbox
Market Analysis & Investment Insights
In-depth market analysis & insights with access to The Smart Investor


Archives
Repository of articles and publications dating back to 1997
Ad-free Reading
Uninterrupted reading experience with no advertisements


Seamless Access Across All Devices
Access Business Standard across devices — mobile, tablet, or PC, via web or app
