Several senior citizens in southern Canada required medical help after eating cannabis chocolate brownies served at a community lunch, Canadian media reported.

Ontario Provincial Police (OPP) launched an investigation into how the drug found its way into the chocolate treats given to elderly people in the tiny Ontario township of Whitestone.

Police said 10 people needed medical attention after eating the brownies, with some saying they felt dizzy and disoriented, and others experiencing nausea and vomiting.

OPP constable Miles Loach told CBC News that police officers would try to track down where the brownies came from.

“These luncheons are catered,” he said. “It’s still part of the investigation whether that was what happened … [that] somebody brought the wrong batch or somebody spiked them.”

Where cannabis is and isn't legal Show all 10 1 /10 Where cannabis is and isn't legal Where cannabis is and isn't legal UK Having been reclassified in 2009 from a Class C to a Class B drug, cannabis is now the most used illegal drug within the United Kingdom. The UK is also, however, the only country where Sativex – a prescribed drug that helps to combat muscle spasms in multiple sclerosis and contains some ingredients that are also found in cannabis - is licensed as a treatment Getty Where cannabis is and isn't legal North Korea Although many people believe the consumption of cannabis in North Korea to be legal, the official law regarding the drug has never been made entirely clear whilst under Kim Jong Un’s regime. However, it is said that the North Korean leader himself has openly said that he does not consider cannabis to be a drug and his regime doesn’t take any issue with the consumption or sale of the drug MARCEL VAN HOORN/AFP/Getty Images Where cannabis is and isn't legal Netherlands In the Netherlands smoking cannabis is legal, given that it is smoked within the designated ‘smoking areas’ and you don’t possess more than 5 grams for personal use. It is also legal to sell the substance, but only in specified coffee shops Getty Where cannabis is and isn't legal USA Although in some states of America cannabis has now been legalised, prior to the legalisation, police in the U.S. could make a marijuana-related arrest every 42 seconds, according to US News and World Report. The country also used to spend around $3.6 billion a year enforcing marijuana law, the American Civil Liberties Union notes AP Photo/Ted S. Warren Where cannabis is and isn't legal Spain Despite cannabis being officially illegal in Spain, the European hotspot has recently started to be branded, ‘the new Amsterdam’. This is because across Spain there are over 700 ‘Cannabis Clubs’ – these are considered legal venues to consume cannabis in because the consumption of the drug is in private, and not in public. These figures have risen dramatically in the last three years – in 2010 there were just 40 Cannabis Clubs in the whole of Spain. Recent figures also show that in Catalonia alone there are 165,000 registered members of cannabis clubs – this amounts to over 5 million euros (£4 million) in revenue each month Getty Where cannabis is and isn't legal Uruguay In December 2013, the House of Representatives and Senate passed a bill legalizing and regulating the production and sale of the drug. But the president has since postponed the legalization of cannabis until to 2015 and when it is made legal, it will be the authorities who will grow the cannabis that can be sold legally. Buyers must be 18 or older, residents of Uruguay, and must register with the authorities Getty Where cannabis is and isn't legal Pakistan Despite the fact that laws prohibiting the sale and misuse of cannabis exist and is considered a habit only entertained by lower-income groups, it is very rarely enforced. The occasional use of cannabis in community gatherings is broadly tolerated as a centuries old custom. The open use of cannabis by Sufis and Hindus as a means to induce euphoria has never been challenged by the state. Further, large tracts of cannabis grow unchecked in the wild Getty Where cannabis is and isn't legal Portugal In 2001, Portugal became the first country in the world to decriminalize the use of all drugs, and started treating drug users as sick people, instead of criminals. However, you can still be arrested or assigned mandatory rehab if you are caught several times in possession of drugs Getty Where cannabis is and isn't legal Puerto Rico Although the use of cannabis is currently illegal, it is said that Puerto Rico are in the process of decriminalising it RAUL ARBOLEDA/AFP/Getty Images Where cannabis is and isn't legal China Cannabis is grown in the wild and has been used to treat conditions such as gout and malaria. But, officially the substance is illegal to consume, possess and sell Getty

The incident happened at the community centre in Whitestone, a community of just over 900 people around 185 miles north of Toronto.

James McNurdo, a semi-retired man involved organising the monthly lunch club, said the brownies were served buffet-style.

“I’ve done these events for a number of years for this particular group so, obviously, I’m as mortified as anybody,” he told The Globe and Mail. “We’ve got to get to the bottom of this, no doubt about it.”

Mr McNurdo added: “The rumour mill is in overdrive.”

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Police had initial concerns some of the lunch club attendees might have been allergic to the substance – or could even have even driven home inadvertently stoned.

But Mr Loach said no-one had suffered any seriously adverse effects from the cannabis-laced cake. OPP officers got the names of everyone present at the lunch and made follow-up calls to make sure everyone was okay.