Thousands of protesters in 150 cities took to the streets to condemn the natural gas drilling process known as ‘fracking’ on Saturday, building on public concerns that the process could contaminate groundwater with potentially carcinogenic chemicals.

A protest against the process – which involves injecting chemicals, water and sand underground to break up rocks and free natural gas – was held in Ottawa on Thursday.

Protesters dressed in Hazmat gear marched on Parliament Hill and delivered a petition, signed by 10,000 Canadians, calling for a moratorium on fracking.

Scientists are divided on the risks associated with the process. The U.S. Environmental Protection Agency and many state regulators say the practice can be done safely. And the American Lung Association says the use of natural gas has helped decrease air pollution, as coal-fired power plants make the shift towards natural gas.

However the group that organized the demonstrations, Washington, D.C. based non-profit Food & Water Watch, claims that fracking “has already damaged communities and ruined lives. It pollutes water and makes people sick.”

Fracking is used to extract the immense volumes of natural gas which are found in formations of shale rock. Protesters against the practice are concerned that the wastewater from the process may leak into aquifers. They also cite studies which show poor air quality around gas wells.

Regulators argue that issues of air quality and water pollution are rare, but environmental groups and some scientists say more research is needed.

Canadian Green Party leader Elizabeth May told CTV News Channel other areas of the world are taking action against the “controversial” practice and she wants Canada to follow suit.

“It’s controversial everywhere including the recent discovery and confirmation by B.C. government authorities that fracking has caused an increase in earthquakes,” said May, referring to the B.C. Oil and Gas Commission report issued earlier this month, that concluded fracking was responsible for a series of small earthquakes between 2009 to 2011.

May also said that attempts to extract fuel in “unconventional” ways typically requires more energy input, thereby erasing any of the green benefits the fuel source initially offered.

“It takes a lot more energy and effort to get out unconventional anything than the stuff that was easy,” she said.

“The greenhouse gas emissions from unconventional natural gas completely erase any benefits of natural gas having been a relatively minor polluter compared to say, coal as a fossil fuel.”

The Green Party leader said Canada does not have the adequate regulations in place to monitor fracking and has not investigated the link between the practice and earthquakes.

May said she believes Canadians have good reason to become increasingly vocal in opposition to the practice.

“There are a lot of sensible reasons that Canadians are opposed to fracking,” she said.

Meanwhile fracking continues to be a contentious issue around the world.

Earlier in September, South Africa decided to permit fracking in the semi-desert region of Karoo, lifting a year-old moratorium. Officials cited a report by a technical team, as well as the economic benefits the natural gas extraction would bring to the impoverished region in their decision.

Vigorous debates over fracking are also taking place in France, Poland and other European countries.