A decade into North America's fracking boom, the impact on wildlife and the environment remains largely unknown, according to a new study.

"We're conducting a giant experiment without even collecting the important data on the water, air, land or wildlife impacts," said Sara Souther, an ecologist at the University of Wisconsin, one of the co-authors of the peer-reviewed research examining the environmental impacts of shale gas development in the U.S. and Canada.

Although the technique of hydraulic fracturing shale has been used for at least 20 years, there is "surprisingly little research" on impacts, found the study, published in the journal Frontiers in Ecology and the Environment.

"We do know chemical contamination of ground and surface water is happening all the time but no one knows what the impacts are because the data isn't being collected," Souther said.

Spills, accidents, leaks from well casings and the dumping of toxic wastewater into streams are regular occurrences but no one knows the extent, she said. Often the data is not being compiled, while some U.S. states do not even ask the industry to report "minor" spills or accidents. In nearly all cases it is up to companies to "self-report."

The industry has long claimed there is no proof of water contamination. Souther accepted this until she learned that baseline studies had not been done before an area was fracked.

Water contamination tops a long list of environmental impacts including air and noise pollution and habitat fragmentation -- but in all cases there is little information, making it impossible to get a big picture of these multiple stressors on wildlife and the environment, she said.

"It's crazy. How can we know what the real risks are without any basic information?"

The fracking industry also enjoys an exemption from the U.S. Safe Drinking Water Act. That means the U.S. Environmental Protection Agency does not regulate the injection of chemicals into shale gas wells. Two-thirds of the 150 wells researchers investigated used at least one undisclosed chemical -- some used 20 or more.

Fracking sites operate with lots of noise, lights, flaring of gas and heavy vehicle traffic operating 24/7. The very few studies on wildlife impacts show that rare species like the sage grouse are being driven from their nest areas. Large parts of the Marcellus shale gas region is in the poor but heavily forested regions of Appalachia.

"These are the most biodiverse temperate forests in the world," said Souther.

Fracking has exploded in the U.S. since 2007. Hundreds of thousands of wells have now been fracked, which involves the deep underground injection of millions of litres of water and chemicals. Nine out 10 of the 11,000 to 12,000 new gas and oil wells drilled every year now use the technique.

Shale gas accounted for 39 per cent of all natural gas produced last year in the United States and about 15 per cent in Canada.

While gas wells are next door to schools and homes, and in the middle of farm fields, most are in remote areas.

"Forests or grasslands that were once continuous are now islands fragmented by a dense web of roads, pipelines and well pads. At what point does the canvas fall apart?" said co-author Viorel Popescu, an ecologist at Simon Fraser University.

The U.K. and any other country should conduct careful scientific studies on impacts with some pilot projects before plunging into full-scale shale gas development, she said.

"Bottom line: Shale gas has not been proven safe for freshwater or the environment."

This article was first published in The Guardian.

Stephen Leahy is the senior science and environment correspondent at Inter Press Service News Agency (IPS) based in Rome and Montevideo. To continue this work at a time of severe cutbacks and closure of many media, Leahy launched Community Supported Journalism.

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