U.S. energy companies rushing to exploit Pennsylvania's massive natural gas reserves have launched a public relations campaign to calm fears the bonanza is contaminating water with toxic chemicals.

Drillers are holding public meetings to assure people the chemicals used to help extract gas from Pennsylvania's majority share of the Marcellus Shale cannot escape into drinking-water wells.

Though scientists have yet to find definitive evidence that drilling chemicals have seeped into ground water, there are dozens of anecdotal reports from around the state that water supplies in gas-production areas have been tainted.

The public outcry threatens to impede exploitation of the 44-million-acre (18-million-hectare) Marcellus Shale, which geologists say might contain enough natural gas to meet U.S. demand for a decade.

People in gas-drilling areas say their well water has become discolored or foul-smelling; their pets and farm animals have died from drinking it; and their children have suffered from diarrhea and vomiting.

Bathing in well water can cause rashes and inflammation, and ponds bubble with methane that has escaped during drilling, they say.

That's the challenge facing Matt Pitzarella, a spokesman for Texas-based Range Resources Corp who recently told around 150 residents at the Hickory fire hall that new drilling techniques are much less damaging to the landscape than traditional ones, and that energy companies are subject to strict environmental regulations.

Other companies such as Chief Oil & Gas and Chesapeake Energy Corp have held community meetings.

Over a dinner of beef stew, baked beans and coleslaw hosted by Range, Pitzarella said the company encased its drilling shafts in layers of steel and concrete to ensure that chemicals used to help fracture the gas-bearing rock cannot escape into aquifers.

There are zero reports of chemical contamination of groundwater, he said.

Ron Gulla, who said his land has been polluted by Range's gas drilling, was incredulous.

I have never seen such a bunch of liars in my life, he shouted at Pitzarella, to scattered applause. You have put me through hell.

This is how the battle lines are being drawn in the U.S. struggle to reduce dependence on foreign oil and cut carbon emissions. Marcellus is the largest of the U.S. shale gas reserves, which are trapped in sedimentary beds making it more costly to extract. (For a map of shale reserve estimates, click: link.reuters.com/fur74c)

SULFUROUS SMELL

In rural Clearville, south-central Pennsylvania, Spectra Energy Corp is drilling to establish an underground gas storage facility.

Sandra McDaniel, 63, said federal authorities forced her, though eminent domain laws, to lease about five acres (2hectares) of her 154 acres to Spectra to build a drilling pad on a wooded hilltop.

McDaniel watched from the perimeter of the installation as three pipes spewed metallic gray water into plastic-lined pits, one of which was partially covered in a gray crust. As a sulfurous smell wafted from the rig, two tanker trucks marked residual waste drove from the site.

My land is gone, she said. The government took it away, and they have destroyed it.

Back in Hickory, Pitzarella acknowledged that water quality was the No. 1 concern but denied there was any escape of chemicals used in hydraulic fracturing, or fracking.

Drilling injects chemicals thousands of feet below the aquifers, and companies haul away waste water for treatment when the operation is finished, Pitzarella told the meeting.

Residents say escaped methane has caused some well water to become flammable, and its buildup has led to at least one explosion in a drinking water well. Many people in drilling areas drink only costly bottled water.

Pennsylvanians say they have not found fracking chemicals in their water only because they have not known what to test for, and because of the cost of testing.

Although the state's Department of Environmental Protection publishes a list of 54 chemicals that may be used in fracking, companies won't disclose what goes into the fluid, calling the information proprietary.

The composition of fracking fluid has been unregulated since the oil and gas industry won exemptions in 2005 from federal environmental laws including the Clean Water Act and the Safe Drinking Water Act.

According to the Endocrine Disruption Exchange, a Colorado research group that has investigated the health risks of fracking chemicals, about a third may cause cancer; half could damage the brain and nervous system, and almost 90 percent have the potential to harm skin, eyes and sensory organs.

Fracking chemicals include benzene, a carcinogen, plus toluene, methanol, and 2-butoxyethylene, a substance that can reduce human fertility and kill embryos, according to Damascus Citizens for Sustainability, a group that opposes drilling.

Range's Pitzarella said the chemicals make up only 0.05 percent of the fracking mixture, and that they include unspecified substances commonly used in households such as a friction reducer like that used in contact lenses and a biocide disinfectant used in swimming pools.

Stephanie Hallowich, 37, a mother of two, said she and her husband Chris moved to the outskirts of Hickory from suburban Pittsburgh 18 months ago for a quiet rural life but are now closely surrounded by four gas wells, a three-acre (1.2 hectare) reservoir containing water for drilling, a liquid extraction plant, and a gas compressor station.

Concerned about noise, air quality and her children's health, Hallowich would like to move but can't believe anyone would buy her house.

I don't want to find out in five years' time that my kids have cancer, she said.

Wayne Smith, 52, a Clearville farmer, said he made about $1 million in royalties over three years from gas taken from under his 105 acres, but he now wishes he never signed the lease and wonders whether tainted water is responsible for the recent deaths of four of his beef cattle, and his own elevated blood-iron level.

Smith would like to get his water tested for the full range of fracking chemicals but he can't do that without specifics on the fluid's composition. We don't know what's in it, he said. They won't tell us.

(Editing by Daniel Trotta and Eric Walsh)

Pennsylvania Energy