MONTPELIER, Vt. >> Worries about health effects, privacy and cost are fueling growing opposition to wireless, digital "smart meters" that utilities around the country are installing at homes and businesses and touting as key energy conservation and grid reliability tools.

Vermont appears poised to take an unusually aggressive stance. While several states have allowed utilities to charge a fee to customers who want to opt out of smart meters, Vermont’s governor is expected soon to sign legislation that would allow customers to say no without paying anything extra, at least until more studies are completed on the real costs of not deploying the meters.

"They’re the ones who came up with this," Sen. Robert Hartwell, D-Bennington and a leading supporter of the free opt-out, said in an interview. "The utilities didn’t really care what the ratepayers thought. So since they’re the ones who are trying to impose the new system, we think they’re the ones who should absorb the costs."

Dorothy Schnure, spokeswoman for Vermont’s Green Mountain Power Corp., said a smart grid will enable utilities to operate in a more efficient and environmentally friendly manner. She predicted most customers would be eager to see the change.

Under Vermont’s law, the costs of customers opting out — mainly having to send a meter reader to their home or business, will be spread across all customers, rather than being paid just by those who opt out.

Other states allow opt-outs, including California, Maine, Nevada and Oregon. But Schnure and others who watch the industry closely said they were not aware of any where consumers can skip smart meters for free. California imposes a $75 fee up front plus $10 a month for opting out.

Maine Supreme Court justices on Thursday heard arguments on whether that state should allow a free opt-out. Justices questioned a lawyer for the state Public Utilities Commission on why the agency hadn’t done more to investigate the safety of smart meters before allowing them to be deployed.

Vermont joined the smart meter movement in 2008, when state officials and utility executives announced plans to deploy the devices. They said the system would allow power prices to vary at different times of the day in keeping with demand, with a resulting incentive for consumers to run power-hungry appliances like dishwashers and clothes dryers at night when demand is low.

Another benefit cited by supporters of the technology: Because the meters would allow two-way radio communication, the utility would be able to see immediately when even a single customer lost power. No one would return from vacation to find a warm freezer full of spoiled food.

Smart meters got a big boost in 2009, when the Obama administration devoted $3.5 billion of its $787 billion economic stimulus package to grants to help utilities install the new technology. Vermont utilities got $69 million of that money.

Now, consumers and some government officials across the country are starting to question the push for smart meters on multiple fronts.

One concern is over the long-term health effects of being exposed to the radio-frequency radiation emitted by the meters. The International Agency for Research on Cancer, a branch of the World Health Organization, last year called radio-frequency radiation, which is emitted by cell phones, smart meters and many other devices, as a "possible carcinogen."

Smart meter supporters say the levels of RFRs emitted by the devices are much lower than those emitted by cell phones, and that governmental agencies have built big safety margins into emissions limits for both.

The Federal Communications Commission has rated smart meters as safe because they are considered very unlikely to cause bodily tissue heating or electric shock. But Dr. Poki Stewart Namkung, the public health officer for Santa Cruz County in California, issued a report in January calling the FCC standards "irrelevant."

"It says nothing about the safety from the risk of many chronic diseases that the public is most concerned about, such as cancer, miscarriage, birth defects, semen quality, autoimmune diseases, etc.," Namkung wrote.

Growing numbers of customers have raised their own concerns. Sudi Scull testified at a California Public Utilities Commission hearing in February that she developed painful headaches and ringing in her ears after Pacific Gas & Electric installed a smart meter on her house in San Francisco’s Bernal Heights neighborhood. The utility ultimately restored her analog meter, but she said the pain returned when smart meters were installed on her neighbors’ homes.

Consumers should not have to pay to opt out of having a smart meter installed, she said. "Let PG&E executives and shareholders incur the costs of an opt-out program."

PG&E spokesman Greg Snapper said the charges are necessary so that the utility can cover the cost of sending meter readers out to the relatively small number of homes spread over the company’s territory that have kept traditional meters. As of May 8, more than 90 percent of the company’s electricity meters had been upgraded to smart meters, and more than 27,000 customers, or less than 1 percent, had declined an upgrade, he said.

A second concern is over the privacy and security of the data collected by smart meters. The devices can tell when a utility customer is using equipment in the home ranging from power tools to a hot tub.

"It’s like a wiretap," said Justine Cook of Dorset, who has been active in a Vermont group opposed to smart meters. "It opens up a whole world of information that could be sold or hacked or used in ways we just don’t know."

Allen Gilbert, executive director of the Vermont chapter of the American Civil Liberties Union, said he wants to see assurances that police have to get a search warrant before accessing a utility customer’s usage data.

The U.S. Department of Energy’s inspector general, Gregory Friedman, said in a report issued in January that many companies deploying smart meters had not done enough to protect the systems from hackers who might be after customers’ personal information or who might be looking to sabotage utility grids.

"Without a formal risk assessment and associated mitigation strategy, threats and weaknesses may go unidentified" and expose utility grids "to an unacceptable level of risk," Friedman wrote.

And cost reductions promised when consumers adjust their usage to low-demand times of day have been slow to materialize, industry watchers said. Just the opposite has occurred in Santa Cruz County, officials there said.

The county Board of Supervisors imposed a moratorium on more smart meter development in January after getting Namkung’s critical health report. Among the reasons aside from health concerns listed by the board: the meters "have provided incorrect readings, costing ratepayers untold thousands of dollars."