Maine collects more unused medication per resident than any other state, keeping tons of powerful drugs out of the reach of children and out of sewers, waterways and drinking water supplies.

However, state environmental rules prevent disposal of much of the medical waste in Maine. So the pills and syrups have been trucked out of state to be incinerated at a specially approved facility, something that can be 100 times more expensive and use up a significant chunk of the funding devoted to collecting the drugs.

Now a team of state officials is about to test a potentially simple and cheap alternative: Composting.

They’ll put a variety of unused drugs — prescription and over-the-counter — into standard bins, then monitor the chemical changes as the mixture composts, or cooks. If it works as hoped, the denatured waste might be used safely to cover landfills or for other purposes, and Maine and others states will have an inexpensive solution to a growing national problem.

“The implications of this study, if it works, are huge,” said Ann Pistell of the Maine Department of Environmental Protection.

The national search for a way to collect and dispose of unused medication will be one focus of a three-day conference that begins this afternoon in Portland.

The eighth annual International Symposium on Safe Medicine is expected to draw about 100 experts from around the country to discuss medication disposal and drug abuse.

“Better solutions are needed,” said Lenard Kaye, director of the University of Maine Center on Aging, an organizer and sponsor of the conference. “We’ve got to stop flushing them. We’ve got to stop discarding them into landfills.”

Everything from anti-depressants to pain relievers and synthetic hormones have been flushed routinely down toilets, both in homes and in long-term-care nursing facilities.

Traces of the drugs are measurable in streams and rivers around the country.

Unused prescription drugs sitting in medicine cabinets, especially opiate-based painkillers such as Vicodin and oxycodone, also are a major source of drugs abused by teens and adults. Maine has the nation’s highest rate of residents in publicly supported treatment for prescription painkiller addiction, according to federal data.

Concerns about the environmental and public health threats led to what are considered to be the nation’s most aggressive drug collection and disposal efforts.

Maine residents can now take unwanted drugs to periodic collection events — one is planned for Oct. 29 at sites around the state — and to police stations and county sheriff’s offices equipped with secure drop boxes.

Local pharmacies also can provide special envelopes for customers who want to mail in their unwanted meds, although supplies of the mailers are short because funding has run out.

“I don’t think any other state in the country can claim as good a track record as ours in ensuring the average citizen has a way to safely dispose of unused drugs,” Kaye said. “We have the only approved model for mailback anywhere in the country, if not the world.”

Maine also collected more drugs per resident than any other state during national drug collections last October and April, according to Michael Wardrop, a Portland-based agent with the U.S. Drug Enforcement Agency who spoke to a group of southern Maine police chiefs last week. Nearly 20,000 pounds of drugs, in total, were collected in the two events, he said.

Wardrop also told the police officials that Maine’s environmental rules have complicated disposal efforts and required the DEA to take the medical waste to a Massachusetts trash incinerator.

The Massachusetts facility is not a licensed hazardous waste incinerator — there are none in New England — but it has a special waiver from that state to handle waste medication. It’s not clear how much the DEA is spending on disposal in Massachusetts, but some drugs collected in Maine in the past have been trucked to a hazardous waste incinerator in Arkansas at a cost of about $4 a pound, or $8,000 a ton.

Local trash incinerators charge about 4 cents a pound, or $88 a ton, for the waste they burn.

Some say Maine’s effective ban on in-state disposal is making it more difficult to collect the drugs and keep people from flushing them.

“It’s not making a lot of sense to a lot of people,” said Dr. Stevan Gressitt, a leader in the state’s efforts to collect and dispose of unused drugs. “They’re working at cross-purposes.”

Incinerators in Maine do accept controlled drugs such as painkillers, which are periodically thrown into the boilers by armed police officers. Those drugs have to be separated because of drug regulations and they are not considered hazardous waste because they are easy to destroy, officials said.

However, the majority of collected drugs are not sorted and contain toxic medications, including a long list of chemotherapy medications.

“When you aggregate all these pharmaceuticals (and put a large amount) into a solid-waste incinerator, then we don’t know what would be going out through the emissions,” said Carole Cifrino, environmental specialist at the Maine Department of Environmental Protection.

Cifrino said incinerators can qualify to burn such waste, but need to demonstrate that they burn waste at higher temperatures and for longer periods of time than other trash requires. “We would love for incinerators to (qualify), but it would take some money,” Cifrino said.

Maine incinerators don’t necessarily want to take in hazardous waste, either.

“We like our status as we are now,” said Anne Hewes, environmental manager with ecomaine, a municipally owned waste-to-energy incinerator about three miles from downtown Portland.

Other states are struggling with the same dilemma about medication disposal, Cifrino said. Some state officials and collection organizers are hopeful that composting could be an answer.

Scientists with the DEP and University of New England plan to start composting in five bins in Biddeford within the next few weeks. They’ll closely monitor the waste to see if toxic chemicals break down into more benign compounds.

Funding was provided by a federal grant through the Maine Department of Health and Human Services. That agency is concerned about the potential for drinking water contamination in long-term care facilities that have septic systems and well water.

Officials said they don’t know of any other study like it, and that successful results could have national, even worldwide, significance.

Kaye, at the Center on Aging, said he is confident there will be a solution. “The issue is a universal one,” he said.