Mainers can drop off unwanted prescription drugs at their nearest police or sheriff’s office Saturday, but a federal rule change prevents researchers from collecting data to help improve prescription practices.

The semiannual Drug Take-Back Day, sponsored by Maine law enforcement and the U.S. Drug Enforcement Administration, aims to ensure environmentally safe disposal of expired and unused medicines and reduce the risk of the drugs being stolen or otherwise consumed by individuals to whom they were not prescribed.

Pills and patches – but not liquids or needles – can be dropped off at law enforcement agencies between 10 a.m. and 2 p.m. The service is free and anonymous, with no questions asked.

“People should definitely take stock of what they have for prescription drugs, see what is no longer used or outdated, and take advantage of this,” said Roy McKinney, director of the Maine Drug Enforcement Agency.

The event – the 10th in Maine since such programs began in 2010 via an act of Congress – is taking place under new federal DEA rules approved a year ago that have effectively prohibited researchers from gathering anonymous data on what drugs are being returned and in what quantities. Such data had been used to reduce the cost of MaineCare – the state’s Medicaid program – by imposing 15-day limits on the initial prescriptions of often-wasted drugs, many of which are opiates.

Until this year, researchers – many of them pharmacy students – have counted drugs returned to collection boxes at Maine pharmacies and via a now-defunct mail-back program while under close supervision by law enforcement. The revised federal rules say collected drugs “cannot be sorted or inventoried after they have been deposited into a collection receptacle or received by a collector through a mailback package” except in situations where law enforcement has control and custody throughout the process.

Despite objections from researchers and public officials, the DEA said the changes were necessary to reduce the risk of drugs being diverted. “Relying on its experience … the DEA finds that any potential benefits of allowing authorized collectors or unregistered persons to independently inventory or sort controlled substances … do not outweigh the risks of diversion,” the agency said in its official comments published with the rule changes in the Federal Register.

The rule change effectively blocks the data collection, said Rodney Larson, founding dean of the Husson University School of Pharmacy, who has been involved in the tabulating of returned drugs by the University of Maine Center on Aging. “The rules allow for counting and cataloging medications under certain conditions, but the likelihood of it actually happening is quite limited due to the difficulty of getting law enforcement cooperation,” he said.

Larson said law enforcement agencies were reluctant to work with pharmacists and pharmacy students in accordance to the rules. “They don’t necessarily want to take the extra time or responsibility for providing the close supervision required while the medications are being counted and cataloged,” he said.

The data collected would help researchers better advise doctors on appropriate prescribing of opioid pain medications, antibiotics and drugs used to treat chronic conditions like diabetes and hypertension, and require consistent treatment to work properly.

U.S. Sen. Susan Collins, who had expressed concern over the proposed rule change in 2013, voiced disappointment about the restrictions on data collection. “It is unfortunate … that the final rule did not include the flexibility for non-law enforcement entities to count or conduct inventories of the drugs that are collected – a practice that could lead to better prescribing practices, improved patient education, and lower health care costs,” she said in a written statement to the Press Herald.

The DEA also stopped funding the national drug take-back program – including the transport and disposal of collected drugs – at the end of last year, but the Maine Sheriffs Association stepped up to organize Maine’s April 2015 take-back day, McKinney said.

The DEA has since resumed the coordination and funding of the program, and will continue doing so for the foreseeable future, said special agent Matt Barden, a spokesman at DEA headquarters in Arlington, Virginia. Barden said the agency had discontinued its role under the assumption that hospitals and pharmacies would have by then set up permanent take-back sites as they are permitted to do under a 2010 federal law, but discovered that far fewer than expected had done so.

“There are a lot of regulations to digest, but I’m hoping it will take off in future,” Barden said. “People love the idea they can take their unwanted medication whenever they drive to the pharmacy, rather than twice a year.”

In anticipation of the end of federal funding, Gov. Paul Le- Page in 2012 created a task force to develop less expensive disposal solutions. Maine Environmental Protection Commissioner Patricia Aho, who stepped down this month, reinterpreted state disposal rules to allow collected waste to be treated as household rather than hazardous waste. That allowed it to be burned at municipal waste incinerators instead of being sent to a hazardous waste incinerator out of state. DEP hazardous waste specialists had expressed concern over the change, public records showed, but it has since been implemented, McKinney confirmed Friday.

Maine has led the nation in drug take-back efforts, turning in tens of thousands of pounds at each event, more per capita than any other state. April’s event was no exception, McKinney said, with more than 23,000 pounds collected.