AUGUSTA, Maine — Patients who use medical marijuana and their caregivers said Monday that new rules proposed for Maine’s medical marijuana program could make it too expensive to grow a plant many depend on to manage pain, nausea and other chronic conditions.

Some who spoke at a public hearing on the rules proposal also questioned whether the state Department of Health and Human Services has the authority to implement such changes without legislative approval.

Monday’s public hearing on the new rules proposal attracted more than 100 medical marijuana advocates who packed one hearing room while others who attended sat in two rooms set up for overflow crowds.

“The Maine Medical Marijuana patient program was designed for sick Maine patients, and most sick Maine patients are low-income patients,” said Chris Kenoyer of the Maine Patients Coalition, an advocacy group. “The ones who need the law the most have been literally priced right out of using the program.”

The Department of Health and Human Services is floating the new rules proposal following two laws passed by the Legislature last year that eliminated the need for medical marijuana patients to register with the state and allowed patients to use medical marijuana with a doctor’s written permission. One of the laws also bars law enforcement from seizing marijuana that patients possess legally, and lets members of the public petition the Department of Health and Human Services to add to the list of medical conditions that qualify a patient to use marijuana.

But the proposed rules also require that all marijuana be grown in enclosed, locked facilities surrounded by fences at least eight feet tall “that completely obscure the view” of the growing marijuana, the rule document reads. In addition, the security measures must include motion-activated lights as a theft prevention measure.

The growing area also must be located at least 25 feet from a property line.

Those security restrictions on growing marijuana are unrealistic conditions for growing any crop, said Kelly Irwin of Falmouth. A motion-activated light, for example, would disrupt normal growing cycles, she said.

“Deer and wildlife would be the only thing to activate the lights,” she said. “Exterior lighting is an unreasonable required expense.”

And such security restrictions, which are expensive to implement, might not provide any security at all, said Jacob McClure, a Washington resident.

“An eight-foot fence where I live is a sign that says, ‘Medical marijuana, free for the taking,’” he said. “Everybody’s security situation is going to be different based on their living situation. You really have to let people make their own decisions based on what is appropriate and what isn’t appropriate for security.”

Steve Ruhl, a Lincoln resident, said the 25-foot setback requirement could disqualify many medical marijuana patients who own property from cultivating the plant.

“I have neighbors whose yards are 50 feet wide. Twenty-five feet on both sides, there’s nowhere for them to go,” he said.

“These plants are not dangerous,” he added. “They’re not toxic. We should not be treating them any different from any other garden plant in the state of Maine.”

Maine law has allowed the use of medical marijuana since 1999. In 2009, voters approved an expansion of the law, allowing the state to set up a system of medical marijuana dispensaries. Legislators approved two packages of changes to the laws in 2011, prompting the rules proposal from DHHS.

The department is accepting comments on the proposal through Aug. 23. While the agency could change its proposal based on public comments, the rules don’t require legislative approval to take effect.

That drew some criticism during Monday’s hearing from two lawmakers. Rep. Heather Sirocki, R-Scarborough, and Rep. Mark Dion, D-Portland, both called for a group of stakeholders to develop a rules package to regulate the state’s medical marijuana program.

“Some of [the rule changes] feel substantive, feel as if they go to the core of what this statute tried to accomplish when it was originally passed,” Dion said. “I think it’s important that this community, by its mere showing today, have a legitimate voice that needs to be taken into account.”