PORTLAND – Each day, about 150 to 175 of the more than 500 inmates at the Cumberland County Jail show up at its infirmary for evaluation and treatment of health problems that may range from broken arms and gunshot wounds to high-risk pregnancies.

Another 30 to 50 are treated in cellblocks for chronic medical conditions such as hepatitis C and cardiovascular disease.

The jail prides itself on being the first in Maine to win national accreditation, awarded in part because of the quality of around-the-clock medical care provided to sick inmates. That distinction is in jeopardy, however, as the jail’s cramped infirmary scrambles to deal with a surge of inmates with health problems.

“We have numbers that are just right off the charts regarding mental illness, substance abuse and basically an ill inmate population,” said Cumberland County Manager Peter Crichton.

Health care costs at Maine’s busiest jail have tripled in the past seven years to $2.8 million as demand for medical services exceeds the capacity to provide legally mandated services to inmates.

“People come to us from high-risk lifestyles, and the decisions associated with that lead to chronic disease. Some of that disease is substance abuse, some is mental illness, some is just a breakdown of the body in general from poor nutrition and lack of health,” said Cumberland County Sheriff Mark Dion. “This is the same population that looks to the emergency room at the hospitals for primary care.”

The infirmary’s crowded conditions are “almost becoming a safety issue,” said Diane North, an employee of Correctional Medical Services, the company that oversees medical care provided by the equivalent of 29 full-time nurses, doctors, counselors and medical technicians.

“My staff are becoming frustrated, and some do feel it’s unsafe and left exactly because of that,” North said.

County residents are scheduled to vote Nov. 6 on whether to approve $1.6 million for a 3,000-square-foot modular addition to provide more space for medical services.

It’s not clear how the project would be affected by Gov. John Baldacci’s proposal to consolidate the state prison system and Maine’s county jails, but Dion said the medical expansion can’t wait because the alternative would be to rely on hospital emergency rooms for care.

“I’ll be coming in with inmates in shackles. It’s safer, more secure and probably less costly in the long run to treat within the secure perimeter of the jail,” he said.