More than 70 staff members of a San Diego-area hospital are calling for a halt of all surgeries at the facility due to unidentified black, brown, and gray specks on surgical trays, the San Diego Union-Tribune reported.

The objecting staff have signed a petition to spur hospital officials to pause procedures until the issue is resolved. But officials at the facility, the Kaiser Permanente Zion Medical Center, have rejected the call, according to the Union-Tribune. A spokesperson for the facility did not respond to voicemails from Ars.

"Providing safe, quality, and timely care to our patients is our top priority, and we will continue to schedule surgeries at Zion that can be safely performed," Kaiser told the Union-Tribune in a statement. "We have confirmed that all measures we are taking to clean, process and transport surgical equipment to our Zion Medical Center for use [are] safe and medically appropriate."

The statement acknowledged that there was an "isolated issue" with equipment used to wash surgical instruments before they are sterilized. The problem resulted in "minute residual particles" from the hot water tank being left on the equipment.

"We are currently cleaning and flushing the lines of this equipment to remove all residual particulates," Kaiser said. "In the meantime, surgical instruments used at Zion Medical Center are being safely cleaned and processed at our nearby San Diego Medical Center and an outside agency."

However, Elizabeth Haynes, a surgical technician at Zion, told the local outlet that particles keep turning up on trays that hold surgical equipment, though not the surgical equipment itself. Last Friday, Haynes said staff had to open 23 surgical trays before finding one without the contaminants. The problem continued on her overnight shifts on Monday and Tuesday. “We opened 18 trays last night in an attempt to perform one procedure," Haynes told the outlet Tuesday.

Haynes added that management had assured staff that the particles—whatever they are—are sterile. Surgical equipment goes through a two-step process before use: a wash and then a trip through an autoclave, a pressurized steam machine used for sterilization. But Haynes argued that simply being sterilized doesn't mean it's fit for surgery.

"The fact that a contaminant is "safe" (not a microbe) doesn’t mean that contaminant is implantable," she said.

The Union-Tribune noted that the hospital's troubles seemed to begin last month when the facility reported a problem with its hot water lines. At the time, the facility said it transferred some patients to a sister facility but performed surgeries on a case-by-case basis. The facility's woes are another example of how critical water systems are for safe care at hospitals. Earlier this year, researchers at a Boston hospital reported on water purification systems in hospital ice machines inadvertently stripping out chlorine, leading to the deaths of three patients.

Leapfrog, a national nonprofit watchdog of hospital quality and safety, recently gave the Zion Medical Center an "A" grade. According to its review, the hospital was above average at preventing sepsis after surgeries but below average at preventing blood and urinary tract infections.