A cluster of nurses at Newton-Wellesley Hospital have reportedly been diagnosed with brain tumors, according to hospital officials who are assuring staff and patients that there’s “no environmental risk” at the facility.

But the Massachusetts Nurses Association says the hospital’s environmental testing was “not comprehensive,” as the union continues to investigate the situation.

The nurses diagnosed with brain tumors have worked in the maternal care labor/delivery unit on the hospital’s fifth floor.

As of earlier this week, 11 staff who worked at some point and for varying durations on the fifth floor had been interviewed by the Mass General Brigham Occupational Health Service.

Five cases were determined to be brain tumors of three different types — all of which were benign (non-cancerous). The only type of benign tumor that had more than one case was meningioma.

Six cases were determined to not be brain tumors, but rather other health concerns.

“Based on the results of the extensive and deliberate investigation… we want to reassure our dedicated team members and all of our patients that there is not an environmental risk at Newton-Wellesley Hospital,” Mass General Brigham wrote in its “Fifth Floor Work Environment FAQs” after a staff town hall about the situation.

“We take this very seriously; our top priority is providing high-quality care in a safe and healthy environment for our staff and patients,” Mass General Brigham added.

This situation at Newton-Wellesley Hospital was first reported by WBZ.

After hospital officials learned of the reported brain tumors, they conducted an investigation with the Department of Occupational Health and Safety, Newton-Wellesley Safety Officer, radiation and pharmaceutical safety offices, and external environmental consultants.

“Every staff member who came forward was given the opportunity to be interviewed by the Occupational Health and Safety team to evaluate each diagnosis in the context of their individual medical history and risk factors,” hospital officials said in a statement. “To evaluate for any possible environmental exposures in that area of the hospital, comprehensive environmental assessments following CDC guidelines began in December.

“The investigation found no environmental risks which could be linked to the development of a brain tumor,” the officials said, later adding, “Based on these results, we can confidently reassure our dedicated team members at Mass General Brigham/Newton-Wellesley Hospital and all our patients that there is no environmental risk at our facility. As always, the health and wellbeing of our staff, clinicians, and patients is our absolute top priority.”

Staff members have raised several concerns about this cluster of cases. The hospital addressed questions about whether brain tumor cases can be related to: wearing masks during the pandemic, the drinking water, use of x-rays, or the pharmacy on the floor below.

“There is no scientific evidence linking long-term mask use (including processing/re-wearing of masks) to the development of brain tumors,” reads the Fifth Floor Work Environment FAQs.

Water serving the hospital is tested regularly by the Massachusetts Water Resources Authority.

“Out of an abundance of caution, additional water samples from the tap and ice machines have been sent for additional testing by Triumvirate Environmental, an independent environmental testing firm,” reads the FAQs. “Those results should be available in the coming week.”

Hospital officials said they use appropriate x-ray safety techniques throughout the hospital.

“To make sure that there was not another, unknown, source of ionizing radiation on the Fifth Floor, radiation levels were surveyed across the Fifth Floor using Geiger counters,” the hospital wrote. “This did not find any abnormal/increased levels of ionizing radiation.”

The pharmacy located on the fourth floor processes chemotherapy medications.

“These are handled within an independently ventilated, closed system and with appropriate precautions and controls that have been validated as part of this investigation,” the hospital wrote. “The hoods used in the Fourth Floor pharmacy have been installed and tested to ensure that they are functioning properly and safely ventilating away from the building. This system was re-tested by Triumvirate Environmental, an independent environmental firm, as part of the investigation, and was found to be operating properly.”

The Massachusetts Nurses Association’s division of health and safety, consisting of occupational health nurses, is investigating the situation.

“We do not have a specific number (of nurses) we are releasing now because we are still verifying diagnoses via medical records. We do not have a specific cause as we are still investigating,” a spokesperson for the union said in a statement.

“We brought this to the hospital in December to urge an investigation by MGB,” the union spokesperson added. “We have been in communication with NWH nurses about this regularly and specifically with nurses who are self-reporting.”

The union spokesperson said the investigation is focused on the maternity unit, though they have reports from other areas as well.

“We are engaging with the hospital about their inquiry,” the union spokesperson said. “They only spoke to a small number of nurses and their environmental testing was not comprehensive. The hospital cannot make this issue go away by attempting to provide a predetermined conclusion.”

Originally Published: April 3, 2025 at 11:41 AM EDT