The Cambridge City Council voted unanimously Monday to oppose the construction of a Boston University BioSafety Level (BSL) 4 biodefense laboratory, a category of facility intended to house the most dangerous and least understood biological pathogens.

During lengthy public comment at the meeting, four area professors, a Boston city councillor, former gubenatorial candidate Grace C. Ross ’83, and a group of singing grandmothers voiced their objections to the facility, saying that the lab would endanger both its South End location and neighboring communities.

Although the Council vote cannot stop the construction, members said they were concerned that the effects of a pathogen leak would go beyond Boston city limits.

“If there is an accident, there is no recourse for us,” said Councillor E. Denise Simmons. “And if there is an accident in Boston, there goes Cambridge.”

According to the Centers for Disease Control and Prevention Web site, BSL-4 laboratories study “dangerous/exotic agents which pose high risk of life-threatening disease, aerosol-transmitted lab infections; or related agents with unknown risk of transmission.” In addition to the BU lab, six known BSL-4 laboratories currently exist in the United States, with another in the Rocky Mountains slated to open this year.

Intact samples of both smallpox and several varieties of viral hemorrhagic fever—including the Ebola virus—require a BSL-4 laboratory for study.

The Boston University facility is paid for in part by a one-time $120 million federal grant from the National Institute of Allergy and Infectious Diseases, a branch of the National Institutes of Health and the Department of Health and Human Services. The building will also house BSL-3 labs, which study pathogens with the potential for “serious health effects.” Many of these labs currently exist, including the Microbiology and Animal Resources Core Laboratory at the Harvard Medical School.

During the council meeting, David Ozonoff, professor and chairman emeritus of environmental health at the Boston University School of Public Health, said he felt compelled to appear before the council “out of a sense of conscience,” and that accidents at the BSL-4 facility could give way to “extremely high-consequence events.”

“I’ve spent my entire 40-plus year career in public medicine, and I don’t believe this facility serves a genuine public health purpose,” he said. “This lab may very well...make not just Cambridge less safe, but the world less safe.”

Elliot G. Mishler, professor of social psychology at the Harvard Medical School, echoed the concerns of other speakers, saying that “accidents occur at all levels of bioresearch labs, and even though the risk is low, it is acknowledged that...this risk is not zero.”

In addition to concerns about the facility itself, Boston City Councillor Charles H. “Chuck” Turner ’62 said at the meeting that he lacked confidence in BU’s safety procedures. Turner referred to a 2004 incident in which three BU researchers fell ill after unknowingly handling a contaminated strain of the bacteria tularemia.

However, according to the Boston Globe, BU officials did not report the illnesses to the Boston Public Health Commission until 28 days after DNA analyses revealed the strains under study had been contaminated. The Globe also revealed that BU failed to update its proposal for a BSL-4 lab, which claimed that BU labs had experienced no “laboratory-acquired infections” in more than 10 years, after the infections had been discovered.

“Boston University has not shown itself to be responsible in handling chemicals in its experimental work,” Turner said.

Officials from BU, the National Institute of Allergy and Infectious Diseases, and Mayor Thomas M. Menino’s office could not be reached for comment.

—Staff writer Nicholas K. Tabor can be reached at ntabor@fas.harvard.edu.