Committees that oversee research at big teaching hospitals and medical schools have deep ties to the health care and pharmaceutical industries but don’t clearly understand which relationships may pose conflicts of interests, according to a study from researchers at Massachusetts General Hospital.

The study, published Monday, shows that about one-third of the members of institutional review boards have some kind of ties to industry. This percentage is virtually unchanged from 2005, the last time Mass. General studied such conflicts.

Potential conflicts arise when a review board member who is paid by a certain company then votes on a project involving that company or a competitor. The concern is that bias could skew oversight of research projects that are meant to be objective.

While research institutions have taken steps to disclose and manage conflicts of interest, they still have a long way to go, said Eric G. Campbell, research director at the Mongan Institute for Health Policy at Mass. General, who authored the study.

“Our data suggests that members are not clear on what kinds of relationships form conflicts,” he said.

Another troubling finding, Campbell said, is that board members often fail to recuse themselves from discussions in which they have a conflict of interest. “That’s clearly something that needs to be addressed,” he said.

Campbell said his study showed signs of progress: The most “frowned upon” relationships, such as a drug company paying a scientist to do promotions, appear to be declining.

Many research institutions have detailed rules on conflicts of interest. At Beth Israel Deaconess Medical Center, for example, all review board members must disclose any potential conflicts during meetings and provide the hospital with an annual disclosure of all outside financial interests and positions held by them and their family members.

But even while beefing up these policies, research institutions in Boston and beyond have been ramping up efforts to partner with biotech and pharma companies. Many see these companies as key sources of research funding as federal funding wanes.

Dr. Terence R. Flotte, dean and provost of the University of Massachusetts Medical School in Worcester, said it’s important to avoid obvious conflicts. But he’s concerned that regulation could go too far and end up hampering important research and drug development.

“It is very helpful to have IRB members who have experience with industry relationships and can understand the good and the bad of these relationships,” Flotte said.

“We try to get to that balanced view. Industry ”” biotech and pharma ”” make very important contributions to developing therapies for diseases that don’t have adequate therapies right now.”

Priyanka Dayal McCluskey can be reached at priyanka.mccluskey@ globe.com. Follow her on Twitter @priyanka_dayal.